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Background: Prior studies in breast cancer (BC) have demonstrated variability in the immune microenvironment of BCs across subtypes, with higher levels of immune infiltration observed in triple-negative (TN) BC. Clinical trials of immunotherapy in BC have largely targeted patients with TNBC, however many of these patients do not respond to treatment, suggesting heterogeneity across TN tumors. Further, immune infiltrated hormone receptor–positive, HER2-negative (HR+/HER2-) tumors have been observed. Patients with these tumors may benefit from immune checkpoint blockade (ICB). Identification of patients with immunogenic tumors would be valuable for future patient selection and stratification in clinical trials. In this study, we conducted comprehensive molecular profiling of a set of commercially procured BC samples to characterize the tumor microenvironment (TME) of HR+/HER2- and TN tumors and to identify patient or tumor features associated with immune infiltration. Methods: 163 surgically resected BC samples were used for this study (93 HR+/HER2-, 70 TN). Clinically validated immunohistochemistry (IHC) assays were used to evaluate the expression of two immune checkpoint (IC) molecules, PD-L1 (by VENTANA PD-L1 (SP142) Assay and Agilent PD-L1 IHC 28-8 pharmDx) and LAG3 (antibody clone 17B4). The presence of CD8+ cells was measured by IHC (Dako/Agilent clone C8/144B) and used to derive the spatial location and density (topology) of CD8+ cells within the TME. RNA sequencing (RNA-seq) was used to construct gene expression signatures representative of immune cell types. Furthermore, RNAseq data was used to identify expressed somatic mutations and to calculate the total expressed tumor mutational burden (‘eTMB’). Results: As previously reported, the prevalence of PD-L1 + tumors was higher in TN vs HR+/HER2− BC, however close to half (44.1% SP142 IC> 1%) of HR+/HER2- tumors showed some degree of PD-L1 expression. Similar patterns were observed for LAG3 IHC expression (32.3% and 64.7% of HR+ and TN tumors respectively with >1% expression). Concordant expression of the two markers (SP142 IC> 1% and LAG3 >=1% or < 1% and < 1%) was observed in approximately 80% of tumors in both subtypes. Less than 10% of tumors in both subtypes had high LAG3 (>1%) and low PD-L1(< 1%) expression. Most (82.4%) HR+/HER2- tumors in the dataset were deficient in CD8+ cells in both stroma and tumor parenchyma, however a subset (12.9%) were identified as having an ‘excluded’ CD8 pattern, and four (4.7%) were classified as ‘inflamed’. The frequency of both the excluded and inflamed states was slightly higher among the TN tumors (20.6% and 15.9% respectively). Expression of PD-L1+ occurred more frequently among tumors with higher CD8 expression. Among both TN and HR+ tumors, most ‘inflamed’ tumors were grade 3. We also examined a range of gene expression signatures representative of various immune cell subpopulations, their distribution within each subtype, and relationships with other molecular data. For example, expression of a CXCL13+ T cell signature, a cell type that has been shown to be predictive of response to anti-PD-L1 + chemo combo therapy in TNBC, was significantly higher in TN vs HR+ tumors, however, a large subset of HR+ tumors had levels of expression of the signature above the median observed in TN tumors. In addition, we noted that eTMB, while low overall, was positively correlated with certain immune-related expression signatures across HR+/HER2− samples, including signatures previously associated with improved response to ICB, as well as PD-L1 positivity. Conclusions: We observed heterogeneity in the immune profile of the real-world HR+ and TN tumors in this cohort. A subset of tumors in both subtypes expressed markers or signatures previously reported to be associated with response to ICB. (1) Cancer Cell. 2021 Dec 13;39(12):1578-1593.e8. Citation Format: Aparna Chhibber, Lloye M. Dillon, John B. Wojcik, Vishantie Dostal, George Lee, Fayaz Seifuddin, Scott Ely, Mark D. Stern, Charlie Benson-Garnett, Mustimbo Roberts, Jenny Wu. Characterization of Immune Contexture in HR+/HER2- and Triple Negative Breast Cancer in a Real-world Cohort [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-09-07.

Background: Cell-free DNA (cfDNA) is a noninvasive marker of cellular injury. Its significance in pulmonary arterial hypertension (PAH) is unknown. Methods: Plasma cfDNA was measured in 2 PAH cohorts (A, n=48; B, n=161) and controls (n=48). Data were collected for REVEAL 2.0 (Registry to Evaluate Early and Long-Term PAH Disease Management) scores and outcome determinations. Patients were divided into the following REVEAL risk groups: low (≤6), medium (7–8), and high (≥9). Total cfDNA concentrations were compared among controls and PAH risk groups by 1-way analysis of variance. Log-rank tests compared survival between cfDNA tertiles and REVEAL risk groups. Areas under the receiver operating characteristic curve were estimated from logistic regression models. A sample subset from cohort B (n=96) and controls (n=16) underwent bisulfite sequencing followed by a deconvolution algorithm to map cell-specific cfDNA methylation patterns, with concentrations compared using t tests. Results: In cohort A, median (interquartile range) age was 62 years (47–71), with 75% female, and median (interquartile range) REVEAL 2.0 was 6 (4–9). In cohort B, median (interquartile range) age was 59 years (49–71), with 69% female, and median (interquartile range) REVEAL 2.0 was 7 (6–9). In both cohorts, cfDNA concentrations differed among patients with PAH of varying REVEAL risk and controls (analysis of variance P ≤0.002) and were greater in the high-risk compared with the low-risk category ( P ≤0.002). In cohort B, death or lung transplant occurred in 14 of 54, 23 of 53, and 35 of 54 patients in the lowest, middle, and highest cfDNA tertiles, respectively. cfDNA levels stratified as tertiles (log-rank: P =0.0001) and REVEAL risk groups (log-rank: P P =0.02). Compared with controls, methylation analysis in patients with PAH revealed increased cfDNA originating from erythrocyte progenitors, neutrophils, monocytes, adipocytes, natural killer cells, vascular endothelium, and cardiac myocytes (Bonferroni adjusted P P ≤0.02). Conclusions: Circulating cfDNA is elevated in patients with PAH, correlates with disease severity, and predicts worse survival. Results from cfDNA methylation analyses in patients with PAH are consistent with prevailing paradigms of disease pathogenesis.

Clinical applications of precision oncology require accurate tests that can distinguish true cancer-specific mutations from errors introduced at each step of next-generation sequencing (NGS). To date, no bulk sequencing study has addressed the effects of cross-site reproducibility, nor the biological, technical and computational factors that influence variant identification. Here we report a systematic interrogation of somatic mutations in paired tumor–normal cell lines to identify factors affecting detection reproducibility and accuracy at six different centers. Using whole-genome sequencing (WGS) and whole-exome sequencing (WES), we evaluated the reproducibility of different sample types with varying input amount and tumor purity, and multiple library construction protocols, followed by processing with nine bioinformatics pipelines. We found that read coverage and callers affected both WGS and WES reproducibility, but WES performance was influenced by insert fragment size, genomic copy content and the global imbalance score (GIV; G > T/C > A). Finally, taking into account library preparation protocol, tumor content, read coverage and bioinformatics processes concomitantly, we recommend actionable practices to improve the reproducibility and accuracy of NGS experiments for cancer mutation detection.

Summary Activation of NOTCH signaling in human hematopoietic stem/progenitor cells (HSPCs) by treatment with an engineered Delta-like ligand (DELTA1ext-IgG [DXI]) has enabled ex vivo expansion of short-term HSPCs, but the effect on long-term repopulating hematopoietic stem cells (LTR-HSCs) remains uncertain. Here, we demonstrate that ex vivo culture of human adult HSPCs with DXI under low oxygen tension limits ER stress in LTR-HSCs and lineage-committed progenitors compared with normoxic cultures. A distinct HSC gene signature was upregulated in cells cultured with DXI in hypoxia and, after 21 days of culture, the frequency of LTR-HSCs increased 4.9-fold relative to uncultured cells and 4.2-fold compared with the normoxia + DXI group. NOTCH and hypoxia pathways intersected to maintain undifferentiated phenotypes in cultured HSPCs. Our work underscores the importance of mitigating ER stress perturbations to preserve functional LTR-HSCs in extended cultures and offers a clinically feasible platform for the expansion of human HSPCs., Graphical abstract, Highlights • Superior NOTCH-mediated expansion of human HSPCs in hypoxic cultures • Culture under hypoxia mitigates ER stress in human HSPCs • Hypoxia potentiates NOTCH intracellular signaling in cultured human HSPCs, Larochelle and colleagues concurrently activate NOTCH and hypoxic pathways in ex vivo cultures of human adult HSPCs to enable a clinically relevant expansion of cells with long-term repopulating potential after transplantation. They characterize the molecular intersection between the two signaling pathways and demonstrate the important role of low oxygen tension in mitigating ER stress during NOTCH-mediated expansion of human HSPCs.

Intermittent fasting blunts inflammation in asthma1 and rheumatoid arthritis2, suggesting that fasting may be exploited as an immune-modulatory intervention. However, mechanisms underpinning anti-inflammatory effects of fasting remain poorly characterized3, 4, 5. Here, we show that fasting in humans is sufficient to blunt CD4+ T helper cell responsiveness. RNA-seq and flow cytometric immunophenotyping of peripheral blood mononuclear cells (PBMCs) from volunteers subjected to overnight or 24-hour fasting, and 3-hours of refeeding implicate that fasting blunts CD4+ T helper cell activation and differentiation. Transcriptomic analysis reveal that the longer fast-duration has a more robust effect on CD4+ T cell biology. Through bioinformatic analyses, we identify the transcription factor FOXO4 and its canonical target FKBP5 as a potential fasting-responsive regulatory axis. Genetic gain- or loss-of-function of FOXO4 and FKBP5 is sufficient to modulate Th1 and Th17 cytokine production. Moreover, we find that fasting-induced or genetic overexpression of FOXO4 and FKBP5 is sufficient to downregulate mTORC1 signaling and suppress STAT1/3 activation. Our results identify FOXO4-FKBP5 as a novel fasting-induced, STAT-mediated, regulatory pathway to blunt human CD4+ T helper cell responsiveness., Summary: How fasting limits inflammation is poorly understood. RNA-seq analysis identified induction of the FOXO4-FKBP5 axis by fasting. Gain and loss of function studies in CD4+ T cells shows that FOXO4 and FKBP5 levels mediate T helper cell responsiveness, in part, by reducing mTORC1 and STAT1/3 signaling.

