Rare Copy Research Articles

Copy Number Variant Risk Scores Associated With Cognition, Psychopathology, and Brain Structure in Youths in the Philadelphia Neurodevelopmental Cohort

Psychiatric and cognitive phenotypes have been associated with a range of specific, rare copy number variants (CNVs). Moreover, IQ is strongly associated with CNV risk scores that model the predicted risk of CNVs across the genome. But the utility of CNV risk scores for psychiatric phenotypes has been sparsely examined. To determine how CNV risk scores, common genetic variation indexed by polygenic scores (PGSs), and environmental factors combine to associate with cognition and psychopathology in a community sample. The Philadelphia Neurodevelopmental Cohort is a community-based study examining genetics, psychopathology, neurocognition, and neuroimaging. Participants were recruited through the Children's Hospital of Philadelphia pediatric network. Participants with stable health and fluency in English underwent genotypic and phenotypic characterization from November 5, 2009, through December 30, 2011. Data were analyzed from January 1 through July 30, 2021. The study examined (1) CNV risk scores derived from models of burden, predicted intolerance, and gene dosage sensitivity; (2) PGSs from genomewide association studies related to developmental outcomes; and (3) environmental factors, including trauma exposure and neighborhood socioeconomic status. The study examined (1) neurocognition, with the Penn Computerized Neurocognitive Battery; (2) psychopathology, with structured interviews based on the Schedule for Affective Disorders and Schizophrenia for School-Age Children; and (3) brain volume, with magnetic resonance imaging. Participants included 9498 youths aged 8 to 21 years; 4906 (51.7%) were female, and the mean (SD) age was 14.2 (3.7) years. After quality control, 18 185 total CNVs greater than 50 kilobases (10 517 deletions and 7668 duplications) were identified in 7101 unrelated participants genotyped on Illumina arrays. In these participants, elevated CNV risk scores were associated with lower overall accuracy on cognitive tests (standardized β = 0.12; 95% CI, 0.10-0.14; P = 7.41 × 10-26); lower accuracy across a range of cognitive subdomains; increased overall psychopathology; increased psychosis-spectrum symptoms; and higher deviation from a normative developmental model of brain volume. Statistical models of developmental outcomes were significantly improved when CNV risk scores were combined with PGSs and environmental factors. In this study, elevated CNV risk scores were associated with lower cognitive ability, higher psychopathology including psychosis-spectrum symptoms, and greater deviations from normative magnetic resonance imaging models of brain development. Together, these results represent a step toward synthesizing rare genetic, common genetic, and environmental factors to understand clinically relevant outcomes in youth.

The contribution of rare copy number variants in FAS toward pathogenesis of autoimmune lymphoproliferative syndrome

AbstractAutoimmune lymphoproliferative syndrome (ALPS) is characterized by chronic nonmalignant lymphadenopathy, splenomegaly, cytopenias, and other autoimmune manifestations. ALPS is caused by lymphocyte accumulation from defects in FAS-mediated apoptosis. Heterozygous germline or somatic pathogenic single nucleotide variants in FAS are the most common molecular etiology of ALPS. Through the Centralized Sequencing Program at the National Institute of Allergy and Infectious Diseases, we performed exome sequencing on subjects with a clinical diagnosis of ALPS, with a subset receiving copy number variant (CNV) analysis. In this cohort, we identified 3 subjects from unrelated families with CNVs at the FAS locus. One subject had a de novo ∼0.828 Mb copy number loss encompassing all of FAS. The second subject had a maternally inherited ∼1.004 Mb copy number loss encompassing all of FAS. The third subject had a paternally inherited ∼0.044 Mb copy number loss encompassing exons 7 through 9 of FAS. Subjects with deletions in FAS had clinical presentations and biomarker profiles similar to those with ALPS and with germline and somatic FAS variants. We demonstrate that CNV analysis should be pursued if there is clinical and biomarker evidence of ALPS because it can lead to a molecular diagnosis and appropriate treatment when FAS sequencing is inconclusive.

Schizophrenia Risk Mediated by microRNA Target Genes Overlapped by Genome-Wide Rare Copy Number Variation in 22q11.2 Deletion Syndrome.

