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COVID-19 is an infectious disease caused by the virus SARS-CoV-2, which was first described at the end of 2019. Since then, it has affected a growing portion of the world's population because of its high transmissibility. Most patients are asymptomatic or present with mild symptoms, but approximately 5-10% of cases can develop more serious manifestations, such as severe acute respiratory syndrome, acute kidney injury, shock, myocardial injury and even death. These features seem to occur more commonly in patients with essential hypertension, diabetes mellitus, obesity and chronic pulmonary disease. However, there are few studies that clarify the natural history of the disease and its broad clinical spectrum owing to the fact that it is a new entity. Since individuals with malignancies tend to present some degree of immunological deficiency and are more prone to opportunistic infections, especially those being treated with immunosuppressive drugs, it is possible that this group has a higher incidence of COVID-19. The current recommendations of oncology specialists advise to postpone treatments and to use less toxic drugs when possible. However, we still do not know how much these measures will affect in cancer mortality. Also, the incidence of COVID-19 in this population remains undetermined. We do not know if infectious symptoms are a good parameter to motivate these therapeutic changes or if there is benefit to test asymptomatic patients. In this context, this research submitted 100 patients with hematological malignancies or solid tumors on chemotherapy at the Ribeirão Preto Medical School of the University of São Paulo's Hospital, asymptomatic for COVID-19, to RT PCR to determine the SARS-CoV-2 infection incidence in this population. Only two patients were diagnosed with COVID-19. Both had gastrointestinal cancer. One of them developed symptoms, but none presented severe manifestations. Both had their treatment postponed initially and reinitiated after the appropriate period of isolation. Hence, we believe that it's reasonable not to test every asymptomatic patient when the resource for that is scarce, prioritizing those at greater risk of infection and those more prone to severe outcomes as long as the appropriate preventive measures are being taken. Disclosures Calado: Team Telomere, Inc.: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Instituto Butantan: Consultancy; Alexion Brasil: Consultancy; AA&MDS International Foundation: Research Funding; Novartis Brasil: Honoraria.

Single Nucleotide Polymorphisms (SNPs) identified through genome-wide association studies (GWAS) provide insight into the mechanism of human genetic diseases, and majority of functional GWAS mutations target genomic regulatory elements. During erythroid differentiation of human CD34+ cells, we mapped regulatory DNA elements (enhancers and open chromatin regions) by H3K27Ac ChIP-seq and ATAC-seq, and studied the SNPs that reside within these DNA regulatory elements. We followed genomic binding of lineage restricted GATA transcription factors and also chose to examine the binding of the BMP signal responsive transcription factor SMAD1 in CD34+ cells during erythropoiesis. By overlapping their genomic occupancy with stage-matched RNA-seq, we found that SMAD1, in association with GATA-factors, serves as marker of genes responsible for differentiation at every step of erythropoiesis. ChIP-seq for other crucial signaling transcription factors, such as WNT-responsive and TGFb-responsive factors (TCF7L2 and SMAD2, respectively) demonstrated a remarkable co-existence of such factors at GATA+SMAD1 co-bound regions nearby stage-specific genes. We defined such regions as "Transcriptional Signaling Centers (TSC)" where multiple signaling transcription factors converge with master transcription factors to determine optimum stage-specific gene expression in response to growth factors. Our bioinformatics-algorithms demonstrated that PU1 and FLI1 binding sites were present in progenitor-specific TSCs whereas KLF1 and NFE2 sites were enriched in TSCs of red blood cells. We performed CRISPR-CAS9 mediated perturbations of each of the PU1, GATA and SMAD1 motifs separately in a representative progenitor TSC in K562 and HUDEP2 cells. Similar to loss of PU1 and GATA motifs, loss of SMAD1 motif selectively inhibited expression of the associated gene and showed defects in erythroid differentiation, demonstrating that TSCs are important to provide optimum gene expression and proper erythroid differentiation. To determine if such TSCs are targeted by GWAS mutations, we have studied 1270 lead and additional 27,799 SNPs in linkage disequilibrium with lead SNPs that are associated with six critical red blood cell traits - hemoglobin concentration (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) and red blood cell count (RBC). Surprisingly, we observed that, out of the 3831 "functional" SNPs that fall within non-exonic H3K27Ac enhancers, while only 5% (188) of RBC-SNPs target only blood-master-transcription-factor motifs, at least 48% (1821) of them reside on various signaling pathway associated transcription factor motifs including SMADs (BMP/TGFb signaling), RXR/ROR (nuclear receptor signaling), FOXO/FOXA (FOX signaling), CREBs (cAMP signaling) and TCF7L2 (WNT signaling). Additionally, these RBC-trait-SNPs are specifically enriched in GATA+SMAD1 co-bound TSCs and fall within signaling factor binding sites. We validated such SNPs that target SMAD-motifs. The SNP rs9467664 is associated with the MCV-trait near HIST1H4A, a gene that increases in expression during differentiation. Using gel-shift assay, we found that SMAD1 binding is compromised when the major allele T changes to minor allele A under