Deletion Copy Number Variants Research Articles

Overlapping pathogenic de novo CNVs in neurodevelopmental disorders and congenital anomalies impacting constraint genes regulating early development.

Neurodevelopmental disorders (NDDs) and congenital anomalies (CAs) are rare disorders with complex etiology. In this study, we investigated the less understood genomic overlap of copy number variants (CNVs) in two large cohorts of NDD and CA patients to identify de novo CNVs and candidate genes associated with both phenotypes. We analyzed clinical microarray CNV data from 10,620 NDD and 3176 CA cases annotated using Horizon platform of GenomeArc Analytics and applied rigorous downstream analysis to evaluate overlapping genes from NDD and CA CNVs. Out of 13,796 patients, only 195 cases contained 218 validated de novo CNVs. Eighteen percent (31/170) de novo CNVs in NDD cases and 40% (19/48) de novo CNVs in CA cases contained genomic overlaps impacting developmentally constraint genes. Seventy-nine constraint genes (10.1% non-OMIM entries) were found to have significantly enriched genomic overlap within rare de novo pathogenic deletions (P value = 0.01, OR = 1.58) and 45 constraint genes (13.3% non-OMIM entries) within rare de novo pathogenic duplications (P value = 0.01, OR = 1.97). Analysis of spatiotemporal transcriptome demonstrated both pathogenic deletion and duplication genes to be highly expressed during the prenatal stage in human developmental brain (P value = 4.95 X 10-6). From the list of overlapping genes, EHMT1, an interesting known NDD gene encompassed pathogenic deletion CNVs from both NDD and CA patients, whereas FAM189A1, and FSTL5 are new candidate genes from non-OMIM entries. In summary, we have identified constraint overlapping genes from CNVs (including de novo) in NDD and CA patients that have the potential to play a vital role in common disease etiology.

Novel Insights into the Etiology, Genetics, and Embryology of Hypoplastic Left Heart Syndrome.

Hypoplastic left heart syndrome (HLHS) is a relatively rare severe congenital heart defect (CHD) closely linked to other left ventricular outflow tract (LVOT) lesions including bicuspid aortic valve (BAV), one of the most common heart defects. While HLHS, BAV, and other LVOT lesions have a strong genetic underpinning, their genetic etiology remains poorly understood. Findings from a large-scale mouse mutagenesis screen showed HLHS has a multigenic etiology and is genetically heterogenous, explaining difficulties in identifying the genetic causes of HLHS. In Ohia mice, HLHS shows incomplete penetrance. Some mice exhibited small LV with normal aorta, and others a normal LV with hypoplastic aorta, indicating the LV hypoplasia is not hemodynamically driven. In Ohia mutants, HLHS was found to have a digenic modular construction, with mutation in a chromatin modifier causing the small LV phenotype and mutation in Pcdha9 causing the aorta/aortic valve hypoplasia. The Pcdha9 mutation alone can cause BAV, and in the human genome two common deletion copy number variants spanning PCDHA7-10 are associated with BAV. Hence the digenic etiology of HLHS can account for the close association of HLHS, a rare CHD, with BAV, one of the most common CHD. Functional analysis of Ohia HLHS heart tissue showed severe mitochondrial dysfunction in the small LV, while the normal size RV is also affected but milder, suggesting possible role in vulnerability of surgically palliated HLHS patients to heart failure. These findings suggest insights into the genetics of HLHS may yield new therapies for improving outcome for patients with HLHS.

Copy number variation at the 22q11.2 locus influences prevalence, severity, and psychiatric impact of sleep disturbance