Lentiviral addition of βT87Q-globin, a modified β-globin with an anti-sickling mutation, is currently being used in gene therapy trials for sickle cell disease (SCD) and β-thalassemia patients. βT87Q-globin interferes with sickle hemoglobin (HbS) polymerization. Here, we generated the SCD mutation in an immortalized human erythroid cell line (HUDEP-2) to investigate the anti-sickling activity of βT87Q-globin. Sickle HUDEP-2 (sHUDEP-2) cells produced robust HbS after differentiation and sickled under deoxygenated conditions, comparable with SCD CD34+ progeny. Lentiviral transduction provided 9.5–26.8 pg/cell βT87Q-globin (R2 = 0.83) in a vector copy number (VCN)-dependent manner, resulting in a significant reduction of sickling ratios (R2 = 0.92). Interestingly, βT87Q-globin transduction markedly reduced endogenous βS-globin (R2 = 0.84) to an undetectable level (0.4–16.8 pg/cell) in sHUDEP-2 cells, as well as endogenous β-globin in human CD34+ cell-derived erythroid cells. RNA sequencing (RNA-seq) analysis with βT87Q-transduced sHUDEP-2 and human CD34+-derived cells revealed activation of inflammation- and proliferation-related programs, suggesting minimal changes in background gene expression except for βT87Q-globin expression and endogenous β/βS-globin suppression. In summary, using sHUDEP-2 and CD34+-derived cells, we demonstrated that lentiviral addition of βT87Q-globin strongly reduced endogenous β-/βS-globin expression, resulting in an anti-sickling effect. Our findings should be helpful to understand the anti-sickling effects of therapeutic genes in SCD gene therapy.

COVID-19 pathogenesis is associated with an exuberant inflammatory response. However, the tissue injury pattern and immune response in solid-organ transplant recipients (SOTRs) taking immunosuppressive therapy have not been well characterized. Here, we perform both cfDNA and cytokine profiling on plasma samples to map tissue damage, including allograft injury and delineate underlying immunopathology. We identified injuries from multiple-tissue types, including hematopoietic cells, vascular endothelium, hepatocyte, adipocyte, pancreas, kidney, heart, and lung in SOTRs with COVID-19 that correlates with disease severity. SOTRs with COVID-19 have higher plasma levels of cytokines such as IFN-λ1, IFN-γ, IL-15, IL-18 IL-1RA, IL-6, MCP-2, and TNF-α as compared to healthy controls, and the levels of GM-CSF, IL-15, IL-6, IL-8, and IL-10 were associated with disease severity in SOTRs. Strikingly, IFN-λ and IP-10 were markedly increased in SOTRs compared to immunocompetent patients with COVID-19. Correlation analyses showed a strong association between monocyte-derived cfDNA and inflammatory cytokines/chemokines in SOTRs with COVID-19. Moreover, compared to other respiratory viral infections, COVID-19 induced pronounced injury in hematopoitic, vascular endothelial and endocrine tissues. Allograft injury, measured as donor-derived cfDNA was elevated in SOTRs with COVID-19, including allografts distant from the primary site of infection. Allograft injury correlated with inflammatory cytokines and cfDNA from immune cells. Furthermore, longitudinal analysis identified a gradual decrease of cfDNA and inflammatory cytokine levels in patients with a favorable outcome. Our findings highlight distinct tissue injury and cytokine features in SOTRs with COVID-19 that correlate with disease severity.

Background: Cell-free DNA (cfDNA) is a non-invasive marker of tissue injury. Although being incrementally used as a clinical biomarker, its significance in pulmonary arterial hypertension (PAH) is unknown. Methods: Plasma cfDNA was isolated in two independent PAH cohorts (A, n=48; B, n=161) and healthy controls (n=48). Clinical variables and survival status were collected for Registry to Evaluate Early And Long-term PAH Disease Management (REVEAL 2.0) scores and outcome determinations. Total cfDNA levels were compared amongst controls and PAH patients and also used to predict transplant-free survival. A subset of samples from cohort B (n=96) and controls (n=16) were subjected to bisulfite sequencing and methylation analysis to quantify tissue-specific sources of cfDNA. Results: Median (IQR) cfDNA concentrations were higher in cohort A PAH patients (exploratory cohort) compared to controls and increased according to REVEAL 2.0 risk group: controls 13.7 (10.8-18.8) vs low risk 14.4 (10.0-19.9) vs medium risk 14.6 (11.3-28.2) vs high risk 31.5 (17.2-45.6) ng/ml (P Conclusions: cfDNA is elevated in PAH patients, correlates with disease severity and predicts worse survival. Methylation analysis of cfDNA in PAH patients is consistent with prevailing paradigms of disease pathogenesis. Thus, cfDNA may add prognostic power to PAH risk assessment and provide insight into disease progression.

Allostatic load (AL) refers to the cumulative "wear and tear" on an organism throughout its lifetime. One of the primary contributing factors to AL is prolonged exposure to stress or its primary catabolic agent cortisol. Chronic exposure to stress or cortisol is associated with numerous diseases, including cardiovascular disease, metabolic disorders, and psychiatric disorders. Therefore, a molecular marker capable of integrating a past history of cortisol exposure would be of great utility for assessing disease risk. To this end, we recruited 87 healthy males and females of European ancestry between 18 and 60 years old, extracted genomic DNA and RNA from leukocytes, and implemented a gene-centric DNA enrichment method coupled with bisulfite sequencing and RNA-Seq of total RNA for the determination of genome-wide methylation and gene transcription, respectively. Sequencing data were analyzed against awakening and bedtime cortisol data to identify differentially methylated regions (DMRs) and CpGs (DMCs) and differentially expressed genes (DEGs). Six candidate DMCs (punadjusted < 0.005) and nine DEGs (punadjusted < 0.0005) were used to construct a prediction model that could capture past 30+ days of both bedtime and awakening cortisol levels. Utilizing a cross-validation approach, we obtained a regression coefficient of R2 = 0.308 for predicting continuous awakening cortisol and an area under the curve (AUC) = 0.753 for dichotomous (high vs. low tertile) awakening cortisol, and R2 = 0.224 and AUC = 0.723 for continuous and dichotomous bedtime cortisol levels, respectively. To our knowledge, the current study represents the first attempt to identify genome-wide predictors of cortisol exposure that utilizes both methylation and transcription targets. The utility of our approach needs to be replicated in an independent cohort of samples for which similar cortisol metrics are available.

Analyzing host transcriptional changes in response to SARS-CoV-2 infection will help delineate biological processes underlying viral pathogenesis. Comparison of expression profiles of lung cell lines A549 (infected with either SARS-CoV-2 (with ACE2 expression)) or Influenza A virus (IAV)) and Calu3 (infected with SARS-CoV-2 or MERS-CoV) revealed upregulation of the antiviral interferon signaling in all three viral infections. However, perturbations in inflammatory, mitochondrial, and autophagy processes were specifically observed in SARS-CoV-2 infected cells. Validation of findings from cell line data revealed perturbations in autophagy and mitochondrial processes in the infected human nasopharyngeal samples. Specifically, downregulation of mTOR expression, mitochondrial ribosomal, mitochondrial complex I, and lysosome acidification genes were concurrently observed in both infected cell lines and human datasets. Furthermore, SARS-CoV-2 infection impedes autophagic flux by upregulating GSK3B in lung cell lines, or by downregulating autophagy genes, SNAP29 and lysosome acidification genes in human samples, contributing to increased viral replication. Therefore, drugs targeting lysosome acidification or autophagic flux could be tested as intervention strategies. Additionally, downregulation of MTFP1 (in cell lines) or SOCS6 (in human samples) results in hyperfused mitochondria and impede proper interferon response. Coexpression networks analysis identifies correlated clusters of genes annotated to inflammation and mitochondrial processes that are misregulated in SARS-CoV-2 infected cells. Finally, comparison of age stratified human gene expression data revealed impaired upregulation of chemokines, interferon stimulated and tripartite motif genes that are critical for antiviral signaling. Together, this analysis has revealed specific aspects of autophagic and mitochondrial function that are uniquely perturbed in SARS-CoV-2 infection.

Copy number variation (CNV) is a common type of mutation that often drives cancer progression. With advances in next-generation sequencing (NGS), CNVs can be detected in a detailed manner via newly developed computational tools but quality of such CNV calls has not been carefully evaluated. We analyzed CNV calls reported by 6 cutting-edge callers for 91 samples which were derived from the same cancer cell line, prepared and sequenced by varying the following factors: type of tissue sample (Fresh vs. Formalin Fixed Paraffin Embedded (FFPE)), library DNA amount, tumor purity, sequencing platform (Whole-Genome Sequencing (WGS) versus Whole-Exome Sequencing (WES)), and sequencing coverage. We found that callers greatly determined the pattern of CNV calls. Calling quality was drastically impaired by low purity (

Recent genetic studies have identified variants associated with bipolar disorder (BD), but it remains unclear how brain gene expression is altered in BD and how genetic risk for BD may contribute to these alterations. Here, we obtained transcriptomes from subgenual anterior cingulate cortex and amygdala samples from post-mortem brains of individuals with BD and neurotypical controls, including 511 total samples from 295 unique donors. We examined differential gene expression between cases and controls and the transcriptional effects of BD-associated genetic variants. We found two coexpressed modules that were associated with transcriptional changes in BD: one enriched for immune and inflammatory genes and the other with genes related to the postsynaptic membrane. Over 50% of BD genome-wide significant loci contained significant expression quantitative trait loci (QTL) (eQTL), and these data converged on several individual genes, including SCN2A and GRIN2A. Thus, these data implicate specific genes and pathways that may contribute to the pathology of BP.