MCV-trait. Remarkably, eQTL analysis using microarray gene expression profiles of peripheral blood obtained from the Framingham Heart Studies revealed that expression of HIST1H4A is significantly more in a population with T-allele than that with A-allele. This demonstrates that inhibition of SMAD1 binding by the SNP causes a loss of allele-specific HIST1H4A expression. Another MCV-associated SNP rs737092 targets a SMAD motif within an erythroid-specific TSC near RBM38 gene. T-allele, in comparison with C-allele, that retains SMAD1 binding showed more expression in luciferase-based reporter assays specifically under BMP stimulation suggesting that rs737092 compromise BMP-responsiveness. Taken together, our study provides the first evidence that naturally occurring GWAS variations directly impact gene expression from signaling centers by modulating binding of signaling transcription factors under stimulation. Such aberrant signaling events over time could lead to "signalopathies", ultimately resulting in phenotypic variations of RBC traits. Disclosures Abraham: Syros Pharmaceuticals: Equity Ownership. Young:Omega Therapeutics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Syros Pharmaceuticals: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Camp4 Therapeutics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

Abstract 4611 The PML-RARα fusion protein plays a pivotal role in acute promyelocytic leukemia (APL) genesis and one of the mechanisms through which this fusion protein exerts its activity is the epigenetic suppression of gene transcription. PML-RARα physically interacts with epigenetic-modifying enzymes including DNA methyltransferases leading to hypermethylation and silencing of target genes. Nevertheless, the nature of the genes critical to APL oncogenesis is unclear, particularly in humans. We compared the methylation patterns at diagnosis and at remission in four patients with APL and four healthy controls. In order to isolate myeloid progenitors in the bone marrow (BM) samples from patients at remission and healthy controls, CD117 positive cells were sorted. Genomic DNA was sodium bisulfite converted and methylation analysis was performed using Illumina HumanMethylation27 BeadChip Platform (which analyzes methylation sites, including promoter and methylation hotspots of over 14,000 genes). DNA methylation values from the bead array hybridizations were scored as b-values. The high-variance features (> 0.05) were identified and filtered, and the three groups (APL at diagnosis, at remission and healthy controls) were analyzed in two-way comparisons. The functional categories of differentially methylated genes were determined using the Ingenuity Pathway Analysis (IPA, Ingenuity Systems). After filtering, 2,996 out of 27,578 features from the platform were selected. One hundred and eighteen hypermethylated loci were exclusively found in APL at diagnosis, and 72 were commonly found in healthy subjects and patients in remission, pointing out the similarity between the 2 groups. Clustering based on the filtered set of features showed distinct methylation patterns for three of the four samples at diagnosis, and for two of the samples of APL at remission and three in healthy samples. The genes found hypermethylated at diagnosis were mainly associated with cell death regulation (IPA score=31) and cancer development (IPA score=13). In order to correlate methylation and gene expression profiles, the number of transcripts of 214 genes was analyzed by real time PCR using three platforms of PCR Array (SABioscience-Qiagen). We analyzed the methylation status and gene expression of 20 genes detected hypermethylated in APL at diagnosis, of which nine were downregulated (EGF, ERBB2, FHIT, IL1A, JAK2, MLH1, MMP-7, TERT and WNT2) and two upregulated (RARA and WT1) when compared to samples of healthy controls (Table). The analysis of WT1 expression is of special relevance because it has been used for minimal residual disease detection in APL. Our results suggest that the aberrant expression of WT1 is not dependent on the epigenetic control by PML/RARa. Among the genes founded hypermethylated and downregulated, TERT, that encodes the catalytic subunit of telomerase and which transcription seems to be repressed in differentiating cells, has been demonstrated to be regulated by WT1. This is not the reflection of differentiation, since only CD117+ cells were analyzed. We also analyzed the expression of six genes detected hypermethylated in samples of healthy controls, of interest BRCA2 and HGF genes were hypermethylated but their expression was down and upregulated, respectively. Aberrant expression HGF is frequent in AML and leads to the autocrine activation of its receptor tyrosine kinase, MET, which promotes cell growth and survival of HGF-expressing AML cells. In conclusion, our results provide a first glimpse of the variation in DNA methylation among samples from APL patients at diagnosis and at remission compared to healthy controls, and identified potential target genes capable of conferring survival advantage to the leukemic cell. Table. Correlation between gene methylation and expression in APL at diagnosis (D), remission (R) and in healthy controls (HC) Gene Symbol Methylated Group Expression (Fold Change) D × HC p value BCL2 HC/R NS BRCA2 HC −3.2 0.02 CD5 D NS CDH1 D NS CDKN1C D NS CDKN2B D NS EGF D −12.66 0.04 ERBB2 D −2.15 0.001 FHIT D −6.43 0.02 GREB1 HC NS HGF HC 21.53 0.04 IL1A D −11.03 0.04 JAK2 D −2.55 0.03 LEP D NS MET D NS MLH1 D −3.52 0.001 MMP-7 D −6.43 0.01 FN1 HC NS NF1A D NS RARA D 3.72 0.002 SFN D NS TERT D −12.38 0.03 TESC D NS TNF HC/R NS WNT2 D −7.32 0.03 WT1 D 111.52 0.05 HC, Healthy Controls; R, Remission; D, Diagnosis; NS, not significant. Disclosures: No relevant conflicts of interest to declare.