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Clonal hematopoiesis (CH) is a condition in which healthy individuals have somatic mutations in hematopoietic stem cells. It has been reported with increased risk of hematologic malignancy and cardiovascular disease in the general population, but studies of Korean populations with comorbid disease entities are scarce. White blood cells (WBCs) from patients with gastric cancer (GC) (n=121) were analyzed using a DNA-based targeted (531 genes) panel with customized pipeline designed to detect single nucleotide variants and small indels with low-allele-frequency of ≥0.2 %. We defined significant CH variants as having variant allele frequency (VAF) ≥2 % among variants found in WBCs. Matched cell-free DNA (cfDNA) samples were also analyzed with the same pipeline to investigate the false-positive results caused by WBC variants in cfDNA profiling. Significant CH variants were detected in 29.8 % of patients and were associated with age and male sex. The number of CH variants was associated with a history of anti-cancer therapy and age. DNMT3A and TET2 were recurrently mutated. Overall survival rate of treatment-naïve patients with stage IV GC was higher in those with CH, but Cox regression showed no significant association after adjustment for age, sex, anti-cancer therapy, and smoking history. In addition, we analyzed the potential interference of WBC variants in plasma cell-free DNA testing, which has attracted interest as a complementary method for tissue biopsy. Results showed that 37.0 % (47/127) of plasma specimens harbored at least one WBC variant. VAFs of interfering WBC variants in the plasma and WBC were correlated, and WBC variants with VAF ≥4 % in WBC were frequently detected in plasma with the same VAF. This study revealed the clinical impact of CH in Korean patients and suggests the potential for its interference in cfDNA tests. [ABSTRACT FROM AUTHOR]

Simple Summary: Circulating tumor DNA (ctDNA) has emerged as a potential biomarker for clear cell renal cell carcinoma (ccRCC). However, the ctDNA characteristics have not been demonstrated in small ccRCC. The aim of our pilot study is to explore the characteristics of ctDNA in pT1a ccRCC (ccRCC less than 4 cm in diameter). We included 53 patients with pT1a ccRCC, a greater number than in previous studies using next-generation sequencing. We found that the ctDNA detection rate was low in pT1a ccRCC. The relationship between ctDNA and clinicopathological features, such as tumor size, tumor grade, and patient age, was not clear. Increasing the sensitivity and removing background noise in ctDNA analysis may aid in further understanding the characteristics of ctDNA, thereby enhancing its clinical utility in pT1a ccRCC. Circulating tumor DNA (ctDNA) is a promising biomarker for clear cell renal cell carcinoma (ccRCC); however, its characteristics in small renal masses of ccRCC remain unclear. In this pilot study, we explored the characteristics of ctDNA in pT1a ccRCC. Plasma samples were collected preoperatively from 53 patients with pT1a ccRCC. The ctDNA of pT1a ccRCC was profiled using next-generation sequencing and compared with that of higher-stage ccRCC. The association of ctDNA in pT1a ccRCC with clinicopathological features was investigated. The positive relationship of mutations between ctDNA and matched tissues was evaluated. In pT1a ccRCC, the ctDNA detection rate, cell-free DNA concentration, and median variant allele frequency were 20.8%, 5.8 ng/mL, and 0.38%, respectively, which were significantly lower than those in metastatic ccRCC. The ctDNA gene proportions in pT1a samples differed from those in metastatic ccRCC samples. The relationships between ctDNA and tumor size, tumor grade, and patient age were not elucidated. The positive concordance between ctDNA and matched tissues was poor for pT1a ccRCC. Strategies are needed to increase sensitivity while eliminating noise caused by clonal hematopoiesis to increase the clinical utility of ctDNA analysis in small renal masses of ccRCC. [ABSTRACT FROM AUTHOR]

Background: BCR::ABL1 fusion has significant prognostic value and is screened for chronic myeloid leukemia (CML) disease monitoring as a part of routine molecular testing. To overcome the limitations of the current standard real-time quantitative polymerase chain reaction (RQ-PCR), we designed and validated a next-generation sequencing (NGS)-based assay to quantify BCR::ABL1 and ABL1 transcript copy numbers. Methods: After PCR amplification of the target sequence, deep sequencing was performed using an Illumina Nextseq 550Dx sequencer and in-house–designed bioinformatics pipeline. The Next-generation Quantitative sequencing (NQ-seq) assay was validated for its analytical performance, including precision, linearity, and limit of detection, using serially diluted control materials. A comparison with conventional RQ-PCR was performed with 145 clinical samples from 77 patients. Results: The limit of detection of the NQ-seq was the molecular response (MR) 5.6 [BCR::ABL1 0.00028% international scale (IS)]. The NQ-seq exhibited excellent precision and linear range from MR 2.0 to 5.0. The IS value from the NQ-seq was highly correlated with conventional RQ-PCR. Conclusions: We conclude that the NQ-seq is an effective tool for monitoring BCR::ABL1 transcripts in CML patients with high sensitivity and reliability. Prospective assessment of the unselected large series is required to validate the clinical impact of this NGS-based monitoring strategy. [ABSTRACT FROM AUTHOR]