A growing number of long noncoding RNAs (lncRNAs) have emerged as vital metabolic regulators. However, most human lncRNAs are nonconserved and highly tissue specific, vastly limiting our ability to identify human lncRNA metabolic regulators (hLMRs). In this study, we established a pipeline to identify putative hLMRs that are metabolically sensitive, disease relevant, and population applicable. We first progressively processed multilevel human transcriptome data to select liver lncRNAs that exhibit highly dynamic expression in the general population, show differential expression in a nonalcoholic fatty liver disease (NAFLD) population, and respond to dietary intervention in a small NAFLD cohort. We then experimentally demonstrated the responsiveness of selected hepatic lncRNAs to defined metabolic milieus in a liver-specific humanized mouse model. Furthermore, by extracting a concise list of protein-coding genes that are persistently correlated with lncRNAs in general and NAFLD populations, we predicted the specific function for each hLMR. Using gain- and loss-of-function approaches in humanized mice as well as ectopic expression in conventional mice, we validated the regulatory role of one nonconserved hLMR in cholesterol metabolism by coordinating with an RNA-binding protein, PTBP1, to modulate the transcription of cholesterol synthesis genes. Our work overcame the heterogeneity intrinsic to human data to enable the efficient identification and functional definition of disease-relevant human lncRNAs in metabolic homeostasis.

There is accumulating evidence that long noncoding RNAs (lncRNAs) play crucial roles in biological processes and diseases. In recent years, computational models have been widely used to predict potential lncRNA-disease relations. In this chapter, we systematically describe various computational algorithms and prediction tools that have been developed to elucidate the roles of lncRNAs in diseases, coding potential/functional characterization, or ascertaining their involvement in critical biological processes as well as provide a comprehensive summary of these applications.

There is accumulating evidence that long noncoding RNAs (lncRNAs) play crucial roles in biological processes and diseases. In recent years, computational models have been widely used to predict potential lncRNA-disease relations. In this chapter, we systematically describe various computational algorithms and prediction tools that have been developed to elucidate the roles of lncRNAs in diseases, coding potential/functional characterization, or ascertaining their involvement in critical biological processes as well as provide a comprehensive summary of these applications.

Visual Abstract, Highlights • LDGs are a subset of neutrophils that were elevated in psoriasis and associated with the severity of disease. • In psoriasis, LDGs associated with noncalcified coronary plaque burden beyond cardiovascular risk factors and in vitro, induced endothelial cell damage. • Compared to normal-density granulocyte neutrophils, platelet-associated biological pathways were upregulated in LDGs, suggesting enhanced platelet adherence to the LDG surface. • LDGs co-localized with platelets in circulation, and the LDG-platelet interaction associated more strongly with non-calcified coronary burden by coronary CTA compared to LDGs alone., Summary Psoriasis is an inflammatory skin disease associated with increased cardiovascular risk and serves as a reliable model to study inflammatory atherogenesis. Because neutrophils are implicated in atherosclerosis development, this study reports that the interaction among low-density granulocytes, a subset of neutrophils, and platelets is associated with a noncalcified coronary plaque burden assessed by coronary computed tomography angiography. Because early atherosclerotic noncalcified burden can lead to fatal myocardial infarction, the low-density granulocyte−platelet interaction may play a crucial target for clinical intervention.

Background and aims High density lipoprotein cholesterol (HDL-C) is associated with risk of cardiovascular disease (CVD); however, therapeutic manipulations of HDL-C have failed to reduce CVD events. This suggests that HDL-C and the atheroprotective capacity of HDL are not directly linked. The goal of this study was to evaluate the relationships between HDL-bound proteins and measures of atherosclerosis burden and HDL function. Methods The HDL proteome was analyzed using mass spectrometry in 126 human subjects, who had undergone coronary computed tomography angiography (CCTA) to quantify calcified (CB) and non-calcified (NCB) atherosclerosis burden. Partial least squares regression analysis was used to evaluate associations between HDL-bound proteins and CB, NCB, or cholesterol efflux capacity (CEC). Results Significant overlap was found among proteins associated with NCB and CEC. Proteins that were associated with NCB displayed an inverse relationship with CEC, supporting a link between this protective function of HDL and clinical plaque burden. CB was associated with a set of proteins mostly distinct from NCB and CEC. When CVD risk factors were evaluated, BMI had a stronger influence on important HDL proteins than gender, age, or HDL-C. Most HDL proteins associated with function or atherosclerosis burden were not significantly correlated with HDL-C. Conclusions These findings indicate that the HDL proteome contains information not captured by HDL- C and, therefore, has potential for future development as a biomarker for CVD risk. Additionally, the proteome effects detected in this study may provide HDL compositional goals for evaluating new and existing HDL-modification therapies.

Background: Acute pain, the most prominent complication of sickle cell disease (SCD), results from vasoocclusion triggered by sickling of deoxygenated red blood cells (RBCs). A key factor influencing HbS oxygenation is the intracellular concentration of 2,3- diphosphoglycerate (2,3-DPG). 2,3-DPG, an intermediate substrate in the glycolytic pathway, decreases oxygen binding and stabilizes the deoxygenated hemoglobin. Pyruvate kinase (gene PKLR, protein PKR) is a rate-limiting enzyme in glycolysis; variants in PKLR may affect PKR activity, 2,3-DPG levels in RBCs, subsequent frequency of sickling and acute pain episodes (APE). There is thus a strong biological basis for exploring PKLR as a candidate gene affecting acute pain in SCD. Methods: The study population for genetic association consists of 2 cohorts: 1) 242 adults with HbSS from King's College Hospital (KCH), London, UK, with complete hospitalisation records over 10 years (2004-2013 inclusive) as the "discovery" cohort; 2) 977 children with HbSS or HbSb 0 thalassemia from the Silent Infarct Transfusion (SIT) trial, with a 3-year history of severe vasoocclusive pain based on hospitalization, as the "validation" cohort. Both studies were approved by the local Institutional Review Boards at KCH and Vanderbilt University Medical Center, respectively. An independent cohort comprises 52 adults with SCD enrolled under 3 protocols - NCT00011648, NCT00081523, and NCT03685721 - approved by the NHLBI Review Board (NIH), for evaluation of imbalance in allele expression. Genome scan for the KCH cohort was performed using llumina's Infinium "MEGA" chip (1.7m markers). The SIT DNA samples were genotyped using Illumina HumanHap650Y array 5 (661K markers) or Illumina Infinium HumanOmni1-Quad array (1.1m markers). The results were quality controlled followed by genotype imputation based on the 1000 Genomes Project phase 3 data. An annualised "hospitalisation rate" as a measure of pain incidence rate, was calculated by dividing the number of hospital admissions for severe acute pain by the number of years of observation for KCH and SIT cohorts (Fig A). We performed association analysis with common SNPs at PKLR locus using data from our genome-wide SNP set and a linear mixed modelling approach incorporating a genetic relatedness matrix to take account of relatedness, plus sex and age as fixed covariates. We corrected for multiple testing after quantifying the linkage disequilibrium (LD) within PKLR and used this to calculate appropriate significance levels. For the PKLR region and hospitalisation rate, the modified significance level was p Results: 7 of 47 variants evaluated in PKLR were associated with hospitalization rate (LnLnHospRate) in the discovery cohort: intron 4 - rs071053, and intron 2 - rs8177970, rs116244351, rs114455416, rs12741350, rs3020781, and rs8177964). All 7 were validated in Fisher's meta-analyses of the KCH and the SIT cohorts using p Conclusion: Intronic variants of PKLR are associated with hospitalization rate for acute pain episodes in adults and children with SCD. We show that the intronic variants are likely to influence acute pain by affecting expression of the PKLR gene using allele-specific expression analyses, although the causal variant is unclear. These results support PKLR as a genetic modifier of SCD. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Chronic exposure to glucocorticoids (GCs) can lead to psychiatric complications through epigenetic mechanisms such as DNA methylation (DNAm). We sought to determine whether epigenetic changes in a peripheral tissue can serve as a surrogate for those in a relatively inaccessible tissue such as the brain. DNA extracted from the hippocampus and blood of mice treated with GCs or vehicle solution was assayed using a genome-wide DNAm platform (Methyl-Seq) to identify differentially methylated regions (DMRs) induced by GC treatment. We observed that ∼70% of the DMRs in both tissues lost methylation following GC treatment. Of the 3,095 DMRs that mapped to the same genes in both tissues, 1,853 DMRs underwent DNAm changes in the same direction. Interestingly, only 209 DMRs (

