Copy Number Variation Analysis Research Articles

Early Hints of Metagenome Next‐Generation Sequencing and Copy Number Variations Analysis: An Occult Case of Leptomeningeal Metastasis With Rapid Cognitive Decline

ABSTRACTEarly detection and treatment are critical for improving the prognosis of patients with leptomeningeal metastasis. However, heterogeneous clinical manifestations, non‐specific imaging, and limited sensitivity of cerebrospinal fluid cytology posed challenges to identifying leptomeningeal metastasis in the early stage. Here we reported a case of lung adenocarcinoma complaining of rapid cognitive decline, whose magnetic resonance imaging showed interstitial brain edema. Under the circumstances of negative cerebrospinal fluid cytology, metagenome next‐generation sequencing and copy number variations analysis were applied, which indicated leptomeningeal metastasis and was confirmed in the subsequent cytology.

MFRP, PRSS56, and MYRF account for 60.5% of a Chinese cohort with nanophthalmos.

This study aimed to present the genetic profile of a rare ocular disease nanophthalmos (NO) in a large Chinese cohort, to explore its genetic characteristics and genotype-phenotype correlations. A total of 43 unrelated pedigrees diagnosed with NO were recruited. Whole exome sequencing and copy number variation analysis were performed, followed by validation and pathogenicity classification of the detected variants. The overall genetic diagnostic rate was 60.5%. Twenty-eight unique genetic variants of MFRP, PRSS56, and MYRF have been identified, of which 19 were reported for the first time. The c.1486G>A variant in MFRP and the c.1066dupC variant in PRSS56 were the two most frequent variants. Patients with variants in MFRP or PRSS56 tended to possess shorter axial lengths than those with MYRF variants. Among patients with MFRP null variants, a higher proportion developed uveal effusion syndrome (UES) than did those without null variants, whereas among patients with PRSS56 null variants, a greater number of patients developed angle-closure glaucoma (ACG). A higher proportion of MFRP-related NO patients developed both UES and ACG. MFRP, PRSS56, and MYRF account for the majority of genetic causes of NO. MFRP-related NO patients tend to exhibit a strong predisposition to complications. Null variants in MFRP and PRSS56 may increase susceptibility to clinical complications. This study provides insights into the genetic landscape and clinical characteristics of NO. These findings will lead to a better understanding of the mechanisms underlying nanophthalmos and other diseases associated with eye development.

Genetic neonatal seizures in the neonatal intensive care unit: Diagnostic and prognostic implications for three families.

We investigated neonatal seizures in three probands admitted to the neonatal intensive care units and their affected family members. Whole exome sequencing (WES) was performed along with confirmation by Sanger sequencing and segregation analysis. Copy number variant (CNV) analysis was also conducted. Neuroimaging, electroencephalography, and metabolic analysis revealed clinical phenotypes. Bi-allelic variants c.1025T>C and c.1150G>A in MOCS1 were found in twin girls with molybdenum cofactor deficiency. The c.1025T>C variant was novel. A c.877C>T variant in KCNQ2 co-segregated with seizures in a family. A de novo 6.25 Mb duplication on 2q24.3 encompassing SCN1A, SCN2A, and SCN3A was identified in a proband who demonstrated normal development without seizures on follow-up. WES facilitated the molecular diagnosis of neonatal seizures in the study participants. Variants in the KCNQ2 and MOCS1 genes were classified as likely pathogenic based on our findings. The individual with a duplication of the sodium channel gene cluster on 2q24.3 exhibited additional phenotypes. Our investigation expanded the genotype-phenotype spectrum.

Rare copy number variant analysis in case–control studies using snp array data: a scalable and automated data analysis pipeline

BackgroundRare copy number variants (CNVs) significantly influence the human genome and may contribute to disease susceptibility. High-throughput SNP genotyping platforms provide data that can be used for CNV detection, but it requires the complex pipelining of bioinformatic tools. Here, we propose a flexible bioinformatic pipeline for rare CNV analysis from human SNP array data.ResultsThe pipeline consists of two major sub-pipelines: (1) Calling and quality control (QC) analysis, and (2) Rare CNV analysis. It is implemented in Snakemake following a rule-based structure that enables automation and scalability while maintaining flexibility.ConclusionsOur pipeline automates the detection and analysis of rare CNVs. It implements a rigorous CNV quality control, assesses the frequencies of these rare CNVs in patients versus controls, and evaluates the impact of CNVs on specific genes or pathways. We hence aim to provide an efficient yet flexible bioinformatic framework to investigate rare CNVs in biomedical research.