BackgroundSleep disturbance is common, impairing, and may affect symptomatology in developmental neuropsychiatric disorders. Here, we take a genetics-first approach to study the complex role of sleep in psychopathology. Specifically, we examine severity of sleep disturbance in individuals with a reciprocal copy number variant (CNV) at the 22q11.2 locus and determine sleep’s effect on psychiatric symptoms. CNVs (deletion or duplication) at this locus confer some of the greatest known risks of neuropsychiatric disorders; recent studies suggest the 22q11.2 deletion negatively impacts sleep, but sleep disruption associated with 22q11.2 duplication has not been investigated.MethodsWe compared subjective sleep disturbance and its relationship to psychiatric symptoms cross-sectionally and longitudinally over 1 year in 107 22q11.2 deletion (22qDel) carriers (14.56±8.0 years; 50% male), 42 22q11.2 duplication (22qDup) carriers (16.26±13.1 years; 54.8% male), and 88 age- and sex-matched controls (14.65±7.4 years; 47.1% male). Linear mixed models were used to compare sleep disturbance, assessed via the Structured Interview for Psychosis-Risk Syndromes (SIPS), across groups. Next, CNV carriers were categorized as good or poor sleepers to investigate sleep effects on multiple neurobehavioral traits: psychosis-risk symptoms (SIPS), autism-related behaviors (Repetitive Behavior Scale (RBS) and Social Responsiveness Scale (SRS)), real-world executive function (Behavior Rating Inventory of Executive Function (BRIEF)), and emotional/behavioral problems (Child Behavior Checklist (CBCL)). Linear mixed models tested the effect of sleep category and a group-by-sleep interaction on each measure, cross-sectionally and longitudinally.Results22qDel and 22qDup carriers both reported poorer sleep than controls, but did not differ from each other. Cross-sectionally and longitudinally, poor sleepers scored higher on positive symptoms, anxious/depressed, somatic complaints, thought problems, and aggressive behavior, as well as RBS and SRS total scores. There were significant group-by-sleep interactions for positive symptoms and the majority of CBCL subdomains, in which the difference between good and poor sleepers was larger in 22qDel compared to 22qDup.ConclusionsOur findings indicate that CNVs at the 22q11.2 locus impact sleep which, in turn, influences psychopathology. Sleep disturbances can differentially impact psychopathology, depending on 22q11.2 gene dosage. Our findings serve as a starting point for exploring a genetic basis for sleep disturbance in developmental neuropsychiatric disorders.

Whole exome analysis reveals the genomic profiling related to chemo-resistance in Chinese population with limited-disease small cell lung cancer.

The mechanism of chemo-resistance in small cell lung cancer (SCLC) is unclear. This study aims to explore the resistance-related genomic profiles of residual tumors after neo-adjuvant chemotherapy (NAC) in SCLC through the whole-exome sequencing (WES). A total of 416 limited diseases (LD) SCLC patients underwent surgery were retrospectively analyzed, of which 40 patients received NAC. Then we selected 29 patients undergoing NAC (n=19) and chemotherapy naïve (CTN, n=10) to perform WES sequence with formalin-fixed paraffin-embedded samples including tumor and paired para-tumor. In total, single nucleotide variation and mutation rate were similar between NAC and CTN groups. The mutation signatures were significantly discrepant between NAC and CTN groups, as well as among patients with partial response (PR), stable disease (SD), and progressive disease. There were more copy number variation deletions in NAC group compared with CTN group. The inactivation of TP53 and RB1 were the most significantly events in both NAC and CTN groups. RB1 nonsense mutations were recurrent in NAC group (9/19 vs. 0/9, 47.4% vs. 0%) with favorable survival, while the frame-shift deletions were frequent in CTN group (3/9 vs. 3/19, 33.3% vs.15.8%). Integrated function enrichment revealed that the frequently mutant genes were involved in cell cycle, metabolic reprogramming, and oncogenic signaling pathways in NAC group, such as BTG2 pathway, glycolysis in senescence and P53 pathway. A total of 27 genes presented frequently mutant in NAC group and might played a positive role in drug resistance. Multiple genes including BRINP3, MYH6, ST18, and PCHD15, which were associated with prognosis, occurred mutant frequently in PR and SD groups. Residual tumors after neo-adjuvant therapy exhibited different mutation signature spectrum. Multiple genes including RB1 nonsense mutations, BRINP3, MYH6, ST18, and PCHD15 were with frequent mutation in residual tumors, which might participate chemo-resistance and influenced the prognosis in patients with limited disease SCLC.

Abstract 1452: Analyses of whole exome sequencing (WES) data of hereditary lung cancer families identify germline copy number variations (CNVs) in multiple genes