Background Sickle Cell Disease (SCD) is a genetic disorder caused by a single amino acid substitution in the ß-hemoglobin chain. Clinical manifestations of SCD are multisystemic and heterogeneous, with a wide range of organ damage between patients despite identical genetic mutations. The sub-phenotypes of SCD reflect damage to different organs arising from the pathophysiology of the disease. Biomarkers, such as N-terminal-pro-Brain natriuretic peptide (NT-proBNP), tricuspid regurgitant velocity (TRV), and hemolytic parameters provide readouts of the degree of different organ damage and are known risk markers. Dissecting its pathophysiology along known biological pathways has led to development of therapeutic targets, but we still do not fully understand the pathogenesis for much of the organ damage. Given the complexity of the pathophysiology of SCD that is likely to involve multiple overlapping and interacting biological pathways, an agnostic, network-based approach using gene expression data with annotated risk markers provides an attractive alternative. We assessed the plausibility of using such an approach with bilirubin levels as a phenotype. Bilirubin is a breakdown product of red blood cells (RBCs) that is measured in routine labs and a validated hemolytic and disease severity marker of SCD. Methods Using RNA-Seq data from 224 patients with SCD (80% HbSS and HbSBeta0 thalassemia combined, 15% HbSC, 5% HbSBeta+ thalassemia, and 0.4% HbSD), we performed a differential gene expression (DGE) analysis and weighted gene co-expression network analysis (WGCNA) of 12,450 genes. For the DGE analysis we used total bilirubin levels as a continuous variable for the main phenotype of interest, adjusting for age, sex, and hemoglobin genotype. We then conducted WGCNA to identify modules of genes with similar coexpression patterns, which we functionally annotated (via the ClusterProfiler R package) for interesting biological themes. Results Of the 12,450 genes, 10,604 were protein coding, and 1,560 were lncRNAs, and 286 were other non-coding transcripts. 3,509 (2,975 coding, 447 lncRNA, and 87 other non-coding) were considered differentially expressed (unadjusted p-value < 0.05) according to bilirubin level. Through the WCGNA, the genes clustered into 11 co-expression modules, representing a range of biological pathways. Four of these modules had representative eigengenes that were significantly correlated with bilirubin (p < 0.05), and we focused on 2 of these that had biologically interesting functions. The first module of interest (turquoise) consisted of 3,636 genes (3,371 protein-coding and 210 lncRNA) (25% differentially expressed, and 62% upregulated). Genes in this module have been associated with cellular functioning of younger RBCs, validating the presence of the significant Gene Ontology (GO) biological pathways listed in the bar graph (mitochondria gene expression, ribonucleotide processes, etc.), and aligning with expected processes as the young RBCs replace the degraded RBCs that had caused the high bilirubin. Notably, this module contained the biliverdin reductase A (BLVRA) gene (differentially expressed at p < 0.008), which reduces biliverdin to bilirubin. The other highlighted module (red) consisted of 914 genes (846 protein-coding and 57 lncRNA) (42% differentially expressed, and 97% upregulated). Multiple pathways in the red module were related to catabolic processes. As previously stated, bilirubin is the byproduct of hemoprotein catabolism, suggesting an interesting correlation. Additionally, this module contained 2 other pathways associated with porphyrin, which is a component of RBCs that contains the heme group and is involved in heme biosynthesis. Conclusion Taken together, these results provide interesting insights into the biological pathways driving one facet of sickle cell disease's many clinical manifestations. Figure 1 Disclosures No relevant conflicts of interest to declare.

Notch activation in human CD34+ hematopoietic stem/progenitor cells (HSPCs) by treatment with Delta1 ligand has enabled clinically relevant ex vivo expansion of short-term HSPCs. However, sustained engraftment of the expanded cells was not observed after transplantation, suggesting ineffective expansion of hematopoietic stem cells with long-term repopulating activity (LTR-HSCs). Recent studies have highlighted how increased proliferative demand in culture can trigger endoplasmic reticulum (ER) stress and impair HSC function. Here, we investigated whether ex vivo culture of HSPCs under hypoxia might limit cellular ER stress and thus offer a simple approach to preserve functional HSCs under high proliferative conditions, such as those promoted in culture with Delta1. Human adult mobilized CD34+ cells were cultured for 21 days under normoxia (21% O2) or hypoxia (2% O2) in vessels coated with optimized concentrations of Delta1. We observed enhanced progenitor cell activity within the CD34+ cell population treated with Delta1 in hypoxia, but the benefits provided by low-oxygen cultures were most notable in the primitive HSC compartment. At optimal coating densities of Delta1, the frequency of LTR-HSCs measured by limiting dilution analysis 16 weeks after transplantation into NSG mice was 4.9- and 4.2-fold higher in hypoxic cultures (1 in 1,586 CD34+ cells) compared with uncultured cells (1 in 7,706) and the normoxia group (1 in 5,090), respectively. Conversely, we observed no difference in expression of the homing CXCR4 receptor between cells cultured under normoxic and hypoxic conditions, indicating that hypoxia increased the absolute numbers of LTR-HSCs but not their homing potential after transplantation. To corroborate these findings molecularly, we performed transcriptomic analyses and found significant upregulation of a distinct HSC gene expression signature in cells cultured with Delta1 in hypoxia (Fig. A). Collectively, these data show that hypoxia supports a superior ex vivo expansion of human HSCs with LTR activity compared with normoxia at optimized densities of Delta1. To clarify how hypoxia improved Notch-mediated expansion of LTR-HSCs, we performed scRNA-seq of CD34+ cells treated with Delta1 under normoxic or hypoxic conditions. We identified 6 distinct clusters (clusters 0 to 5) in dimension-reduction (UMAP) analysis, with a comparable distribution of cells per cluster between normoxic and hypoxic cultures. Most clusters could be computationally assigned to a defined hematopoietic subpopulation, including progenitor cells (clusters 0 to 4) and a single transcriptionally defined HSC population (cluster 5). To assess the relative impact of normoxia and hypoxia on the HSC compartment, we performed gene set enrichment analysis (GSEA) of cells within HSC cluster 5 from each culture condition. A total of 32 genes were differentially expressed, and pathways indicative of cellular ER stress (unfolded protein response [UPR], heat shock protein [HSP] and chaperone) were significantly downregulated in hypoxia-treated cells relative to normoxic cultures (Fig. B). When examining expression of cluster 5 top differentially expressed genes across all cell clusters, we observed a more prominent upregulation of these genes within transcriptionally defined HSCs exposed to normoxia relative to more mature progenitors (Fig. C, red plots). Hypoxia lessened the cellular stress response in both progenitors and HSCs, but the mitigation was more apparent in the HSC population (Fig. C, grey plots), and decreased apoptosis was observed only within the HSC-enriched cluster 5 (Fig. D). These findings are consistent with several reports indicating that HSCs are more vulnerable to strong ER stress than downstream progenitors due to their lower protein folding capacity. In conclusion, we provide evidence that ex vivo culture of human adult CD34+ cells under hypoxic conditions enables a superior Delta1-mediated expansion of hematopoietic cells with LTR activity compared with normoxic cultures. Our data suggest a two-pronged mechanism by which optimal ectopic activation of Notch signaling in human HSCs promotes their self-renewal, and culture under hypoxia mitigates ER stress triggered by the increased proliferative demand, resulting in enhanced survival of expanding HSCs. This clinically feasible approach may be useful to improve outcomes of cellular therapeutics. Disclosures No relevant conflicts of interest to declare.

Lentiviral addition of βT87Q-globin, a modified β-globin with an anti-sickling mutation, is currently being used in gene therapy trials for sickle cell disease (SCD) and β-thalassemia patients. βT87Q-globin interferes with sickle hemoglobin (HbS) polymerization. Here, we generated the SCD mutation in an immortalized human erythroid cell line (HUDEP-2) to investigate the anti-sickling activity of βT87Q-globin. Sickle HUDEP-2 (sHUDEP-2) cells produced robust HbS after differentiation and sickled under deoxygenated conditions, comparable with SCD CD34+ progeny. Lentiviral transduction provided 9.5–26.8 pg/cell βT87Q-globin (R2 = 0.83) in a vector copy number (VCN)-dependent manner, resulting in a significant reduction of sickling ratios (R2 = 0.92). Interestingly, βT87Q-globin transduction markedly reduced endogenous βS-globin (R2 = 0.84) to an undetectable level (0.4–16.8 pg/cell) in sHUDEP-2 cells, as well as endogenous β-globin in human CD34+ cell-derived erythroid cells. RNA sequencing (RNA-seq) analysis with βT87Q-transduced sHUDEP-2 and human CD34+-derived cells revealed activation of inflammation- and proliferation-related programs, suggesting minimal changes in background gene expression except for βT87Q-globin expression and endogenous β/βS-globin suppression. In summary, using sHUDEP-2 and CD34+-derived cells, we demonstrated that lentiviral addition of βT87Q-globin strongly reduced endogenous β-/βS-globin expression, resulting in an anti-sickling effect. Our findings should be helpful to understand the anti-sickling effects of therapeutic genes in SCD gene therapy., Graphical Abstract

Unlike protein-coding genes, the majority of human long non-coding RNAs (lncRNAs) are considered non-conserved. Although lncRNAs have been shown to function in diverse pathophysiological processes in mice, it remains largely unknown whether human lncRNAs have such in vivo functions. Here, we describe an integrated pipeline to define the in vivo function of non-conserved human lncRNAs. We first identify lncRNAs with high function potential using multiple indicators derived from human genetic data related to cardiometabolic traits, then define lncRNA’s function and specific target genes by integrating its correlated biological pathways in humans and co-regulated genes in a humanized mouse model. Finally, we demonstrate that the in vivo function of human-specific lncRNAs can be successfully examined in the humanized mouse model, and experimentally validate the predicted function of an obesity-associated lncRNA, LINC01018, in regulating the expression of genes in fatty acid oxidation in humanized livers through its interaction with RNA-binding protein HuR., Majority of human long non-coding RNAs (lncRNAs) are not conserved in mouse. Here the authors identify metabolic trait-associated lncRNA genes and show a functional role of a non-conserved human lncRNA, LINC01018, in lipid metabolism using a humanized mouse model.

A growing number of long non-coding RNAs (lncRNAs) have emerged as vital metabolic regulators in research animals suggesting that lncRNAs could also play an important role in human metabolism. However, most human lncRNAs are non-conserved, vastly limiting our ability to identify human lncRNA metabolic regulators (hLMRs). As the sequence-function relation of lncRNAs has yet to be established, the identification of lncRNA metabolic regulators in animals often relies on their regulations by experimental metabolic conditions. But it is very challenging to apply this strategy to human lncRNAs because well-controlled human data are much limited in scope and often confounded by genetic heterogeneity. In this study, we establish an efficient pipeline to identify putative hLMRs that are metabolically sensitive, disease-relevant, and population applicable. We first progressively processed human transcriptome data to select human liver lncRNAs that exhibit highly dynamic expression in the general population, show differential expression in a metabolic disease population, and response to dietary intervention in a small disease cohort. We then experimentally demonstrated the responsiveness of selected hepatic lncRNAs to defined metabolic milieus in a liver-specific humanized mouse model. Furthermore, by extracting a concise list of protein-coding genes that are persistently correlated with lncRNAs in general and metabolic disease populations, we predicted the specific function for each hLMR. Using gain- and loss-of-function approaches in humanized mice as well as ectopic expression in conventional mice, we were able to validate the regulatory role of one non-conserved hLMR in cholesterol metabolism. Mechanistically, this hLMR binds to an RNA-binding protein, PTBP1, to modulate the transcription of cholesterol synthesis genes. In summary, our study provides a pipeline to overcome the variabilities intrinsic to human data to enable the efficient identification and functional definition of hLMRs. The combination of this bioinformatic framework and humanized murine model will enable broader systematic investigation of the physiological role of disease-relevant human lncRNAs in metabolic homeostasis.