EPCO-23. LONGITUDINAL TRACKING AND LONG-READ CHROMATIN FIBER SEQUENCING OF HUMAN ASTROCYTES WITH TELOMERE DYSFUNCTION REVEALED ALTERED CHROMATIN ACCESSIBILITY AND INCREASED STRUCTURAL VARIATION

Abstract Glioma is an aggressive cancer of the central nervous system that is genetically characterized by aneuploidy and frequent structural variation (SV). We sought to investigate the role of telomere dysfunction (TD) in shaping the SV landscape in glioma. Normal human astrocytes (NHA) were engineered to express viral E6E7 oncoproteins which are known to spontaneously trigger TD by suppressing p53/pRb. We hypothesized that NHA-E6E7 cells gradually accumulate SVs and aneuploidy over time because of progressive TD. We therefore longitudinally tracked bulk and single-cell clones of NHA-E6E7 cells for a period of over 6 months since viral infection. Overall, NHA-E6E7 cells demonstrate a growth benefit over primary NHA cells. We obtained Illumina short-read sequencing for NHA-E6E7 cells at multiple time points. Three time points were additionally selected for both Oxford Nanopore and PacBio HiFi long-read sequencing using the single-molecule chromatin fiber sequencing (fiber-seq) protocol. Copy number variation (CNV) analysis of short-read data showed deletion events in chromosome 13 as early as population doubling level (PDL) 48. K-mer based CNV analysis using the long-read data confirmed this finding and also detected deletion events in chromosome 7 at PDL 50. From the long-read data, we found an elevated number of SVs in NHA-E6E7 cells compared to the primary NHA cells. In particular, we detected telomere junctions and found that telomere-associated SVs were more prevalent in NHA-E6E7 cells compared to primary cells. Next, chromatin accessibility and regulatory elements were predicted from fiber-seq data with exogenous N6-methyladenosine (m6A) stencils. We observed large-scale chromatin actuation changes in various regulatory elements across the genome that intensified in later passages of NHA-E6E7 cells. For example, we found a decrease in the accessibility in FBXO7 which is a gene that maintains chromosome stability. Our preliminary results indicated that TD is an important mediator of structural variation in glioma.

QLTI-06. NEXT GENERATION SEQUENCING SIGNIFICANTLY IMPROVES THE DIAGNOSTIC ACCURACY IN GLIOBLASTOMAS

Abstract The 2021 WHO Classification of CNS Tumours recognizes the presence of TERT promoter (pTERT) mutations, combined +7/-10 chromosome copy-number alterations, or EGFR amplification as a defining molecular feature(s) of glioblastoma, independent of histology. We evaluated these biomarkers in a cohort of Indian patients using a single-run next-generation sequencing (NGS) platform at a relatively low depth of 100. Seventy-four adult diffuse gliomas were selected from the Exsegen Genomics Research Pvt Ltd Biobank established during the trial CTRI/2021/09/036861 after reviewing their clinical and pathological data. Paired surgical tissue and blood samples underwent whole-exome sequencing on an Illumina NovaSeq-6000 (Illumina, San Diego, USA). Single-nucleotide variations (SNVs) were processed using the DRAGEN pipeline to generate Mutation Annotation Format (MAF) files. Copy number variations (CNVs) analysis was performed using GATK and GISTIC2.0. Thirty-nine glioma samples with IDH1R132H mutations were excluded. A total of 32/35 (91.4%) IDH-wildtype tumours met the 2021 WHO criteria for glioblastoma, IDH-wildtype and were included. Twenty-four glioblastomas also underwent whole-transcriptome analysis. Microvascular proliferation (n=24, 75%) and necrosis (n=30, 93.9%) were present in the majority. pTERT mutations were identified in 23 (71.9%) samples, with C228T mutations (n=15/23, 65.2%) being more common than C250T mutations (n=8/23, 34.8%). EGFR amplification, defined as ≥5 copies by NGS CNV, was seen in 15 (46.9%) samples, with a strong correlation between EGFR CNV and logEGFR expression (r=0.79; p=0.017). Whole-arm +7/-10 genotype was evident in 17 (53.1%) tumours, and another 5 (15.6%) showed partial copy-number alterations. Notably, two gliomas without necrosis and proliferation initially diagnosed as oligodendrogliomas due to misinterpretation of the IDH immunostain, were reclassified as glioblastoma, IDH-wildtype. The data was validated using Sanger Sequencing and targeted panel sequencing to a depth of 500. Even low depth NGS sequencing, that is cost effective and time efficient offers significant improvements in diagnostic molecular neuropathology.