Abstract Lung cancer (LC) is the most common cause of cancer mortality and the third most common cancer by incidence in the United States. While environmental factors play an important role in its development, LC risk also exhibits a high degree of heritability. Linkage analyses and genome-wide association studies have identified multiple loci associated with increased LC risk; however, much of the heritability has yet to be explained by these loci. Structural mutations, including copy number variations (CNVs), contribute to phenotypic diversity through dosage and/or cis-regulatory effects. Unbiased CNV mapping is only possible with the use of high-depth, short-read sequencing and remains much more complicated and prone to false positives than SNP detection. As the tools necessary for CNV detection have improved, both somatic and germline CNVs have been shown to play an important role in disease, especially cancer, and often they account for a significant proportion of pathogenic variants. Little has been done to understand the role of germline CNVs in the biological pathways of hereditary lung cancer (HLC). The goal of the current project is to utilize the whole exome sequencing (WES) data in identifying the CNVs in the HLC families (≥3 LC/family) recruited by the Genetic Epidemiology of Lung Cancer Consortium (GELCC). This work uses germline WES data from 203 individuals (60 with a LC diagnosis) from 25 HLC families (≥3 LC affected/family). We limited our investigation to CNVs called by two independent tools using read depth to infer copy number changes and genomic breakpoints: GATK 4 (https://gatk.broadinstitute.org) and XHMM (https://atgu.mgh.harvard.edu/xhmm/). We have identified CNVs (deletions) in the following protein coding genes: KIR2DL1 (19q13.42; OR=1.77), DMBT1 (10q26.13; OR=1.56), SIBPB1 (20p13; OR=1.53), LILRA6 (20p13; OR=1.53), and HLA-DRB5 (6p21.32; OR=1.64) in ≥3 families in at least two individuals/family. All of these genes with the exception of HLA-DRB5 were previously reported in LC studies; HLA-DRB5 was reported in other cancer studies. DMBT1 was reported to be a candidate tumor suppressor gene and frequent loss of heterozygosity (LOH) was observed in several human tumors. It is highly expressed in lung and loss of expression was reported in LC cell lines. All CNVs identified in our study are consistent with Mendelian expectations and appear to be uncommon in the general population. CNVs in these genes may contribute to the lung cancer risk in the HLC families. Further validation of the identified variants is ongoing. We will consider overall CNV burden and disease association with identified deletions and duplications. The enrichment of rare variants in oncogenically associated genes that co-segregate with LC provides specific mutations for future work and improves our understanding of the inheritance and pathogenesis of LC. Citation Format: John Waldron, Kirsten W. Termine, Anthony M. Musolf, Mariza de Andrade, Colette Gaba, Ramaswamy Govindan, Ping Yang, Ming You, Ellen Jaeger, Angelle F. Bencaz, Marshall W. Anderson, Ann G. Schwartz, Susan M. Pinney, Christopher I. Amos, Joan E. Bailey-Wilson, Diptasri M. Mandal. Analyses of whole exome sequencing (WES) data of hereditary lung cancer families identify germline copy number variations (CNVs) in multiple genes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1452.

The Use of Next-generation Sequencing in the Diagnosis of Rare Inherited Anaemias: A Joint BSH/EHA Good Practice Paper.

The Use of Next-generation Sequencing in the Diagnosis of Rare Inherited Anaemias: A Joint BSH/EHA Good Practice Paper.

Adaptation of ACMG-ClinGen Technical Standards for Copy Number Variant Interpretation Concordance.

This study aimed to evaluate inter-laboratory classification concordance for copy number variants (CNVs) with a semiquantitative point-based scoring metric recommended by the American College of Medical Genetics and Genomics (ACMG) and Clinical Genome Resources (ClinGen). A total of 234 CNVs distributed by the National Center of Clinical Laboratories (NCCLs), and 72 CNVs submitted by different laboratories, were distributed to nine clinical laboratories performing routine clinical CNV testing in China and independently classified across laboratories. The overall inter-laboratory complete classification concordance rate of the 234 distributed CNVs increased from 18% (41/234) to 76% (177/234) using the scoring metric compared to the laboratory's previous method. The overall inter-laboratory complete classification concordance rate of the 72 submitted CNVs was 65% (47/72) using the scoring metrics. The 82 variants that initially did not reach complete concordance classification and 1 additional CNV deletion were reviewed; 34 reached complete agreement, and the overall post-review complete concordance rate was 85% (260/306). Additionally, the overall percentage of classification discordance possibly impacting medical management [i.e., pathogenic (P) or likely pathogenic (LP) vs. variant of uncertain significance (VUS)] was 11% (35/306). The causes of initial and final discordance in the classification were identified. The ACMG-ClinGen framework has promoted consistency in interpreting the clinical significance of CNVs. Continuous training among laboratories, further criteria and additional clarification of the standards, sharing classifications and supporting evidence through public database, and ongoing work for dosage sensitive genes/regions curation will be beneficial for harmonization of CNVs classification.