BackgroundIn single-cell RNA-sequencing analysis, clustering cells into groups and differentiating cell groups by differentially expressed (DE) genes are 2 separate steps for investigating cell identity. However, the ability to differentiate between cell groups could be affected by clustering. This interdependency often creates a bottleneck in the analysis pipeline, requiring researchers to repeat these 2 steps multiple times by setting different clustering parameters to identify a set of cell groups that are more differentiated and biologically relevant.FindingsTo accelerate this process, we have developed IKAP—an algorithm to identify major cell groups and improve differentiating cell groups by systematically tuning parameters for clustering. We demonstrate that, with default parameters, IKAP successfully identifies major cell types such as T cells, B cells, natural killer cells, and monocytes in 2 peripheral blood mononuclear cell datasets and recovers major cell types in a previously published mouse cortex dataset. These major cell groups identified by IKAP present more distinguishing DE genes compared with cell groups generated by different combinations of clustering parameters. We further show that cell subtypes can be identified by recursively applying IKAP within identified major cell types, thereby delineating cell identities in a multi-layered ontology.ConclusionsBy tuning the clustering parameters to identify major cell groups, IKAP greatly improves the automation of single-cell RNA-sequencing analysis to produce distinguishing DE genes and refine cell ontology using single-cell RNA-sequencing data.

CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9)-mediated genome editing holds remarkable promise for the treatment of human genetic diseases. However, the possibility of off-target Cas9 activity remains a concern. To address this issue using clinically relevant target cells, we electroporated Cas9 ribonucleoprotein (RNP) complexes (independently targeted to two different genomic loci, the CXCR4 locus on chromosome 2 and the AAVS1 locus on chromosome 19) into human mobilized peripheral blood-derived hematopoietic stem and progenitor cells (HSPCs) and assessed the acquisition of somatic mutations in an unbiased, genome-wide manner via whole genome sequencing (WGS) of single-cell-derived HSPC clones. Bioinformatic analysis identified &gt, 20,000 total somatic variants (indels, single nucleotide variants, and structural variants) distributed among Cas9-treated and non-Cas9-treated control HSPC clones. Statistical analysis revealed no significant difference in the number of novel non-targeted indels among the samples. Moreover, data analysis showed no evidence of Cas9-mediated indel formation at 623 predicted off-target sites. The median number of novel single nucleotide variants was slightly elevated in Cas9 RNP-recipient sample groups compared to baseline, but did not reach statistical significance. Structural variants were rare and demonstrated no clear causal connection to Cas9-mediated gene editing procedures. We find that the collective somatic mutational burden observed within Cas9 RNP-edited human HSPC clones is indistinguishable from naturally occurring levels of background genetic heterogeneity.

The addition of a methyl group to, typically, a cytosine-guanine dinucleotide (CpG) creates distinct DNA methylation patterns across the genome that can regulate gene expression. Aberrant DNA methylation of CpG sites has been associated with many psychiatric disorders including bipolar disorder (BD) and suicide. Using the SureSelect(XT) system, Methyl-Seq, we investigated the DNA methylation status of CpG sites throughout the genome in 50 BD individuals (23 subjects who died by suicide and 27 subjects who died from other causes) and 31 nonpsychiatric controls. We identified differentially methylated regions (DMRs) from three analyses: (a) BD subjects compared to nonpsychiatric controls (BD-NC), (b) BD subjects who died by suicide compared to nonpsychiatric controls (BDS-NC), and (c) BDS subjects compared to BD subjects who died from other causes (BDS-BDNS). One DMR from the BDS-NC analysis, located in ARHGEF38, was significantly hypomethylated (23.4%) in BDS subjects. This finding remained significant after multiple testing (P(Bootstrapped) = 9.0 × 10(−3)), was validated using pyrosequencing, and was more significant in males. A secondary analysis utilized Ingenuity Pathway Analysis to identify enrichment in nominally significant DMRs. This identified an association with several pathways including axonal guidance signaling, calcium signaling, β-adrenergic signaling, and opioid signaling. Our comprehensive study provides further support that DNA methylation alterations influence the risk for BD and suicide. However, further investigation is required to confirm these associations and identify their functional consequences.

Purpose Antibody-Mediated Rejection (AMR) that occurs latter in the lung transplant (LTx) course show greater risk of chronic lung allograft dysfunction (CLAD) than early AMR. This suggest distinct mechanisms. This study leverages a large cohort and sensitive genomic tools to profile early and late AMR. Methods 435 LTx patients enrolled in two cohort studies were included. Endpoint and measures: CLAD-free survival is defined as being alive and CLAD-free. A committee adjudicated for both AMR and CLAD. Allograft injury at AMR was assessed as FEV1 decline and as plasma donor-derived cell-free DNA-%ddcfDNA, a validated biomarker. Then, bronchoalveolar lavage cells obtained at AMR (n=11) and no rejection control time points were subject to bisulfite sequencing; only AMR that met ISHLT probable AMR criteria was analyzed to reduce heterogeneity. Analyses: AMR was grouped as late (detected beyond 1 year post-transplant) or early AMR to compare donor-specific antibody (DSA) profile, allograft injury, and CLAD-free survival. Sequence reads for AMR and within subject control were compared to identify differentially methylated genes in early and late AMR. Results Early AMR (n=75) was more common than late AMR (n=47) over the 20 (IQR = 10 - 37) months follow-up. Both showed similar DSA profiles. However, late AMR showed higher FEV1 decline (0.8 L vs. 0.4L, p Conclusion Early and late AMR show distinct clinical and molecular profiles, suggesting the need for different treatment strategies. Validation studies are needed and may guide treatment decisions.

As genomes of a wider variety of animals become available, there is an increasing need for tools that can capture dynamic epigenetic changes in these animal models. The rat is one particular model animal where an epigenetic tool can complement many pharmacological and behavioral studies to provide insightful mechanistic information. To this end, we adapted the SureSelect Target Capture System (referred to as Methyl-Seq) for the rat, which can assess DNA methylation levels across the rat genome. The rat design targeted promoters, CpG islands, island shores, and GC-rich regions from all RefSeq genes. To implement the platform on a rat experiment, male Sprague Dawley rats were exposed to chronic variable stress for 3 weeks, after which blood samples were collected for genomic DNA extraction. Methyl-Seq libraries were constructed from the rat DNA samples by shearing, adapter ligation, target enrichment, bisulfite conversion, and multiplexing. Libraries were sequenced on a next-generation sequencing platform and the sequenced reads were analyzed to identify DMRs between DNA of stressed and unstressed rats. Top candidate DMRs were independently validated by bisulfite pyrosequencing to confirm the robustness of the platform. Results demonstrate that the rat Methyl-Seq platform is a useful epigenetic tool that can capture methylation changes induced by exposure to stress.

OBJECTIVE: Genes and the environment both play a major role in the risk for attempted suicide, and environments harboring stressors, such as early childhood abuse, have been linked to suicidal behavior. Such environments also disrupt the hypothalamic-pituitary-adrenal (HPA) axis pathway, which has been hypothesized to play a role in suicidal behavior. We investigated whether the risk for attempted suicide was attributable in part to the interaction between childhood physical and/or sexual abuse and genetic variation in 19 genes (±5 kb) integral to the HPA axis pathway. MATERIALS AND METHODS: Using the Genetic Association Information Network Bipolar Disorder and Translational Genomics Research Institute cohorts, we implemented PLINK's logistic regression-based 'interaction' approach to search for evidence of an interaction between 235 genotyped HPA axis single-nucleotide polymorphisms and early childhood abuse. Our study included 631 bipolar disorder suicide attempters and 657 bipolar disorder nonattempters with information on abuse. RESULTS: After correction for multiple testing, no significant interaction between the 235 HPA axis single-nucleotide polymorphisms and early childhood abuse was found. In our study, the strongest interaction was found with rs2664008 in the corticotropin-releasing hormone receptor 1 (CRHR1) gene, with a nominal interaction P-value of 1.22×10 and an interaction odds ratio of 0.47. CONCLUSION: Our findings suggest that further work and larger sample sizes are required to elucidate the link between early childhood abuse and the HPA axis in suicidal behavior. Language: en

Background.Previous studies suggest that the relationship between genetic risk and depression may be moderated by stressful life events (SLEs). The goal of this study was to assess whether SLEs moderate the association between polygenic risk of major depressive disorder (MDD) and depressive symptoms in older adults.Method.We used logistic and negative binomial regressions to assess the associations between polygenic risk, SLEs and depressive symptoms in a sample of 8761 participants from the Health and Retirement Study. Polygenic scores were derived from the Psychiatric Genomics Consortium genome-wide association study of MDD. SLEs were operationalized as a dichotomous variable indicating whether participants had experienced at least one stressful event during the previous 2 years. Depressive symptoms were measured using an eight-item Center for Epidemiologic Studies Depression Scale subscale and operationalized as both a dichotomous and a count variable.Results.The odds of reporting four or more depressive symptoms were over twice as high among individuals who experienced at least one SLE (odds ratio 2.19, 95% confidence interval 1.86–2.58). Polygenic scores were significantly associated with depressive symptoms (β= 0.21,p⩽ 0.0001), although the variance explained was modest (pseudor2= 0.0095). None of the interaction terms for polygenic scores and SLEs was statistically significant.Conclusions.Polygenic risk and SLEs are robust, independent predictors of depressive symptoms in older adults. Consistent with an additive model, we found no evidence that SLEs moderated the association between common variant polygenic risk and depressive symptoms.