Insights into Adaption and Growth Evolution: Genome-Wide Copy Number Variation Analysis in Chinese Hainan Yellow Cattle Using Whole-Genome Re-Sequencing Data.

Copy number variation (CNV) serves as a crucial source of genomic variation and significantly aids in the mining of genomic information in cattle. This study aims to analyze re-sequencing data from Chinese Hainan yellow cattle, to uncover breed CNV information, and to elucidate the resources of population genetic variation. We conducted whole-genome sequencing on 30 Chinese Hainan yellow cattle, thus generating 814.50 Gb of raw data. CNVs were called using CNVnator software, and subsequent filtering with Plink and HandyCNV yielded 197,434 high-quality CNVs and 5852 CNV regions (CNVRs). Notably, the proportion of deleted sequences (81.98%) exceeded that of duplicated sequences (18.02%), with the lengths of CNVs predominantly ranging between 20 and 500 Kb This distribution demonstrated a decrease in CNVR count with increasing fragment length. Furthermore, an analysis of the population genetic structure using CNVR databases from Chinese, Indian, and European commercial cattle breeds revealed differences between Chinese Bos indicus and Indian Bos indicus. Significant differences were also observed between Hainan yellow cattle and European commercial breeds. We conducted gene annotation for both Hainan yellow cattle and European commercial cattle, as well as for Chinese Bos indicus and Indian Bos indicus, identifying 206 genes that are expressed in both Chinese and Indian Bos indicus. These findings may provide valuable references for future research on Bos indicus. Additionally, selection signatures analysis based on Hainan yellow cattle and three European commercial cattle breeds identified putative pathways related to heat tolerance, disease resistance, fat metabolism, environmental adaptation, candidate genes associated with reproduction and the development of sperm and oocytes (CABS1, DLD, FSHR, HSD17B2, KDM2A), environmental adaptation (CNGB3, FAM161A, DIAPH3, EYA4, AAK1, ERBB4, ERC2), oxidative stress anti-inflammatory response (COMMD1, OXR1), disease resistance (CNTN5, HRH4, NAALADL2), and meat quality (EHHADH, RHOD, GFPT1, SULT1B1). This study provides a comprehensive exploration of CNVs at the molecular level in Chinese Hainan yellow cattle, offering theoretical support for future breeding and selection programs aimed at enhancing qualities of this breed.

Genome-wide detection and analysis of copy number variations in Sal sheep using a high-density SNP array

Purpose: to identify CNV regions (CNVRs) and identify potentially specific CNVs in Sal sheep.Materials and methods. The research was carried out on 48 Salsk breed sheep. Genotyping was performed using high-density microarrays Ovine SNP 600 K BeadChip array (Illumina, USA). DNA copy number variation (CNV) searches were performed using PennCNV software based on the Oar_v3.1 reference genome.Results. We identified 4585 autosomal CNVs in 48 Sal breed sheep. The average CNV length was 92,3 Kb. 21,1 % of the total number of CNVs are less than 50 Kb in size. On average, from 65 to 138 CNVs were identified per animal. 527 autosomal CNVRs were obtained, representing 54,77 Mb of the entire sheep genome. The proportion of chromosomes covered by CNVR varies by chromosome, from 0,5 % on OAR25 to 9 % on OAR24. Analysis of CNVR in the ENCEMBL system revealed 42 genes in which CNVRs are localized; the remaining CNVRs are located in intergenic regions. Comparison of the identified CNVRs with sheep QTLs from the Animal QTL database showed that 39,24 % of the genes were responsible for reproductive traits, and 20,25 % were responsible for wool-related traits.Conclusions. Functional annotation of CNVRs localized in genes and intergenic spaces was carried out and the total number of detected CNVRs in the QTL database was analyzed. The results showed that CNVs are localized in genes associated with selection-significant traits in sheep.