To report a case of primary vitreoretinal lymphoma (PVRL) showing recurrence after spontaneous regression, diagnosed with the aid of next-generation sequencing (NGS). Retrospective case report. A 61-year-old immunocompetent Korean woman presented with subretinal lesions suspected of PVRL, which resolved spontaneously in 2 months. After 8 months, the lesion recurred and diagnostic vitrectomy was performed. The cytologic examination of the vitreous was indeterminate as there was only minimal vitreous opacity present at the time of surgery. NGS identified significant mutations including single nucleotide variants in MYD88 L265P, which is a unique hallmark of VRL, in vitreous sample, and the diagnosis of PVRL was made. This case showed PVRL can spontaneously regress almost completely, then recur, so careful ophthalmic and systemic follow-ups are warranted. When cytological confirmation is challenging due to the minimal disease involvement in the vitreous, NGS is effective in confirming the mutation profiles of PVRL. [ABSTRACT FROM AUTHOR]

Identification of gene fusion is an essential part in the management of patients with acute leukemia, not only for diagnosis but also in predicting the treatment outcome and selecting appropriate treatment. Adopting next-generation sequencing (NGS) technology for identification of gene fusion in patients with acute leukemia can be a good alternative to conventional tests. In the present study, the NGS RNA fusion gene panel test was applied to diagnostic samples of patients with acute leukemia to identify fusion genes more efficiently. Among 134 patients with acute leukemia, 53 gene fusions were detected in 52 patients. In addition to the recurrent gene fusions specified in the WHO diagnostic criteria, 11 rare or novel gene fusions were identified. Of those, two were gene fusions associated with Philadelphia-like acute lymphoblastic leukemia (Ph-like ALL), two were novel gene fusions, three were gene fusions with novel partner genes, and six were rare gene fusions from previous reports. We confirmed the clinical utility of the NGS test in identifying clinically significant gene fusions such as gene fusions involving KMT2A that has a large number of partners. Notably, Ph-like ALL-associated gene fusions could be easily identified despite the wide variety of genes involved. The results from the present study may contribute toward a better understanding of the genomic landscape of acute leukemia as well as patient management. [ABSTRACT FROM AUTHOR]

The clinical heterogeneity of autism spectrum disorder (ASD) is closely associated with the diversity of genes related to ASD pathogenesis. With their low effect size, it has been hard to define the role of common variants of genes in ASD phenotype. In this study, we reviewed genetic results and clinical scores widely used for ASD diagnosis to investigate the role of genes in ASD phenotype considering their functions in molecular pathways. Genetic data from next-generation sequencing (NGS) were collected from 94 participants with ASD. We analyzed enrichment of cellular processes and gene ontology using the Database for Annotation, Visualization, and Integrated Discovery (DAVID). We compared clinical characteristics according to genetic functional characteristics. We found 266 genes containing nonsense, frame shift, missense, and splice site mutations. Results from DAVID revealed significant enrichment for "ion channel" with an enrichment score of 8.84. Moreover, ASD participants carrying mutations in ion channel-related genes showed higher total IQ (p = 0.013) and lower repetitive, restricted behavior (RRB)-related scores (p = 0.003) and mannerism subscale of social responsiveness scale scores, compared to other participants. Individuals with variants in ion channel genes showed lower RRB scores, suggesting that ion channel genes might be relatively less associated with RRB pathogenesis. These results contribute to understanding of the role of common variants in ASD and could be important in the development of precision medicine of ASD. [ABSTRACT FROM AUTHOR]

Genetic diagnosis of patients with neurodevelopmental disorders is imperative and a standard clinical practice. Considering the continuous accumulation of data on disease-causing variants, reanalysis of previously established sequencing data is important. Periodic reanalysis of variants with uncertain significance has become mandatory in clinical laboratories. Therefore, to confirm the utility of the reanalysis of targeted gene panel data in clinical laboratories, we re-evaluated the data of two groups of patients who had undergone targeted gene panel testing for neurodevelopmental disorders (n = 116) and epileptic encephalopathy (n = 384). This reanalysis was based on a reannotation process reflecting updated databases. Six (5.2%) and seven (1.8%) new pathogenic or likely pathogenic variants were identified in these two groups, respectively, attributable to the updated guidelines and de novo reports from unrelated patients. Although relatively low, considerable increase in the diagnostic yield was confirmed. We suggest that reanalysis of genetic variants, mainly using changes in databases and updated interpretations, should be implemented as a routine practice in clinical laboratories. [ABSTRACT FROM AUTHOR]