The 22q11.2 deletion is associated with >20-fold increased risk for schizophrenia. The presence of gene DGCR8 in the 22q11.2 deletion region has suggested microRNA (miRNA) dysregulation as possibly contributing to this risk. We therefore investigated the role of miRNA target genes in the context of previously identified genome-wide risk for schizophrenia conveyed by additional copy number variation (CNV) in 22q11.2 deletion syndrome (22q11.2DS). Using a cohort of individuals with 22q11.2DS and documented additional rare CNVs overlapping protein coding genes, we compared those with schizophrenia (n = 100) to those with no psychotic illness (n = 118), assessing for rare CNVs that overlapped experimentally supported miRNA target genes. We further characterized the contributing miRNA target genes using gene set enrichment analyses and identified the miRNAs most implicated. Consistent with our hypothesis, we found a significantly higher proportion of individuals in the schizophrenia than in the non-psychotic group to have an additional rare CNV that overlapped one or more miRNA target genes (odds ratio = 2.12, p = 0.0138). Gene set analyses identified an enrichment of FMRP targets and genes involved in nervous system development and postsynaptic density amongst these miRNA target genes in the schizophrenia group. The miRNAs most implicated included miR-17-5p, miR-34a-5p and miR-124-3p. These results provide initial correlational evidence in support of a possible role for miRNA perturbation involving genes affected by rare genome-wide CNVs in the elevated risk for schizophrenia in 22q11.2DS, consistent with the multi-hit and multi-layered genetic mechanisms implicated in this and other forms of schizophrenia.

Identification of rare mutations of the vasoactive intestinal peptide receptor 2 gene in schizophrenia.

Studies showed that rare copy number variations (CNVs) encompassing the vasoactive intestinal peptide receptor 2 gene (VIPR2) were associated with schizophrenia, indicating VIPR2 is a risk gene for schizophrenia. We hypothesized that besides CNV, rare pathogenic single-nucleotide variant (SNV) or small insertion/deletion (Indel) of VIPR2 might be present in some patients and contribute to the pathogenesis of schizophrenia. We performed genome-wide CNV analysis to screen CNV at the VIPR2 locus and targeted sequencing of all the exons of VIPR2 to search for SNV and indel in a sample of patients with chronic schizophrenia from Taiwan. We detected a 230-kb microduplication encompassing the VIPR2 in 1 out of 200 patients. Furthermore, we identified six ultrarare SNVs, including one splicing SNV and five missense SNVs, in 516 patients. In-silico analyses showed these SNVs had a damaging effect on the function of VIPR2. Our findings support the idea that besides CNV, rare pathogenic SNVs of VIPR2 might contribute to the pathogenesis of schizophrenia in some patients.

Pleotropic Effects of 15q13.3 Microdeletion on Interneuron Development: Insight on Spatiotemporal Molecular Events Leading to Neurodevelopmental Disorders

Some rare copy number variants (CNVs) that are either a microdeletion or a duplication of a specific genomic region containing several genes are associated with neurodevelopmental disorders. Typically, a CNV can cause multiple psychiatric phenotypes via complex pleotropic effects. This suggests that the pathological mechanisms resulting from the loss or duplication of several genes may be partially shared across psychiatric diseases. Thus, CNVs constitute highly valuable entry points to investigate the mechanisms of pathogenesis associated with neurodevelopmental disorders.

Targeted Exome Sequencing of Genes Involved in Rare CNVs in Early-Onset Severe Obesity.

Context: Rare copy number variants (CNVs) have been associated with the development of severe obesity. However, the potential disease-causing contribution of individual genes within the region of CNVs is often not known. Objective: Screening of rare variants in genes involved in CNVs in Finnish patients with severe early-onset obesity to find candidate genes linked to severe obesity. Methods: Custom-made targeted exome sequencing panel to search for rare (minor allele frequency <0.1%) variants in genes affected by previously identified CNVs in 92 subjects (median age 14 years) with early-onset severe obesity (median body mass index (BMI) Z-score + 4.0). Results: We identified thirteen rare heterozygous variants of unknown significance in eleven subjects in twelve of the CNV genes. Two rare missense variants (p.Pro405Arg and p.Tyr232Cys) were found in SORCS1, a gene highly expressed in the brain and previously linked to diabetes risk. Four rare variants were in genes in the proximal 16p11.2 region (a frameshift variant in TAOK2 and missense variants in SEZ6L2, ALDOA and KIF22) and three rare missense variants were in genes in the 22q11.21 region (AIFM3, ARVCF and KLHL22). Conclusion: We report several rare variants in CNV genes in subjects with childhood obesity. However, the role of the individual genes in the previously identified rare CNVs to development of obesity remains uncertain. More studies are needed to understand the potential role of the specific genes within obesity associated CNVs.