Germline copy number variants and endometrial cancer risk

Known risk loci for endometrial cancer explain approximately one third of familial endometrial cancer. However, the association of germline copy number variants (CNVs) with endometrial cancer risk remains relatively unknown. We conducted a genome-wide analysis of rare CNVs overlapping gene regions in 4115 endometrial cancer cases and 17,818 controls to identify functionally relevant variants associated with disease. We identified a 1.22-fold greater number of CNVs in DNA samples from cases compared to DNA samples from controls (p = 4.4 × 10–63). Under three models of putative CNV impact (deletion, duplication, and loss of function), genome-wide association studies identified 141 candidate gene loci associated (p < 0.01) with endometrial cancer risk. Pathway analysis of the candidate loci revealed an enrichment of genes involved in the 16p11.2 proximal deletion syndrome, driven by a large recurrent deletion (chr16:29,595,483-30,159,693) identified in 0.15% of endometrial cancer cases and 0.02% of control participants. Together, these data provide evidence that rare copy number variants have a role in endometrial cancer susceptibility and that the proximal 16p11.2 BP4-BP5 region contains 25 candidate risk gene(s) that warrant further analysis to better understand their role in human disease.

Identification of genetic fingerprint of type I interferon therapy in visceral metastases of melanoma

Malignant melanoma is a difficult-to-treat skin cancer with increasing incidence worldwide. Although type-I interferon (IFN) is no longer part of guidelines, several melanoma patients are treated with type-I interferon (IFN) at some point of the disease, potentially affecting its genetic progression. We run genome-wide copy number variation (CNV) analysis on previously type-I IFN-treated (n = 17) and control (n = 11) visceral metastases of melanoma patients. Results were completed with data from the TCGA and MM500 databases. We identified metastasis- and brain metastasis-specific gene signatures mostly affected by CN gains. Some cases were genetically resistant to IFN showing characteristic gene alterations (e.g. ABCA4 or ZEB2 gain and alterations of DNA repair genes). Analysis of a previously identified type-I IFN resistance gene set indicates that only a proportion of these genes was exclusive for the IFN-treated metastases reflecting a possible selective genomic pressure of endogenous IFNs during progression. Our data suggest that previous type-I IFN treatment and/or endogenous IFN production by immune response affect genomic progression of melanoma which may have clinical relevance, potentially influence immune checkpoint regulation in the tumor microenvironment.

Genomic and transcriptomic profiling of inflammatory breast cancer reveals distinct molecular characteristics to non-inflammatory breast cancers.

Inflammatory breast cancer (IBC), a rare and highly aggressive form of breast cancer, accounts for 10% of breast cancer-related deaths. Previous omics studies of IBC have focused solely on one of genomics or transcriptomics and did not discover common differences that could distinguish IBC from non-IBC. Seventeen IBC patients and five non-IBC patients as well as additional thirty-three Asian breast cancer samples from TCGA-BRCA were included for the study. We performed whole-exon sequencing (WES) to investigate different somatic genomic alterations, copy number variants, and large structural variants between IBC and non-IBC. Bulk RNA sequencing (RNA-seq) was performed to examine the differentially expressed genes, pathway enrichment, and gene fusions. WES and RNA-seq data were further investigated in combination to discover genes that were dysregulated in both genomics and transcriptomics. Copy number variation analysis identified 10 cytobands that showed higher frequency in IBC. Structural variation analysis showed more frequent deletions in IBC. Pathway enrichment and immune infiltration analysis indicated increased immune activation in IBC samples. Gene fusions including CTSC-RAB38 were found to be more common in IBC. We demonstrated more commonly dysregulated RAS pathway in IBC according to both WES and RNA-seq. Inhibitors targeting RAS signaling and its downstream pathways were predicted to possess promising effects in IBC treatment. We discovered differences unique in Asian women that could potentially explain IBC etiology and presented RAS signaling pathway as a potential therapeutic target in IBC treatment.

The molecular history of IDH-mutant astrocytomas without adjuvant treatment.