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impairments in social communication and restricted and repetitive behaviors and interests. Identifying the genetic background may be one of the key features for the future diagnosis and treatment of ASD. With the tremendous development in genetic diagnosis techniques, next-generation sequencing (NGS) can be used to analyze multiple genes simultaneously with a single test in laboratory and clinical settings and is well suited for investigating autism genetics. According to previous studies, there are two types of genetic variants in ASD, rare variants and common variants, and both are important in explaining pathogenesis. In this study, NGS data from 137 participants with ASD were reviewed retrospectively with consideration for comorbid epilepsy. Diagnostic yield was 17.51% (24/137), and pathogenic/likely pathogenic variants were seen more frequently in female participants. Fourteen participants were diagnosed with comorbid epilepsy, six of them had pathogenic/likely pathogenic variants (43%). Genes with variants of unknown significance (VOUS) which have one or more evidence of pathogenicity following the American College of Medical Genetics (ACMG) criteria were also reviewed in both ASD and ASD with comorbid epilepsy groups. We found that most frequently found VOUS genes have previously been reported as genes related to ASD or other developmental disorders. These results suggest that when interpreting the NGS results in the clinical setting, careful observation of VOUS with some pathological evidence might contribute to the discovery of genetic pathogenesis of neurodevelopmental disorders such as ASD and epilepsy. [ABSTRACT FROM AUTHOR]

Acute lymphoblastic leukemia (ALL) is a genetically complex and heterogeneous disease for which a wide range of genetic variations has been identified. With the need for comprehensive high-throughput analysis, we have designed a comprehensive next-generation sequencing (NGS) assay to detect somatic mutations, translocations, and copy number changes and have evaluated its clinical utility in patients with ALL. The panel reliably detected single nucleotide variations (SNV) and copy number variations (CNV) analysis was exceptionally useful in identifying genic and chromosomal CNV which dominated the genetic abnormalities of ALL. We detected SNVs and CNVs simultaneously in a single assay, which could provide an alternative or supplement for several conventional tests and simplify the testing processes. We applied the genetic information obtained to the risk stratification of patients with high risk mutations and further confirmed the clinical utility of the comprehensive genetic testing with intensive bioinformatics analysis. [ABSTRACT FROM AUTHOR]

The 2016 World Health Organization classification introduced a number of genes with somatic mutations and a category for germline predisposition syndromes in myeloid neoplasms. We have designed a comprehensive next-generation sequencing assay to detect somatic mutations, translocations, and germline mutations in a single assay and have evaluated its clinical utility in patients with myeloid neoplasms. Extensive and specified bioinformatics analyses were undertaken to detect single nucleotide variations, FLT3 internal tandem duplication, genic copy number variations, and chromosomal copy number variations. This enabled us to maximize the clinical utility of the assay, and we concluded that, as a single assay, it can be a good supplement for many conventional tests, including Sanger sequencing, RT-PCR, and cytogenetics. Of note, we found that 8.4–11.6% of patients with acute myeloid leukemia and 12.9% of patients with myeloproliferative neoplasms had germline mutations, and most were heterozygous carriers for autosomal recessive marrow failure syndromes. These patients often did not respond to standard chemotherapy, suggesting that germline predisposition may have distinct and significant clinical implications. [ABSTRACT FROM AUTHOR]

Background: We intended to evaluate diagnostic utility of a targeted gene sequencing by using next generation sequencing (NGS) panel in patients with intractable early-onset epilepsy (EOE) and find the efficient analytical step for increasing the diagnosis rate. Methods: We assessed 74 patients with EOE whose seizures started before 3 years of age using a customized NGS panel that included 172 genes. Single nucleotide variants (SNVs) and exonic and chromosomal copy number variations (CNVs) were intensively examined with our customized pipeline and crosschecked with commercial or pre-built software. Variants were filtered and prioritized by in-depth clinical review, and finally classified according to the American College of Medical Genetics and Genomics guidelines. Each case was further discussed in a monthly consensus meeting that included the participation of all laboratory personnel, bioinformaticians, geneticists, and clinicians. Results: The NGS panel identified 28 patients (37.8%) with genetic abnormalities; 25 patients had pathogenic or likely pathogenic SNVs in 17 genes including SXTBP1 (n = 3), CDKL5 (n = 2), KCNQ2 (n = 2), SCN1A (n = 2), SYNGAP1 (n = 2), GNAO1 (n = 2), KCNT1 (n = 2), BRAT1, WWOX, ZEB2, CHD2, PRICKLE2, COL4A1, DNM1, SCN8A, MECP2, SLC9A6 (n = 1). The other 3 patients had pathogenic CNVs (2 duplications and 1 deletion) with varying sizes (from 2.5 Mb to 12 Mb). The overall diagnostic yield was 37.8% after following our step-by-step approach for clinical consensus. Conclusions: NGS is a useful diagnostic tool with great utility for patients with EOE. Diagnostic yields can be maximized with a standardized and team-based approach. [ABSTRACT FROM AUTHOR]