What the New Definition of Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD) Left Behind: Genetically Acquired Fatty Liver Disease (GAFLD).

What the New Definition of Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD) Left Behind: Genetically Acquired Fatty Liver Disease (GAFLD).

Chromosomal Microarray in Children With Developmental Delay: The Experience of a Tertiary Center in Korea.

Background and Objectives: Chromosomal microarray (CMA) is a first-tier genetic test for children with developmental delay (DD), intellectual disability (ID), autism spectrum disorders (ASDs), and multiple congenital anomalies (MCA). In this study, we report our experiences with the use of CMA in Korean children with unexplained DD/ID.Methods: We performed CMA in a cohort of 308 children with DD/ID between January 2010 and September 2020. We also retrospectively reviewed their medical records. The Affymetrix CytoScan 750 K array with an average resolution of 100 kb was used to perform CMA.Results: Comorbid neurodevelopmental disorders were ASD (37 patients; 12.0%), epilepsy (34 patients; 11.0%), and attention deficit hyperactivity disorders (12 patients; 3.9%). The diagnostic yield was 18.5%. Among the 221 copy number variants (CNVs) identified, 70 CNVs (57 patients; 18.5%) were pathogenic. Deletion CNVs were more common among pathogenic CNVs (PCNVs) than in non-PCNVs (P < 0.001). The size difference between PCNVs and non-PCNVs was not significant (P = 0.023). The number of included genes within CNV intervals was significantly higher in PCNVs (average 8.6; 0–347) than in non-PCNVs (average 47.5; 1–386) (P < 0.001). Short stature and hearing difficulty were also more common in the PCNV group than in the non-PCNV group (P = 0.010 and 0.070, respectively).Conclusion: This study provides additional evidence for the usefulness of CMA in genetic testing of children with DD/ID in Korea. The pathogenicity of CNVs correlated with the number of included genes within the CNV interval and deletion type of the CNVs, but not with CNV size.

Common deletion variants causing protocadherin-α deficiency contribute to the complex genetics of BAV and left-sided congenital heart disease.

SummaryBicuspid aortic valve (BAV) with ~1%–2% prevalence is the most common congenital heart defect (CHD). It frequently results in valve disease and aorta dilation and is a major cause of adult cardiac surgery. BAV is genetically linked to rare left-heart obstructions (left ventricular outflow tract obstructions [LVOTOs]), including hypoplastic left heart syndrome (HLHS) and coarctation of the aorta (CoA). Mouse and human studies indicate LVOTO is genetically heterogeneous with a complex genetic etiology. Homozygous mutation in the Pcdha protocadherin gene cluster in mice can cause BAV, and also HLHS and other LVOTO phenotypes when accompanied by a second mutation. Here we show two common deletion copy number variants (delCNVs) within the PCDHA gene cluster are associated with LVOTO. Analysis of 1,218 white individuals with LVOTO versus 463 disease-free local control individuals yielded odds ratios (ORs) at 1.47 (95% confidence interval [CI], 1.13–1.92; p = 4.2 × 10−3) for LVOTO, 1.47 (95% CI, 1.10–1.97; p = 0.01) for BAV, 6.13 (95% CI, 2.75–13.7; p = 9.7 × 10−6) for CoA, and 1.49 (95% CI, 1.07–2.08; p = 0.019) for HLHS. Increased OR was observed for all LVOTO phenotypes in homozygous or compound heterozygous PCDHA delCNV genotype comparison versus wild type. Analysis of an independent white cohort (381 affected individuals, 1,352 control individuals) replicated the PCDHA delCNV association with LVOTO. Generalizability of these findings is suggested by similar observations in Black and Chinese individuals with LVOTO. Analysis of Pcdha mutant mice showed reduced PCDHA expression at regions of cell-cell contact in aortic smooth muscle and cushion mesenchyme, suggesting potential mechanisms for BAV pathogenesis and aortopathy. Together, these findings indicate common variants causing PCDHA deficiency play a significant role in the genetic etiology of common and rare LVOTO-CHD.