Hypermutation and malignant transformation are potential complications arising from temozolomide treatment of IDH-mutant gliomas. However, the natural history of IDH-mutant low-grade gliomas without temozolomide treatment is actually under-studied. We retrieved retrospectively from our hospitals paired tumors from 19 patients with IDH-mutant, 1p19q non-codeleted Grade 2 astrocytomas where no interim adjuvant treatment with either temozolomide or radiotherapy was given between primary resections and first recurrences. Tissues from multiple recurrences were available from two patients and radiotherapy but not temozolomide was given before the last specimens were resected. We studied the natural molecular history of these low-grade IDH-mutant astrocytomas without pressure of temozolomide with DNA methylation profiling and copy number variation (CNV) analyses, targeted DNA sequencing, TERTp sequencing, FISH for ALT and selected biomarkers. Recurrences were mostly higher grades (15/19 patients) and characterized by new CNVs not present in the primary tumors (17/19 cases). Few novel mutations were identified in recurrences. Tumors from 17/19 (89.5%) patients showed either CDKN2A homozygous deletion, MYC or PDGFRA focal and non-focal gains at recurrences. There was no case of hypermutation. Phylogenetic trees constructed for tumors for the two patients with multiple recurrences suggested a lack of subclone development in their evolution when under no pressure from temozolomide. In summary, our studies demonstrated, in contrast to the phenomenon of temozolomide-induced hypermutation, IDH-mutant, 1p19q non-codeleted Grade 2 astrocytomas which had not been treated by temozolomide, acquired new CNVs at tumor recurrences. These findings improve our understanding of the molecular life history of IDH-mutant astrocytomas.

Exploring tumor endothelial cells heterogeneity in hepatocellular carcinoma: insights from single-cell sequencing and pseudotime analysis.

This study aimed to explore the heterogeneity of tumor endothelial cells (TECs) in hepatocellular carcinoma (HCC) and their role in tumor progression, with the goal of identifying new therapeutic targets and strategies to improve patient prognosis. Single-cell RNA sequencing data from nine primary liver cancer samples were analyzed, obtained from the Gene Expression Omnibus (GEO) database. Data preprocessing, normalization, dimensionality reduction, and batch effect correction were performed based on the Seurat package. HCC cell types were identified using uniform manifold approximation and projection (UMAP) and cluster analysis, and the different cell types were annotated using the CellMarker database. Pseudotime trajectory analysis was conducted with Monocle to explore the differentiation trajectory of TECs. MAPK signaling pathway activity and copy number variations (CNV) in TECs were analyzed in conjunction with data from The Cancer Genome Atlas (TCGA), the trans-well and wound healing assay was used for cell invasion and migration activity assessment. Two subgroups of TECs (TECs 1 and TECs 2) were identified, exhibiting distinct functional activities and signaling pathways. Specifically, TECs 1 may be involved in tumor cell proliferation and inflammatory responses, whereas TECs 2 is not only involved in cell proliferation pathways, but also enriched in pathways such as metabolic synthesis. Pseudotime analysis revealed dynamic changes in TECs subgroups during HCC progression, correlating specific gene expressions (such as PDGFRB, PGF, JUN, and NR4A1). Subsequently, the JUN gene was predicted by performing binding sites and was shown to act as a transcription factor that may regulate the expression of the PGF gene. CNV analysis highlighted key genes and pathways in TECs that might influence HCC progression, and the PGF as key regulatory factor mediated cell proliferation and migration. The study revealed the heterogeneity of TECs in HCC and their potential roles in tumor progression, offering new perspectives and potential therapeutic targets for HCC molecular mechanisms. The findings emphasize the importance of further exploring TECs heterogeneity for understanding HCC pathogenesis and developing personalized treatment strategies.

A burden of rare copy number variants in obsessive-compulsive disorder.