Tumor-derived Copy Number Variations (CNVs) are among the most important genomic aberrations in cancers. Since a CNV amplification is often associated with oncogene activation, and a CNV deletion is frequently attributed to the gene inactivation, an accurate detection of CNVs plays a crucial role in cancer diagnosis and treatment. In this study, using the next generation sequencing, we systematically interrogated somatic CNVs in paired tumor-normal cell lines to identify factors affecting detection reproducibility and accuracy. Whole-genome and whole-exome sequencing were carried out at six sequencing centers followed by processing with six CNV callers to evaluate their reproducibility. Different types of samples with varying input amount and tumor purity were processed using multiple library construction protocols and read depths. We compared the consistency of reference replicates, the effect of experimental, technical, and biological confounding factors, and benchmarked our callers using cytogenetic array. Our evaluation was based on two approaches; bin-based and gene-based approach. The bin-based comparison used a sliding window of 10 Kb, while gene-based comparison used segments at the gene level. Our evaluations indicate variations among CNV calls are mainly driven by callers and less by the sequencing centers. In addition to caller effect, PCA analyses also show site-specific effect, largely pairwise distances on the PC plot for pairs between different centers than for those within the same centers. Among confounding factors, namely FFPE, library concentration, and tumor purity with several sequencing depths, we report that tumor purity has a dominant and major effect in caller’s performance. PCA analysis shows low tumor purity ( Citation Format: Yun-Ching Chen, Fayaz Seifuddin, Cu Nguyen, Chunhua Yan, Qingrong Chen, Wenming Xiao, Mehdi Pirooznia, Daoud Meerzaman. Critical Assessment of CNV Calling Using Next Generation Sequencing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3521.

Purpose AMR show strikingly similar molecular mechanisms (chronic inflammation, fibrogenesis, and others processes) to conditions that accelerate lung aging. Clinically, both AMR and age acceleration manifest as progressive loss of lung function leading us to hypothesize that AMR is associated with age acceleration. Age acceleration triggers signature methylation changes at cytosine-guanosine (CpGs) motifs of “aging” genes. Thus, to test this hypothesis, we used unbiased bisulfite sequencing. Methods Six lung transplant patients with AMR (positive allograft dysfunction, DSA and histopathology and/or C4d) were identified. Two bronchoalveolar (BAL) samples were collected from each patient, one pre-AMR control (no rejection, no infection) and one at AMR diagnosis. BAL cells were used for DNA isolation, bisulfite treatment, and sequencing. Sequences were analyzed via a custom-built computation workflow (bismark, bsseq, bumphunter) that assigns CpGs to DNA regions, normalizes data for cell composition, performs paired analysis to identify differentially methylated regions (DMRs), and maps the DMRs to genes for pathway enrichment analysis. Thresholds for CpG coverage (6X) and DMR mean difference (10%) were arbitrarily selected. P-values were corrected for multiple analyses. Results We identified 900K DMRs between AMR and control. Average DMR length was 238 base pairs with median 4.7 CpGs per DMR (range 3-64). 38.8K DMRs showed 10% or higher methylation difference between AMR and control, with 67% of the DMRs mapped to genes within 1 Killobase. “Aging” genes were overrepresented (q=2.880 × 10−13): genes that promote lung age acceleration (n=370) were predominantly hypo-methylated in AMR, while genes that inhibit lung age acceleration (n=454) were predominantly hyper-methylated. Antibody-mediated pathways such as macrophage activation, Fc-gamma-mediated cell-death, and cytotoxic T-cell activation were also overrepresented (q=0.0007 - 0.0040). Conclusion Both antibody-mediated pathways and “aging” genes were differentially methylated in AMR suggesting epigenetic regulation of these processes and a strong association between AMR and age acceleration. Future studies are needed to validate these findings and assess whether age acceleration contribute to the progressive loss of lung function often observed with AMR.

Numerous candidate gene association studies of bipolar disorder (BP) have been carried out, but the results have been inconsistent. Individual studies are typically underpowered to detect associations with genes of small effect sizes. We conducted a meta-analysis of published candidate gene studies to evaluate the cumulative evidence. We systematically searched for all published candidate gene association studies of BP. We then carried out a random-effects meta-analysis on all polymorphisms that were reported on by three or more case-control studies. The results from meta-analyses of these genes were compared with the findings from a recent mega-analysis of eleven genome-wide association studies (GWAS) in BP performed by the Psychiatric GWAS Consortium (PGC). A total of 487 articles were included in our review. Among these, 33 polymorphisms in 18 genes were reported on by three or more case-control studies and included in the random-effects meta-analysis. Polymorphisms in BDNF, DRD4, DAOA, and TPH1, were found to be nominally significant with a P-value 0.05. However, none of the findings were significant after correction for multiple testing. Moreover, none of these polymorphisms were nominally significant in the PGC-BP GWAS. A number of plausible candidate genes have been previously associated with BP. However, the lack of robust findings in our review of these candidate genes highlights the need for more atheoretical approaches to study the genetics of BP afforded by GWAS. The results of this meta-analysis and from other on-going genomic experiments in BP are available online at Metamoodics (http://metamoodics.igm.jhmi.edu).

Mood disorders are highly heritable forms of major mental illness. A major breakthrough in elucidating the genetic architecture of mood disorders was anticipated with the advent of genome-wide association studies (GWAS). However, to date few susceptibility loci have been conclusively identified. The genetic etiology of mood disorders appears to be quite complex, and as a result, alternative approaches for analyzing GWAS data are needed. Recently, a polygenic scoring approach that captures the effects of alleles across multiple loci was successfully applied to the analysis of GWAS data in schizophrenia and bipolar disorder (BP). However, this method may be overly simplistic in its approach to the complexity of genetic effects. Data mining methods are available that may be applied to analyze the high dimensional data generated by GWAS of complex psychiatric disorders.We sought to compare the performance of five data mining methods, namely, Bayesian networks, support vector machine, random forest, radial basis function network, and logistic regression, against the polygenic scoring approach in the analysis of GWAS data on BP. The different classification methods were trained on GWAS datasets from the Bipolar Genome Study (2191 cases with BP and 1434 controls) and their ability to accurately classify case/control status was tested on a GWAS dataset from the Wellcome Trust Case Control Consortium.The performance of the classifiers in the test dataset was evaluated by comparing area under the receiver operating characteristic curves. Bayesian networks performed the best of all the data mining classifiers, but none of these did significantly better than the polygenic score approach. We further examined a subset of single-nucleotide polymorphisms (SNPs) in genes that are expressed in the brain, under the hypothesis that these might be most relevant to BP susceptibility, but all the classifiers performed worse with this reduced set of SNPs. The discriminative accuracy of all of these methods is unlikely to be of diagnostic or clinical utility at the present time. Further research is needed to develop strategies for selecting sets of SNPs likely to be relevant to disease susceptibility and to determine if other data mining classifiers that utilize other algorithms for inferring relationships among the sets of SNPs may perform better.

Genome-wide association studies (GWAS) have identified several susceptibility loci for bipolar disorder (BP), most notably ANK3. However, most of the inherited risk for BP remains unexplained. One reason for the limited success may be the genetic heterogeneity of BP. Clinical sub-phenotypes of BP may identify more etiologically homogeneous subsets of patients, which can be studied with increased power to detect genetic variation. Here, we report on a mega-analysis of two widely studied sub-phenotypes of BP, age at onset and psychotic symptoms, which are familial and clinically significant. We combined data from three GWAS: NIMH Bipolar Disorder Genetic Association Information Network (GAIN-BP), NIMH Bipolar Disorder Genome Study (BiGS), and a German sample. The combined sample consisted of 2,836 BP cases with information on sub-phenotypes and 2,744 controls. Imputation was performed, resulting in 2.3 million SNPs available for analysis. No SNP reached genome-wide significance for either sub-phenotype. In addition, no SNP reached genome-wide significance in a meta-analysis with an independent replication sample. We had 80% power to detect associations with a common SNP at an OR of 1.6 for psychotic symptoms and a mean difference of 1.8 years in age at onset. Age at onset and psychotic symptoms in BP may be influenced by many genes of smaller effect sizes or other variants not measured well by SNP arrays, such as rare alleles.