Using induced pluripotent stem cells to investigate human neuronal phenotypes in 1q21.1 deletion and duplication syndrome

Copy Number Variation (CNV) at the 1q21.1 locus is associated with a range of neurodevelopmental and psychiatric disorders in humans, including abnormalities in head size and motor deficits. Yet, the functional consequences of these CNVs (both deletion and duplication) on neuronal development remain unknown. To determine the impact of CNV at the 1q21.1 locus on neuronal development, we generated induced pluripotent stem cells from individuals harbouring 1q21.1 deletion or duplication and differentiated them into functional cortical neurons. We show that neurons with 1q21.1 deletion or duplication display reciprocal phenotype with respect to proliferation, differentiation potential, neuronal maturation, synaptic density and functional activity. Deletion of the 1q21.1 locus was also associated with an increased expression of lower cortical layer markers. This difference was conserved in the mouse model of 1q21.1 deletion, which displayed altered corticogenesis. Importantly, we show that neurons with 1q21.1 deletion and duplication are associated with differential expression of calcium channels and demonstrate that physiological deficits in neurons with 1q21.1 deletion or duplication can be pharmacologically modulated by targeting Ca2+ channel activity. These findings provide biological insight into the neuropathological mechanism underlying 1q21.1 associated brain disorder and indicate a potential target for therapeutic interventions.

CYFIP1 Dosages Exhibit Divergent Behavioral Impact via Diametric Regulation of NMDA Receptor Complex Translation in Mouse Models of Psychiatric Disorders

BackgroundGene dosage imbalance caused by copy number variations (CNVs) is a prominent contributor to brain disorders. In particular, 15q11.2 CNV duplications and deletions have been associated with autism spectrum disorder and schizophrenia, respectively. The mechanism underlying these diametric contributions remains unclear. MethodsWe established both loss-of-function and gain-of-function mouse models of Cyfip1, one of four genes within 15q11.2 CNVs. To assess the functional consequences of altered CYFIP1 levels, we performed systematic investigations on behavioral, electrophysiological, and biochemical phenotypes in both mouse models. In addition, we utilized RNA immunoprecipitation sequencing (RIP-seq) analysis to reveal molecular targets of CYFIP1 in vivo. ResultsCyfip1 loss-of-function and gain-of function mouse models exhibited distinct and shared behavioral abnormalities related to autism spectrum disorder and schizophrenia. RIP-seq analysis identified messenger RNA targets of CYFIP1 in vivo, including postsynaptic NMDA receptor (NMDAR) complex components. In addition, these mouse models showed diametric changes in levels of postsynaptic NMDAR complex components at synapses because of dysregulated protein translation, resulting in bidirectional alteration of NMDAR-mediated signaling. Importantly, pharmacological balancing of NMDAR signaling in these mouse models with diametric Cyfip1 dosages rescues behavioral abnormalities. ConclusionsCYFIP1 regulates protein translation of NMDAR and associated complex components at synapses to maintain normal synaptic functions and behaviors. Our integrated analyses provide insight into how gene dosage imbalance caused by CNVs may contribute to divergent neuropsychiatric disorders.

Abstract PO-021: Single-cell DNA sequencing as a means to directly examine the size and frequency of radiation-induced mutations - An exploratory study

Abstract This study examines if single-cell DNA sequencing may be used to study the mutational effects of ionizing radiation. As the action of ionizing radiation is a stochastic process, each cell in an irradiated sample experiences its own unique radiation-induced DNA damage. As a result, conventional sequencing methods such as bulk cell sequencing cannot be used to identify individual mutations. In this work, Epstein-Barr virus (EBV) transformed B-lymphoblastoid cells were irradiated with 6 MV X-ray radiation using a medical linear accelerator. Four samples of cells from the same population (400,000 cells/ml) were exposed to sham irradiation (0 Gray [Gy]; control), 0.5 Gy, 1.5 Gy and 3.0 Gy respectively at a common dose rate of about 600 cGy/min. Irradiated samples were incubated for 24 hrs and subsequently underwent single-cell whole-genome DNA sequencing to characterize the radiation impact. Mutational profiles of approximately 500 cells, randomly selected from each sample, were individually analyzed and compared to identify the variation of several mutational parameters as a function of dose. We quantified the copy number variations (CNV) for each cell in our samples. Additionally, we segregated insertion CNVs and deletion CNVs and independently analyzed their dose dependences. We found that the total number of CNVs (insertion and deletion combined) increased with dose, and the number of deletion CNVs consistently increased most. We have repeated the experiment and a new round of single-cell DNA sequencing is underway. If confirmed, our results will demonstrate that the mutational effects of ionizing radiation may be examined directly using single-cell sequencing. Citation Format: Felix Mathew, Jonathan Yeo, Luc Galarneau, Norma Ybarra, Patricia Tonin, Yu Chang Wang, Ioannis Ragoussis, John Kildea. Single-cell DNA sequencing as a means to directly examine the size and frequency of radiation-induced mutations - An exploratory study [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-021.