Current genetic research on obsessive-compulsive disorder (OCD) supports contributions to risk specifically from common single nucleotide variants (SNVs), along with rare coding SNVs and small insertion-deletions (indels). The contribution to OCD risk from rare copy number variants (CNVs), however, has not been formally assessed at a similar scale. Here we describe an analysis of rare CNVs called from genotype array data in 2248 deeply phenotyped OCD cases and 3608 unaffected controls from Sweden and Norway. Cases carry an elevated burden of CNVs ≥30 kb in size (OR = 1.12, P = 1.77 × 10-3). The excess rate of these CNVs in cases versus controls was around 0.07 (95% CI 0.02-0.11, P = 2.58 × 10-3). This signal was largely driven by CNVs overlapping protein-coding regions (OR = 1.19, P = 3.08 × 10-4), particularly deletions impacting loss-of-function intolerant genes (pLI >0.995, OR = 4.12, P = 2.54 × 10-5). We did not identify any specific locus where CNV burden was associated with OCD case status at genome-wide significance, but we noted non-random recurrence of CNV deletions in cases (permutation P = 2.60 × 10-3). In cases where sufficient clinical data were available (n = 1612) we found that carriers of neurodevelopmental duplications were more likely to have comorbid autism (P < 0.001), and that carriers of deletions overlapping neurodevelopmental genes had lower treatment response (P = 0.02). The results demonstrate a contribution of rare CNVs to OCD risk, and suggest that studies of rare coding variation in OCD would have increased power to identify risk genes if this class of variation were incorporated into formal tests.

Application of Genetic Origin Analysis of Copy Number Variations in Non-Invasive Prenatal Testing.

This study aimed to assess the application of origin analysis of copy number variations (CNVs) in non-invasive prenatal testing (NIPT) and provide a basis for expanding the clinical application of NIPT. We enrolled 35,317 patients who underwent NIPT between January 2019 and March 2023. Genome sequencing of copy number variation (CNV-Seq) analysis was performed using the CNV calling pipeline to identify subchromosomal abnormalities in maternal plasma. Genetic origin was determined by comparing the chimaerism ratio of CNV and the concentration of cell-free foetal DNA (cffDNA). All pregnant women with a high risk of CNV, as indicated by the NIPT, were informed of their genetic origins. Amniocentesis was recommended for detecting the CNVs in foetal chromosomes, and pregnancy outcomes were tracked. A total of 109 pregnancies showed clinically significant positive results for CNV after NIPT, including 65 cases of maternal/foetal (M/F)-CNVs and 44 cases of F-CNVs. The occurrence of M/F-CNVs was independent of age, screening (serological or ultrasound) indications for abnormalities, and mode of pregnancy. The incidence of pathogenic/likely pathogenic (P/LP)-F-CNVs was high in cases where serological screening indicated intermediate, high-risk, or abnormal US findings (p<0.05). In the M/F-CNV group, most of the P/LP-CNVs were small fragments with low penetrance; 55 (84.62%) were less than 5Mb in size, and nine (13.85%) were between 5 and 10Mb. In the F-CNV group, foetal P/LP-CNV was detected in 36 of 42 cases undergoing prenatal diagnosis, and no significant bias was noted in the size distribution of P/LP-F-CNV fragments. The prenatal diagnostic rate and positive predictive value in the F-CNV group were 95.45% and 85.71%, respectively, which were significantly different from those in the M/F group (26.15% and 52.95%), respectively (p<0.05). Genetic origin analysis of CNV can effectively improve adherence to prenatal diagnosis in pregnant women and the accuracy of prenatal diagnosis.

Identification and Copy Number Variant Analysis of Enhancer Regions of Genes Causing Spinocerebellar Ataxia.

Currently, routine diagnostics for spinocerebellar ataxia (SCA) look for polyQ repeat expansions and conventional variations affecting the proteins encoded by known SCA genes. However, ~40% of the patients still remain without a genetic diagnosis after routine tests. Increasing evidence suggests that variations in the enhancer regions of genes involved in neurodegenerative disorders can also cause disease. Since the enhancers of SCA genes are not yet known, it remains to be determined whether variations in these regions are a cause of SCA. In this pilot project, we aimed to identify the enhancers of the SCA genes ATXN1, ATXN3, TBP and ITPR1 in the human cerebellum using 4C-seq, publicly available datasets, reciprocal 4C-seq, and luciferase assays. We then screened these enhancers for copy number variants (CNVs) in a cohort of genetically undiagnosed SCA patients. We identified two active enhancers for each of the four SCA genes. CNV analysis did not reveal any CNVs in the enhancers of the four SCA genes in the genetically undiagnosed SCA patients. However, in one patient, we noted a CNV deletion with an unknown clinical significance near one of the ITPR1 enhancers. These results not only reveal elements involved in SCA gene regulation but can also lead to the discovery of novel SCA-causing genetic variants. As enhancer variations are being increasingly recognized as a cause of brain disorders, screening the enhancers of ATXN1, ATXN3, TBP and ITPR1 for variations other than CNVs and identifying and screening enhancers of other SCA genes might elucidate the genetic cause in undiagnosed patients.