Sickle cell disease (SCD) is an inherited hemoglobinopathy characterized by hemolysis and intermittent acute pain with multi-organ damage. Previously, we showed that acute pain in SCD was associated with >10-fold increases in cell-free DNA (cfDNA) when compared to steady state, that were significantly reduced during hydroxyurea therapy. Apoptosis, necrotic cell death and lysis of intact cells in the blood stream have been proposed as sources of plasma cfDNA. Here, we explored if the cfDNA increases could have a role in inflammation, a constant pathological feature of SCD. cfDNA was extracted using QIAamp MinElute ccfDNA Kit (Qiagen), from the platelet-poor plasma processed within 30 minutes from the blood drawn in EDTA tubes, and analyzed using whole genome sequencing (WGS) and targeted quantitative PCR (qPCR). SCD patients are defined as in acute pain if there is no evident cause other than SCD, for which the patient needs hospitalization, either as in- or outpatient, and is treated with parenteral narcotics. Steady state was defined as the period from at any time 8 weeks prior to or after a crisis. A cross-sectional study of 8 healthy controls and 34 SCD patients (18 steady-state; 16 crisis) mapped WGS reads showed significantly higher proportion of cell-free mitochondrial DNA (cf-mtDNA) compared to nuclear cfDNA (cf-nDNA) in SCD patients compared with healthy controls (Fig 1A: steady-state: 14 fold; crisis: 11 fold; p = 0.0001). We used targeted qPCR to quantify both cf-nDNA and cf-mtDNA in another cross-sectional cohort of 13 healthy controls and 92 patients (72 steady-state, 20 crisis) as well as 18 paired HbSS patients (steady-state and crisis) samples with 10 healthy controls. The nuclear reference genes used were GAPDH and TERT and mitochondrial genes were MT-ND1 and MT-ND6. While cf-nDNA (TERT) was significantly increased (> 3.5 fold, p = 0.0251; Fig 1B) in SCD patients compared with healthy controls only during crises, significantly higher levels of cf-mtDNA over cf-nDNA were observed in SCD patients compared with healthy volunteers in both steady-state and crises (Fig 1C: MT-ND1/GAPDH: steady-state >19 fold, crisis > 8 fold; MT-ND1/TERT: steady-state > 8 fold, crisis > 7 fold; MT-ND6/GAPDH: steady-state > 7 fold, crisis > 3 fold; MT-ND6/TERT: steady-state > 4 fold; crisis > 4 fold; p < 0.05). In the paired samples, cf-nDNA (GAPDH andTERT) was significantly increased (> 3 fold; Fig 1D-E) in crisis compared to steady-state (p < 0.05). The differential increase in cf-mtDNA (cf-mtDNA:cf-nDNA ratio) levels in these patients during crises, were significantly higher compared with healthy controls (Fig 1F: MT-ND1/GAPDH: steady-state >9 fold, crisis > 8 fold; MT-ND1/TERT: steady-state > 8 fold, crisis > 9 fold; MT-ND6/GAPDH: steady-state > 8 fold, crisis > 8 fold; MT-ND6/TERT: steady-state > 8 fold; crisis > 7 fold; p < 0.005). Using confocal microscopy and mitochondrial-specific dyes (MitoTracker Green and TMRM), we show that substantial numbers of red blood cells from SCD patients retain their mitochondria in the circulation. We next explored if the elevated cf-mtDNA in SCD could contribute to its pathophysiology, via activating neutrophils to form neutrophil extracellular traps (NETs), a recognized immunological response in inflammation. Initially, we confirmed that mtDNA can induce NETosis by treating neutrophils from healthy donors with mtDNA isolated from human platelets. mtDNA consistently induced a robust NETs response (N=8) while genomic nuclear DNA did not cause any NETosis. SCD plasma containing high levels of cf-mtDNA also caused a strong NETosis response while plasma from healthy donors did not (N=11). Cytosolic adaptor STING has a central role in sensing of cytosolic double stranded DNA. We sought to determine if the downstream STING-TBK1-IRF3 pathway is associated with the mtDNA-mediated formation of NETs. We inhibited the catalytic activity of the STING downstream effector TBK1 with BX795 prior to treating neutrophils with cf-mtDNA-containing plasma (N=5). The TBK1 inhibition consistently reduced the NETs response by at least 70% confirming that cytosolic DNA sensors are involved in promoting mtDNA-mediated formation of NETs. Our findings suggest that cf-mtDNA induces NETosis contributing to the pathological sterile inflammation in SCD patients. Continual release of these mitochondrial DAMPs in hemolysis may serve as key link between inflammation and organ damage in SCD. Disclosures No relevant conflicts of interest to declare.

Epigenetic studies that utilize peripheral tissues to identify molecular substrates of neuropsychiatric disorders rely on the assumption that disease-relevant, cellular alterations that occur in the brain are mirrored and detectable in peripheral tissues such as blood. We sought to test this assumption by using a mouse model of Cushing's disease and asking whether epigenetic changes induced by glucocorticoids can be correlated between these tissue types.Mice were treated with different doses of glucocorticoids in their drinking water for four weeks to assess gene expression and DNA methylation (DNAm) changes in the stress response gene Fkbp5.Significant linear relationships were observed between DNAm and four-week mean plasma corticosterone levels for both blood (R(2)=0.68, P=7.1×10(-10)) and brain (R(2)=0.33, P=0.001). Further, degree of methylation change in blood correlated significantly with both methylation (R(2)=0.49, P=2.7×10(-5)) and expression (R(2)=0.43, P=3.5×10(-5)) changes in hippocampus, with the notable observation that methylation changes occurred at different intronic regions between blood and brain tissues.Although our findings are limited to several intronic CpGs in a single gene, our results demonstrate that DNA from blood can be used to assess dynamic, glucocorticoid-induced changes occurring in the brain. However, for such correlation analyses to be effective, tissue-specific locations of these epigenetic changes may need to be considered when investigating brain-relevant changes in peripheral tissues.

Mood disorders, including Major Depression (MD) and Bipolar Disorder (BP), are among the most common psychiatric disorders1. Although genetic factors play an important role in their etiology2, 3, the heritability of these disorders remains largely unexplained. Due to advances in high-throughput genomic technologies, it is becoming increasingly feasible to investigate the genetic architecture of these disorders at an unprecedented resolution. The challenge is how to make sense of the enormous flood of data generated by the diverse genomic studies that use these new technologies. It is essential to integrate the findings from such studies in order to develop a more comprehensive understanding of the genetic contribution to these disorders that can be readily translated into new and more rational therapeutic interventions. Towards this end, we have developed a bioinformatics resource called Metamoodics (www.metamoodics.org), which integrate results from various genomic studies of mood disorders and enhance their interpretation by placing them within an enriched genomic context. Metamoodics was created as a resource for the research community to explore what is currently known about the genetic contribution to mood disorders. Metamoodics synthesizes data from existing genome-wide linkage, expression and association studies for both MD and BP. It brings together results from up-to-date meta- or mega-analyses of these studies, and presents them in both tabular and graphical modes. The genome-wide linkage data comes from among the largest and most comprehensive of such studies with MD and BP. Data for BP comes from a mega-analysis carried out with 972 informative pedigrees of European ancestry pooled from eight research groups in North America and the United Kingdom3. Linkage statistics for twelve different phenotype-by-genotype models were calculated for a genome-wide panel of 6090 SNPs. For MD, data from the Genetics of Recurrent Early-Onset Major Depression (GenRED) collaborative are provided4. This included data on 418 microsatellite markers genotyped in 656 families consisting of 1,494 all possible informative affective relative pairs. Data for genome-wide association studies (GWAS) were obtained from the psychiatric GWAS consortium (PGC). For BP, the sample included 7,481 cases and 9,250 controls, all of European ancestry, with data on ~2.5M genotyped and/or imputed SNPs5. Data on MD consisted of more than 1.2 million SNPs in 9,240 cases and 9,519 controls of recent European ancestry6. Gene expression data was obtained through a systematic review of studies on BP (n=13) and MD (n=7) using post-mortem brain tissue. Mega-analyses of the most comprehensive and rigorous of these studies were carried out using samples from all regions of the brain, the pre-frontal cortex, and the hippocampus, where sufficient data was available7. Finally, Metamoodics includes a comprehensive meta-analysis of published candidate gene association studies of BP. Data on 33 polymorphisms in 18 genes reported on by three or more case-control studies were included in the meta-analysis8. A similar meta-analysis for MD is forthcoming. Metamoodics includes a variety of online applications and tools for visualization and further analysis of the genomics data. Data visualization makes use of NCBI SeqView API and a local mirror of the UCSC genome browser. The results can be queried by gene or chromosomal position to obtain either a gene level view via chromosomal or regional plots, or a more global view via the genome browser to investigate the genomic context of the findings. User-defined data can be uploaded to the genome browser using the custom track option to visualize alongside the Metamoodics tracks. Analysis tools include SVAw9 for surrogate variable analysis, METAw for meta-analysis and a gene expression package for individual and mega analysis of expression data. Metamoodics presents the latest results from genomic studies of mood disorders in a user-friendly web interface that enables users to rapidly compare findings from different experimental platforms across the genome, as well as drill down to specific findings to visualize how these relate to underlying genomic structure and function. Metamoodics provides the entire set of results of a given study rather than just significant ones, thus providing a complete and unbiased report of the findings. We will continue to update Metamoodics with findings from the latest genomic experiments of mood disorders, such as whole exome or genome sequencing and epigenetic studies. Metamoodics is a vital bioinformatics tool for investigating the genetic etiology of mood disorders that will only grow more powerful as new data are added.

Background Numerous genome-wide gene expression studies of bipolar disorder (BP) have been carried out. These studies are heterogeneous, underpowered and use overlapping samples. We conducted a systematic review of these studies to synthesize the current findings. Methods We identified all genome-wide gene expression studies on BP in humans. We then carried out a quantitative mega-analysis of studies done with post-mortem brain tissue. We obtained raw data from each study and used standardized procedures to process and analyze the data. We then combined the data and conducted three separate mega-analyses on samples from 1) any region of the brain (9 studies); 2) the prefrontal cortex (PFC) (6 studies); and 3) the hippocampus (2 studies). To minimize heterogeneity across studies, we focused primarily on the most numerous, recent and comprehensive studies. Results A total of 30 genome-wide gene expression studies of BP done with blood or brain tissue were identified. We included 10 studies with data on 211 microarrays on 57 unique BP cases and 229 microarrays on 60 unique controls in the quantitative mega-analysis. A total of 382 genes were identified as significantly differentially expressed by the three analyses. Eleven genes survived correction for multiple testing with a q-value FKBP5 and WFS1, which have been previously implicated in mood disorders. Pathway analyses suggested a role for metallothionein proteins, MAP Kinase phosphotases, and neuropeptides. Conclusion We provided an up-to-date summary of results from gene expression studies of the brain in BP. Our analyses focused on the highest quality data available and provided results by brain region so that similarities and differences can be examined relative to disease status. The results are available for closer inspection on-line at Metamoodics [http://metamoodics.igm.jhmi.edu/], where investigators can look up any genes of interest and view the current results in their genomic context and in relation to leading findings from other genomic experiments in bipolar disorder.