Energy Metabolism Disturbances in Cell Models of PARK2 CNV Carriers with ADHD.

The main goal of the present study was the identification of cellular phenotypes in attention-deficit-/hyperactivity disorder (ADHD) patient-derived cellular models from carriers of rare copy number variants (CNVs) in the PARK2 locus that have been previously associated with ADHD. Human-derived fibroblasts (HDF) were cultured and human-induced pluripotent stem cells (hiPSC) were reprogrammed and differentiated into dopaminergic neuronal cells (mDANs). A series of assays in baseline condition and in different stress paradigms (nutrient deprivation, carbonyl cyanide m-chlorophenyl hydrazine (CCCP)) focusing on mitochondrial function and energy metabolism (ATP production, basal oxygen consumption rates, reactive oxygen species (ROS) abundance) were performed and changes in mitochondrial network morphology evaluated. We found changes in PARK2 CNV deletion and duplication carriers with ADHD in PARK2 gene and protein expression, ATP production and basal oxygen consumption rates compared to healthy and ADHD wildtype control cell lines, partly differing between HDF and mDANs and to some extent enhanced in stress paradigms. The generation of ROS was not influenced by the genotype. Our preliminary work suggests an energy impairment in HDF and mDAN cells of PARK2 CNV deletion and duplication carriers with ADHD. The energy impairment could be associated with the role of PARK2 dysregulation in mitochondrial dynamics.

Discovery and analyses of pathogenic variants in explanted hearts from primary cardiomyopathy patients

Abstract Background Dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM) are disorders of the myocardium that affect the structure and function of the heart. Purpose The primary aim of this study was to discover damaging genetic variants in myocardial tissue from patients with DCM or HCM, who underwent heart transplantation. Methods Whole exome sequencing was performed on myocardial tissue from 103 explanted hearts with diagnosis of cardiomyopathy; 80 DCM and 13 HCM. Sanger sequencing was performed to confirm the loss-of-function variants in genes known to be linked to cardiomyopathy. RNA sequencing was conducted to confirm copy number variation deletions detected in the cohort. Burden analysis was performed by comparing the frequency of variants found in the study cohort to the frequency in the population database gnomAD. Results Rare (minor allele frequency &amp;lt;1.0E-04) loss-of-function variants, deleterious missense variants, or copy number variation deletions, collectively described as damaging variants, were identified in cardiomyopathy genes in 42 of all 93 samples (45.2%). Damaging variants were identified in 37 of 80 DCM samples (46.3%) and 5 of 13 HCM samples (38.4%). The mean read depth for normal and variant allele were comparable. All the 28 loss-of-function variants in cardiomyopathy genes found in the cardiomyopathy cases were confirmed by Sanger sequencing. Two copy number variation deletions both in titin (TTN) were also detected and confirmed. Burden analyses showed that the genes TTN and lamin A/C (LMNA) had a higher frequency of loss-of function variants in the DCM cohort (17.5% and 3.75%, respectively) compared to the reference population with genome-wide significance (p=3.45E-22 and 4.34E-07, respectively). Furthermore, our analysis showed that deleterious missense variants in osteoclast-stimulating factor 1 (OSTF1), which previously has not been associated with cardiomyopathy, was highly enriched in the DCM cohort compared to the reference population (p=2.10E-06). Conclusions The frequency of damaging variants that are likely pathogenic (46.3%) is higher in DCM cases in this cohort compared to previous studies. These data indicate that patients with end-stage DCM are more likely to have a genetic cause for their disease. As read depth of variant and normal alleles were, these are likely germline and not mosaic variants, and can enable cascade testing in family members. Moreover, our study demonstrates that CNVs in TTN that alter the reading frame can cause DCM. Funding Acknowledgement Type of funding source: None

Copy number alterations involving 59 ACMG-recommended secondary findings genes.