In this study, we investigated medically or surgically actionable genes in inherited eye disease, based on clinical phenotype and genomic data. This retrospective consecutive case series included 149 patients with inherited eye diseases, seen by a single pediatric ophthalmologist, who underwent genetic testing between 1 March 2017 and 28 February 2018. Variants were detected using a target enrichment panel of 429 genes and known deep intronic variants associated with inherited eye disease. Among 149 patients, 38 (25.5%) had a family history, and this cohort includes heterogeneous phenotype including anterior segment dysgenesis, congenital cataract, infantile nystagmus syndrome, optic atrophy, and retinal dystrophy. Overall, 90 patients (60.4%) received a definite molecular diagnosis. Overall, NGS-guided precision care was provided to 8 patients (5.4%). The precision care included cryotherapy to prevent retinal detachment in COL2A1 Stickler syndrome, osteoporosis management in patients with LRP5-associated familial exudative vitreoretinopathy, and avoidance of unnecessary phlebotomy in hyperferritinemia-cataract syndrome. A revision of the initial clinical diagnosis was made in 22 patients (14.8%). Unexpected multi-gene deletions and dual diagnosis were noted in 4 patients (2.7%). We found that precision medical or surgical managements were provided for 8 of 149 patients (5.4%), and multiple locus variants were found in 2.7% of cases. These findings are important because individualized management of inherited eye diseases can be achieved through genetic testing. [ABSTRACT FROM AUTHOR]

• A CytoScan XON assay was developed to assess exon-level CNVs. • The assay detected 15 out of 23 small exon-level CNVs identified by NGS. • Three of the undetected exon level CNVs were false positives in the NGS results. • The assay could not detect the three exon-level CNVs in PKD1 and TSC2. • The assay is a promising complementary tool for the detection of exon-level CNVs. Next-generation sequencing (NGS)-based copy number variants (CNVs) have high false-positive rates. The fewer the exons involved, the higher the false-positive rate. A CytoScan XON assay was developed to assess exon-level CNVs. Twenty-three clinically relevant exon-level CNVs in 20 patient blood samples found in previous NGS studies were compared with the results from the CytoScan XON and multiplex ligation-dependent probe amplification (MLPA). Fifteen of the 23 exon-level CNVs were consistent with the NGS results. Among these, eight were confirmed using MLPA. In six out of eight discrepancies between the CytoScan Xon and NGS, MLPA was performed, and three were negative, indicating that the CNVs in NGS were false positives. The CytoScan XON exhibits a sensitivity of 72.7% for small exon-level CNVs, along with a specificity of 100%. The assay could not detect the three exon-level CNVs in PKD1 and TSC2 that were detected using both NGS and MLPA. This could be due to the distribution of the probes in some areas, and the CNV-calling regions containing multiple exons. The CytoScan XON assay is a promising complementary tool for the detection of exon-level CNVs, provided that the users carefully examine the distribution of probes and calling regions. [ABSTRACT FROM AUTHOR]

Objective We performed targeted gene-panel sequencing for children with developmental and epileptic encephalopathy (DEE) and evaluated the clinical implications of genotype–phenotype correlations. Methods We assessed 278 children with DEE using a customized gene panel that included 172 genes, and extensively reviewed their clinical characteristics, including therapeutic efficacy, according to genotype. Results In 103 (37.1%) of the 278 patients with DEE, 35 different disease-causing monogenic mutations were identified. The diagnostic yield was higher among patients who were younger at seizure onset, especially those whose seizures started during the neonatal period, and in patients with drug-resistant epilepsy. According to epilepsy syndromes, the diagnostic yield was the highest among patients with West syndrome (WS) with a history of neonatal seizures and mutations in KCNQ2 and STXBP1 were most frequently identified. On the basis of genotypes, we evaluated the clinical progression and seizure outcomes with specific therapeutic regimens; these were similar to those reported previously. In particular, sodium channel blockers were effective in patients with mutations in KCNQ2 and SCN2A in infancy, as well as SCN8A , and interestingly, the ketogenic diet also showed diverse efficacy for patients with SCN1A , CDKL5 , KCNQ2 , STXBP1, and SCN2A mutations. Unfortunately, quinidine was not effective in 2 patients with migrating focal epilepsy in infancy related to KCNT1 mutations. Conclusion Targeted gene-panel sequencing is a useful diagnostic tool for DEE in children, and genotype–phenotype correlations are helpful in anticipating the clinical progression and treatment efficacy among these patients. [ABSTRACT FROM AUTHOR]