THE MOLECULAR HISTORY OF IDH-MUTANT ASTROCYTOMAS WITHOUT ADJUVANT TREATMENT

Abstract AIMS Hypermutation and malignant transformation are potential complications arising from temozolomide treatment of IDH-mutant gliomas. However, the natural history of IDH-mutant low-grade gliomas without temozolomide treatment is relatively un-studied. We set out to study the molecular history of paired IDH-mutant astrocytomas without adjuvant treatment in the interim. METHOD We retrieved retrospectively from our hospitals paired tumors from 19 patients with IDH-mutant, 1p19q noncodeleted Grade 2 astrocytomas where no interim adjuvant treatment with either temozolomide or radiotherapy was given between primary and first recurrences. Two patients had multiple resected recurrences and radiotherapy but not temozolomide was given before the last specimens were resected. We studied the natural molecular history of these low-grade IDH-mutant astrocytomas without pressure of temozolomide with methylation profiling and copy number variation (CNV) analyses, target DNA sequencing, TERTp sequencing, FISH for ALT and selected biomarkers. RESULTS Recurrences were mostly higher grades (15/19 patients) and characterized by new CNVs not present in the primary tumors (17/19 cases). Few novel mutations were identified in recurrences. Tumors from 17/19 (89.5%) patients showed either CDKN2A homozygous deletion, MYC or PDGFRA amplification at recurrences. There was no case of hypermutation. Phylogenetic trees constructed for tumors for the two patients with multiple recurrences showed a conserved evolution pattern. CONCLUSION In summary, our studies demonstrated in contrast to the phenomenon of temozolomide-induced hypermutation, IDH-mutant, 1p19q non-codeleted Grade 2 astrocytomas which were not treated by temozolomide instead acquired new CNVs at tumor recurrences. These findings improve our understanding of the molecular life history of IDH-mutant astrocytomas.

Uterine mesenchymal tumours harboring the KAT6B/A::KANSL1 gene fusion represent a distinct type of uterine sarcoma based on DNA methylation profiles

Uterine mesenchymal tumours harboring KAT6B/A::KANSL1 gene fusions typically exhibit histological and immunophenotypic overlap with endometrial stromal and smooth muscle tumours. To date it remains uncertain whether such neoplasms should be regarded as variants of smooth muscle or endometrial stromal neoplasm, or if they constitute a distinct tumour type. In this study we investigated DNA methylation patterns and copy number variations (CNVs) in a series of uterine tumours harboring KAT6B/A::KANSL1 gene fusions in comparison to other mesenchymal neoplasms of the gynecological tract. Unsupervised hierarchical clustering and t-SNE analysis of DNA methylation data (Illumina EPIC array) identified a distinct cluster for 8/13 KAT6B/A::KANSL1 tumours (herein referred to as core cluster). The other 5 tumours (herein referred to as outliers) did not assign to the core cluster but clustered near various other tumour types. CNV analysis did not identify significant alterations in the core cluster. In contrast, various alterations, including deletions at the CDKN2A/B and NF1 loci were identified in the outlier group. Analysis of the DNA methylation clusters in relation to histological features revealed that while tumours in the core KAT6B/A::KANSL1 cluster were histologically bland, outlier tumours frequently exhibited “high-grade” histologic features in the form of significant nuclear atypia, increased mitotic activity and necrosis. Three of the five patients with outlier tumours died from their disease while clinical follow-up in the remaining two patients was limited (less than 12 months). In comparison, none of the 7 out of 8 patients with tumors in the core KAT6B/A::KANSL1 sarcoma cluster, where follow-up was available, died from disease. Furthermore, only 1 out of 7 patients recurred (mean follow-up of 30 months). In conclusion, KAT6B/A::KANSL1 uterine sarcoma is a molecularly unique type of uterine tumour that should be recognized as a distinct entity. These tumors typically exhibit low-grade histologic features but are occasionally morphologically high-grade; the latter have a DNA methylation profile different from the typical low-grade neoplasms and may be associated with aggressive behaviour.