In clinical exome/genome sequencing, the American College of Medical Genetics and Genomics (ACMG) recommends reporting of secondary findings unrelated to a patient's phenotype when pathogenic single-nucleotide variants (SNVs) are observed in one of 59 genes associated with a life-threatening, medically actionable condition. Little is known about the incidence and sensitivity of chromosomal microarray analysis (CMA) for detection of pathogenic copy number variants (CNVs) comprising medically-actionable genes. Clinical CMA has been performed on 8865 individuals referred for molecular cytogenetic testing. We retrospectively reviewed the CMA results to identify patients with CNVs comprising genes included in the 59-ACMG list of secondary findings. We evaluated the clinical significance of these CNVs in respect to pathogenicity, phenotypic manifestations, and heritability. We identified 23 patients (0.26%) with relevant CNV either deletions comprising the entire gene or intragenic alterations involving one or more secondary findings genes. A number of patients and/or their family members with pathogenic CNVs manifest or expected to develop an anticipated clinical phenotype and would benefit from preventive management similar to the patients with pathogenic SNVs. To improve patients' care standardization should apply to reporting of both sequencing and CNVs obtained via clinical genome-wide analysis, including chromosomal microarray and exome/genome sequencing.

COPY NUMBER LOSSES IN SPECIFIC REGIONS OF COMMON VARIATION ARE SIGNIFICANTLY MORE PREVALENT IN INFERTILITY PATIENTS COMPARED WITH A POPULATION OF DEMONSTRATED FERTILITY AND LOW FETAL WASTAGE

Chromosomal microarray analysis (CMA) is a valuable standard of care for assessment of individuals with developmental disabilities and other pathological states. However, interpretation of incident copy number variants (CNV) is highly dependent upon use of prevalence data from “normal” populations. Infertility which is present in up to 15% of any population is known to be genetically heterogeneous, however such patients would typically appear in CNV databases in the “normal” population and relevant findings may go unsuspected. We performed bioinformatic analysis of the variation observed in 539 consecutive women receiving services at a major US Infertility practice for the presence of potentially relevant CNV relating to their underlying condition or unsuspected genetic risks. We compared these to a population of 79 women with exceptional fertility (grand multiparas) as demonstrated by 5 or more uncomplicated term deliveries with no clinically apparent reproductive losses. CNV were assessed with an FDA approved CMA (Affymetrix, CytoscanDX). CNV association analysis of the entire databases of CNV segments in the “infertile” and “grand multipara” cohorts was undertaken with ParseCNV program (http://parsecnv.sourceforge.net/). A typically wide range of CNV and runs of homozygosity (ROH) was observed, with many overlapping known common regions of variation and the majority predicted to be likely benign. Potential impactful rare gene findings have been reported elsewhere, including two well described recurrent pathogenic CNV observed in 3 patients each, and an appreciable number of deletions encompassing all or part of genes for known over 40 autosomal recessive conditions suggesting CNV analysis would add positively to expanded carrier screening programs. A striking presence of genomic deletions in three regions in the “infertile” cohort (6-18%), none of which were observed in any of the “grand multiparas” (p value range: 0.02-≤0.000005) We used one-sided Fisher's exact test to test for enrichment of either deletion or duplication CNVs between the “infertile” case subjects and the comparison individuals. These differential CNVs all occurred in regions of common well-known CNV of gene families on chromosomes (chr) 7, 14, and 11 (typically 12-40% prevalence range for regions; Database of Genomic Variants [DGV]; http://dgv.tcag.ca/). There was no difference in the relative occurrence of any duplications or ROH. Deletions significantly differential in prevalence between these groups were observed in several regions of very common known CNV, which may have plausible link to key theories on reproductive success and evolution. The variants observed on the first two regions (chr7 & 14) involved variant transcripts of the T-cell receptor-g and -a respectively. On chromosome 11 the deletions involved the 52N1 and 52N5 families of olfactory receptor genes. Both the immune response and olfactory perceptions have been suggested to be involved with the evolution of eutherian mammalian reproduction and fertility in humans.

Estimating the effects of copy-number variants on intelligence using hierarchical Bayesian models.

It is challenging to estimate the phenotypic impact of the structural genome changes known as copy-number variations (CNVs), since there are many unique CNVs which are nonrecurrent, and most are too rare to be studied individually. In recent work, we found that CNV-aggregated genomic annotations, that is, specifically the intolerance to mutation as measured by the pLI score (probability of being loss-of-function intolerant), can be strong predictors of intellectual quotient (IQ) loss. However, this aggregation method only estimates the individual CNV effects indirectly. Here, we propose the use of hierarchical Bayesian models to directly estimate individual effects of rare CNVs on measures of intelligence. Annotation information on the impact of major mutations in genomic regions is extracted from genomic databases and used to define prior information for the approach we call HBIQ. We applied HBIQ to the analysis of CNV deletions and duplications from three datasets and identified several genomic regions containing CNVs demonstrating significant deleterious effects on IQ, some of which validate previously known associations. We also show that several CNVs were identified as deleterious by HBIQ even if they have a zero pLI score, and the converse is also true. Furthermore, we show that our new model yields higher out-of-sample concordance (78%) for predicting the consequences of carrying known recurrent CNVs compared with our previous approach.