Recent schizophrenia research supports a model wherein aberrant brain changes in late-adolescence contribute to the onset and early progression of disease.1 To further examine this model, longitudinal studies of genetic high-risk subjects, including those in prodromal stage, have recently been conducted.2 Parallel studies evaluating patients with recent-onset schizophrenia are growing in number.3 Nonetheless, almost all these studies are limited to clinical and neuropsychological characterization, and to brain imaging. Therefore, the molecular mechanisms underlying these dynamic changes remain elusive. In order to address this fundamental question with better molecular understanding, we have examined the cerebrospinal fluid (CSF) from patients with recent-onset schizophrenia (within the first five years of disease) and have compared these samples to those from age-matched healthy controls and patients with chronic schizophrenia (five or more years of schizophrenia) (Supplementary Table 1). Building on the hypothesis that oxidative stress and associated neuroinflammatory response may play a role in this dynamic process,4 we measured the levels of 14 selected molecules (Supplementary Table 2). Here we report the novel finding of a dramatically reduced level of soluble superoxide dismutase-1 (SOD1) in CSF from patients with recent-onset schizophrenia in contrast to samples from age-matched healthy controls (Table 1, Supplementary Figure 1). Furthermore, the level of CSF soluble SOD1 from recent-onset patients is lower than that from patients with chronic schizophrenia. To our knowledge, this is the first report of decreased CSF SOD1 in recent-onset schizophrenia. We also highlight that while the sample size of patients with one year or less disease is small, the absolute concentrations of soluble SOD1 are most robustly decreased in this cohort. We speculate that the decrease in soluble SOD1 between patients with one year or less disease and age-matched healthy controls is limited in significance by the small sample size. Table 1 Comparison of CSF soluble SOD1 concentration between patients with recent-onset schizophrenia (less than five years disease) grouped by disease duration and age-matched healthy controls. While our reported observations require replication in a larger sample, this study implies two innovative conceptual contributions. First, the reduction of soluble SOD1 may directly underlie oxidative stress at the onset of schizophrenia through decreased availability of this important antioxidant enzyme. We further note that this decrease in CSF soluble SOD1 concentration could be a secondary effect of another pro-oxidative process. Nevertheless, this ultimate decrease in soluble SOD1 is likely to facilitate overall oxidative stress. Thus, we provide further evidence of the “oxidative stress hypothesis” in schizophrenia. Second, we note the possibility that a decrease in CSF soluble SOD1 may reflect an increase in “insoluble” SOD1. This is analogous to decreased Aβ1-42 in CSF from patients with Alzheimer’s disease reflecting insoluble Aβ1-42 and senile plaques.5 Likewise, SOD1 is amyloidogenic and can be associated with brain disorders, such as amyotrophic lateral sclerosis (ALS).6 We wish to recall that aggregate formation in Huntington’s disease and other brain disorders has been discovered only after specific probing of target molecules, such as Huntingtin detection using a specific antibody.7 Therefore, it is crucial to now explore insoluble SOD1 in autopsied brains or biopsied cells (e.g. induced neurons from fibroblasts, olfactory neurons) from patients with recent-onset schizophrenia, and such future studies may utilize antibodies against insoluble forms of SOD1.8 A role of misfolded protein in schizophrenia has also been suggested by studies stemming from genetic susceptibility factors. Korth and associates9 reported the recruitment of Dysbindin protein to cell-invasive DISC1 aggresomes, suggesting the important convergence of two promising genetic risk factors and the significance of protein insolubility in cases of schizophrenia. The levels of CSF soluble SOD1 are not significantly different between chronic cases and matched healthy controls (data not shown). The possible contrast in SOD1 between recent-onset schizophrenia and chronic cases may be addressed in follow-up studies with larger sample size. It is possible that transient downregulation around the onset of schizophrenia might play an important pathophysiological role. Of note, some studies suggest that neuroleptic medication might increase plasma or serum SOD levels,10 although levels between peripheral blood and CSF are not necessarily correlated. In this report with one exception, all patients were on medication at the time of CSF acquisition. In summary, we report diminished CSF soluble SOD1 in cases of recent-onset schizophrenia and discuss this observation as supporting the previously proposed role of “oxidative stress” in the pathophysiology and onset of this disease. Increased oxidative stress can lead to synaptic deterioration and interneuron deficits relevant to the pathophysiology of schizophrenia. Furthermore, this observation may also be an entry point for other working hypotheses, such as those of SOD1 protein misfolding and aberrant control of proteolysis, which prompt further investigation.

We report the results of a high-density attempted suicide association study of the X chromosome, which genotyped 23,141 SNPs on 983 attempters and 1143 non-attempters and generated modest evidence for association for SH3KBP1 ( P =1.07×10 −4 ) and GRIA3 ( P =4.01×10 −4 ). These findings highlight the need for larger sample sets and meta-analytic approaches.

Comprehensive High-throughput Arrays for Relative Methylation (CHARM) was recently developed as an experimental platform and analytic approach to assess DNA methylation (DNAm) at a genome-wide level. Its initial implementation was for human and mouse. We adapted it for rat and sought to examine DNAm differences across tissues and brain regions in this model organism. We extracted DNA from liver, spleen, and three brain regions: cortex, hippocampus, and hypothalamus from adult Sprague Dawley rats. DNA was digested with McrBC, and the resulting methyl-depleted fraction was hybridized to the rat CHARM array along with a mock-treated fraction. Differentially methylated regions (DMRs) between tissue types were detected using normalized methylation log-ratios. In validating 24 of the most significant DMRs by bisulfite pyrosequencing, we detected large mean differences in DNAm, ranging from 33-59%, among the most significant DMRs in the across-tissue comparisons. The comparable figures for the hippocampus vs. hypothalamus DMRs were 14-40%, for the cortex vs. hippocampus DMRs, 12-29%, and for the cortex vs. hypothalamus DMRs, 5-35%, with a correlation of r(2) = 0.92 between the methylation differences in 24 DMRs predicted by CHARM and those validated by bisulfite pyrosequencing. Our adaptation of the CHARM array for the rat genome yielded highly robust results that demonstrate the value of this method in detecting substantial DNAm differences between tissues and across different brain regions. This platform should prove valuable in future studies aimed at examining DNAm differences in particular brain regions of rats exposed to environmental stimuli with potential epigenetic consequences.

Epidemiological studies, such as family, twin, and adoption studies, demonstrate the presence of a heritable component to both attempted and completed suicide. Some of this heritability is accounted for by the presence of comorbid psychiatric disorders, but the evidence also indicates that a portion of this heritability is specific to suicidality. The serotonergic system has been studied extensively in this phenotype, but findings have been inconsistent, possibly due to the presence of multiple susceptibility variants and/or gene-gene interactions. In this study, we genotyped 174 tag and coding single nucleotide polymorphisms (SNPs) from 17 genes within the serotonin pathway on 516 subjects with a major mood disorder and a history of a suicide attempt (cases) and 515 healthy controls, with the goal of capturing the common genetic variation across each of these candidate genes. We tested the 174 markers in single-SNP, haplotype, gene-based, and epistasis analyses. While these association analyses identified multiple marginally significant SNPs, haplotypes, genes, and interactions, none of them survived correction for multiple testing. Additional studies, including assessment in larger sample sets and deep resequencing to identify rare causal variants, may be required to fully understand the role that the serotonin pathway plays in suicidal behavior.

The heritable component to attempted and completed suicide is partly related to psychiatric disorders and also partly independent of them. Although attempted suicide linkage regions have been identified on 2p11-12 and 6q25-26, there are likely many more such loci, the discovery of which will require a much higher resolution approach, such as the genome-wide association study (GWAS). With this in mind, we conducted an attempted suicide GWAS that compared the single-nucleotide polymorphism (SNP) genotypes of 1201 bipolar (BP) subjects with a history of suicide attempts to the genotypes of 1497 BP subjects without a history of suicide attempts. In all, 2507 SNPs with evidence for association at P0.001 were identified. These associated SNPs were subsequently tested for association in a large and independent BP sample set. None of these SNPs were significantly associated in the replication sample after correcting for multiple testing, but the combined analysis of the two sample sets produced an association signal on 2p25 (rs300774) at the threshold of genome-wide significance (P=5.07 × 10(-8)). The associated SNPs on 2p25 fall in a large linkage disequilibrium block containing the ACP1 (acid phosphatase 1) gene, a gene whose expression is significantly elevated in BP subjects who have completed suicide. Furthermore, the ACP1 protein is a tyrosine phosphatase that influences Wnt signaling, a pathway regulated by lithium, making ACP1 a functional candidate for involvement in the phenotype. Larger GWAS sample sets will be required to confirm the signal on 2p25 and to identify additional genetic risk factors increasing susceptibility for attempted suicide.

Family, twin, and adoption studies provide convincing evidence for a genetic contribution to suicidal behavior. The heritability for suicidal behavior depends in part on the transmission of psychiatric disorders, such as mood disorders and substance use disorders, but is also partly independent of them. Three linkage studies using the attempted suicide phenotype in pedigrees with bipolar disorder, major depression, or alcoholism have provided consistent evidence that 2p11-12 harbors a susceptibility gene for attempted suicide. A microarray expression study using postmortem brain samples has implicated a gene from the 2p11-12 candidate region, the trans-Golgi network protein 2 (TGOLN2) gene, as being consistently up-regulated in suicide cases as compared to controls. Here, we present a TGOLN2 case-control association study using nine single nucleotide polymorphisms (SNPs). These nine SNPs, which include seven tag SNPs and two coding SNPs, have been genotyped in 517 mood disorder subjects with a history of attempted suicide and 515 normal controls. Allelic and genotypic analyses of the case-control sample did not provide evidence for association with the attempted suicide phenotype. Eight of the nine SNPs provided supportive evidence for association (P-values ranging from 0.008 to 0.03) when we compared the attempted suicide cases with a history of alcoholism to the attempted suicide cases without a history of alcoholism. However, this association finding was not replicated in an independent sample. Taken together, these analyses do not provide support for the hypothesis that common genetic variation in TGOLN2 contributes significantly to the risk for attempted suicide in subjects with major mood disorders.