Extensive longevity and DNA virus-driven adaptation in nearctic Myotis bats.

The rich species diversity of bats encompasses extraordinary adaptations, including extreme longevity and tolerance to infectious disease. While traditional approaches using genetic screens in model organisms have uncovered some fundamental processes underlying these traits, model organisms do not possess the variation required to understand the evolution of traits with complex genetic architectures. In contrast, the advent of genomics at tree-of-life scales enables us to study the genetic interactions underlying these processes by leveraging millions of years of evolutionary trial-and-error. Here, we use the rich species diversity of the genus Myotis - one of the longest-living clades of mammals - to study the evolution of longevity-associated traits and infectious disease using functional evolutionary genomics. We generated reference genome assemblies and cell lines for 8 closely-related (~11 MYA) species of Myotis rich in phenotypic and life history diversity. Using genome-wide screens of positive selection, analysis of structural variation and copy number variation, and functional experiments in primary cell lines, we identify new patterns of adaptation in longevity, cancer resistance, and viral interactions both within Myotis and across bats. We find that the rapid evolution of lifespan in Myotis has some of the most significant variations in cancer risk across mammals, and demonstrate a unique DNA damage response in the long-lived M. lucifugus using primary cell culture models. Furthermore, we find evidence of abundant adaptation in response to DNA viruses, but not RNA viruses, in Myotis and other bats. This is in contrast to these patterns of adaptation in humans, which might contribute to the importance of bats as a reservoir of zoonotic viruses. Together, our results demonstrate the utility of leveraging natural variation to understand the genomics of traits with implications for human health and suggest important pleiotropic relationships between infectious disease tolerance and cancer resistance.

Prognostic modeling of hepatocellular carcinoma based on T-cell proliferation regulators: a bioinformatics approach.

The prognostic value and immune significance of T-cell proliferation regulators (TCRs) in hepatocellular carcinoma (HCC) have not been previously reported. This study aimed to develop a new prognostic model based on TCRs in patients with HCC. This study used The Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC) and International Cancer Genome Consortium-Liver Cancer-Riken, Japan (ICGC-LIRI-JP) datasets along with TCRs. Differentially expressed TCRs (DE-TCRs) were identified by intersecting TCRs and differentially expressed genes between HCC and non-cancerous samples. Prognostic genes were determined using Cox regression analysis and were used to construct a risk model for HCC. Kaplan-Meier survival analysis was performed to assess the difference in survival between high-risk and low-risk groups. Receiver operating characteristic curve was used to assess the validity of risk model, as well as for testing in the ICGC-LIRI-JP dataset. Additionally, independent prognostic factors were identified using multivariate Cox regression analysis and proportional hazards assumption, and they were used to construct a nomogram model. TCGA-LIHC dataset was subjected to tumor microenvironment analysis, drug sensitivity analysis, gene set variation analysis, and immune correlation analysis. The prognostic genes were analyzed using consensus clustering analysis, mutation analysis, copy number variation analysis, gene set enrichment analysis, and molecular prediction analysis. Among the 18 DE-TCRs, six genes (DCLRE1B, RAN, HOMER1, ADA, CDK1, and IL1RN) could predict the prognosis of HCC. A risk model that can accurately predict HCC prognosis was established based on these genes. An efficient nomogram model was also developed using clinical traits and risk scores. Immune-related analyses revealed that 39 immune checkpoints exhibited differential expression between the high-risk and low-risk groups. The rate of immunotherapy response was low in patients belonging to the high-risk group. Patients with HCC were further divided into cluster 1 and cluster 2 based on prognostic genes. Mutation analysis revealed that HOMER1 and CDK1 harbored missense mutations. DCLRE1B exhibited an increased copy number, whereas RAN exhibited a decreased copy number. The prognostic genes were significantly enriched in tryptophan metabolism pathways. This bioinformatics analysis identified six TCR genes associated with HCC prognosis that can serve as diagnostic markers and therapeutic targets for HCC.