Population prevalence and inheritance pattern of recurrent CNVs associated with neurodevelopmental disorders in 12,252 newborns and their parents

Recurrent copy number variations (CNVs) are common causes of neurodevelopmental disorders (NDDs) and associated with a range of psychiatric traits. These CNVs occur at defined genomic regions that are particularly prone to recurrent deletions and duplications and often exhibit variable expressivity and incomplete penetrance. Robust estimates of the population prevalence and inheritance pattern of recurrent CNVs associated with neurodevelopmental disorders (NDD CNVs) are lacking. Here we perform array-based CNV calling in 12,252 mother–father–child trios from the Norwegian Mother, Father, and Child Cohort Study (MoBa) and analyse the inheritance pattern of 26 recurrent NDD CNVs in 13 genomic regions. We estimate the total prevalence of recurrent NDD CNVs (duplications and deletions) in live-born children to 0.48% (95% C.I.: 0.37–0.62%), i.e., ~1 in 200 newborns has either a deletion or duplication in these NDDs associated regions. Approximately a third of the newborn recurrent NDD CNVs (34%, N = 20/59) are de novo variants. We provide prevalence estimates and inheritance information for each of the 26 NDD CNVs and find higher prevalence than previously reported for 1q21.1 deletions (~1:2000), 15q11.2 duplications (~1:4000), 15q13.3 microdeletions (~1:2500), 16p11.2 proximal microdeletions (~1:2000) and 17q12 deletions (~1:4000) and lower than previously reported prevalence for the 22q11.2 deletion (~1:12,000). In conclusion, our analysis of an unselected and representative population of newborns and their parents provides a clearer picture of the rate of recurrent microdeletions/duplications implicated in neurodevelopmental delay. These results will provide an important resource for genetic diagnostics and counseling.

Ancestry and frequency of genetic variants in the general population are confounders in the characterization of germline variants linked to cancer

BackgroundPediatric high-grade gliomas (pHGGs) are incurable malignant brain cancers. Clear somatic genetic drivers are difficult to identify in the majority of cases. We hypothesized that this may be due to the existence of germline variants that influence tumor etiology and/or progression and are filtered out using traditional pipelines for somatic mutation calling.MethodsIn this study, we analyzed whole-genome sequencing (WGS) datasets of matched germlines and tumor tissues to identify recurrent germline variants in pHGG patients.ResultsWe identified two structural variants that were highly recurrent in a discovery cohort of 8 pHGG patients. One was a ~ 40 kb deletion immediately upstream of the NEGR1 locus and predicted to remove the promoter region of this gene. This copy number variant (CNV) was present in all patients in our discovery cohort (n = 8) and in 86.3% of patients in our validation cohort (n = 73 cases). We also identified a second recurrent deletion 55.7 kb in size affecting the BTNL3 and BTNL8 loci. This BTNL3–8 deletion was observed in 62.5% patients in our discovery cohort, and in 17.8% of the patients in the validation cohort. Our single-cell RNA sequencing (scRNA-seq) data showed that both deletions result in disruption of transcription of the affected genes. However, analysis of genomic information from multiple non-cancer cohorts showed that both the NEGR1 promoter deletion and the BTNL3–8 deletion were CNVs occurring at high frequencies in the general population. Intriguingly, the upstream NEGR1 CNV deletion was homozygous in ~ 40% of individuals in the non-cancer population. This finding was immediately relevant because the affected genes have important physiological functions, and our analyses showed that NEGR1 expression levels have prognostic value for pHGG patient survival. We also found that these deletions occurred at different frequencies among different ethnic groups.ConclusionsOur study highlights the need to integrate cancer genomic analyses and genomic data from large control populations. Failure to do so may lead to spurious association of genes with cancer etiology. Importantly, our results showcase the need for careful evaluation of differences in the frequency of genetic variants among different ethnic groups.