EP473: Patient attitudes and preferences about expanded noninvasive prenatal screening

The use of cell free DNA (cfDNA) screening for fetal aneuploidy by noninvasive prenatal screening (NIPS) has increased globally since its clinical introduction in 2011. Originally focused mainly on screening for common trisomies, NIPS is now available with other chromosomal conditions, such as sex chromosome aneuploidies (SCAs) and microdeletions, and more recently, rare autosomal aneuploidies (RAAs) and copy number variants (CNVs) across the genome, generally referred to as Expanded NIPS. There is a relative paucity in the literature regarding patients’ attitudes and preferences related to Expanded NIPS.

The COVID-19 pandemic's impact on worry and medical disruptions reported by individuals with chromosome 22q11.2 copy number variants and their caregivers.

The world has suffered immeasurably during the COVID-19 pandemic. Increased distress and mental and medical health concerns are collateral consequences to the disease itself. The Genes to Mental Health (G2MH) Network consortium sought to understand how individuals affected by the rare copy number variations of 22q11.2 deletion and duplication syndrome, associated with neurodevelopmental/neuropsychiatric conditions, were coping. The article focuses on worry and disruptions in medical care caused by the pandemic. The University of Pennsylvania COVID-19 Stressor List and care disruption questions were circulated by 22 advocacy groups in English and 11 other languages. A total of 512 people from 23 countries completed the survey; most were caregivers of affected individuals. Worry about family members acquiring COVID-19 had the highest average endorsed worry, whilst currently having COVID-19 had the lowest rated worry. Total COVID-19 worries were higher in individuals completing the survey towards the end of the study (later pandemic wave); 36% (n=186) of the sample reported a significant effect on health due to care interruption during the pandemic; 44% of individuals (n=111) receiving care for their genetic syndrome in a hospital setting reported delaying appointments due to COVID-19 fears; 12% (n=59) of the sample reported disruptions to treatments; and of those reporting no current disruptions, 59% (n=269) worried about future disruptions if the pandemic continued. Higher levels of care disruptions were related to higher COVID-19 worries (Ps<0.005). Minimal differences by respondent type or copy number variation type emerged. Widespread medical care disruptions and pandemic-related worries were reported by individuals with 22q11.2 syndrome and their family members. Reported worries were broadly consistent with research results from prior reports in the general population. The long-term effects of COVID-19 worries, interruptions to care and hospital avoidance require further study.

Clinical Characterization of Copy Number Variants Associated With Neurodevelopmental Disorders in a Large-scale Multiancestry Biobank

Past studies identified rare copy number variants (CNVs) as risk factors for neurodevelopmental disorders (NDDs), including autism spectrum disorder and schizophrenia. However, the clinical characterization of NDD CNVs is understudied in population cohorts unselected for neuropsychiatric disorders and in cohorts of diverse ancestry. To identify individuals harboring NDD CNVs in a multiancestry biobank and to query their enrichment for select neuropsychiatric disorders as well as association with multiple medical disorders. In a series of phenotypic enrichment and association analyses, NDD CNVs were clinically characterized among 24 877 participants in the BioMe biobank, an electronic health record-linked biobank derived from the Mount Sinai Health System, New York, New York. Participants were recruited into the biobank since September 2007 across diverse ancestry and medical and neuropsychiatric specialties. For the current analyses, electronic health record data were analyzed from May 2004 through May 2019. NDD CNVs were identified using a consensus of 2 CNV calling algorithms, based on whole-exome sequencing and genotype array data, followed by novel in-silico clinical assessments. Of 24 877 participants, 14 586 (58.7%) were female; self-reported ancestry categories included 5965 (24.0%) who were of African ancestry, 7892 (31.7%) who were of European ancestry, and 8536 (34.3%) who were of Hispanic ancestry; and the mean (SD) age was 50.5 (17.3) years. Among 24 877 individuals, the prevalence of 64 NDD CNVs was 2.5% (n = 627), with prevalence varying by locus, corroborating the presence of some relatively highly prevalent NDD CNVs (eg, 15q11.2 deletion/duplication). An aggregate set of NDD CNVs were enriched for congenital disorders (odds ratio, 2.0; 95% CI, 1.1-3.5; P = .01) and major depressive disorder (odds ratio, 1.5; 95% CI, 1.1-2.0; P = .01). In a meta-analysis of medical diagnoses (n = 195 hierarchically clustered diagnostic codes), NDD CNVs were significantly associated with several medical outcomes, including essential hypertension (z score = 3.6; P = 2.8 × 10-4), kidney failure (z score = 3.3; P = 1.1 × 10-3), and obstructive sleep apnea (z score = 3.4; P = 8.1 × 10-4) and, in another analysis, morbid obesity (z score = 3.8; P = 1.3 × 10-4). Further, NDD CNVs were associated with increased body mass index in a multiancestry analysis (β = 0.19; 95% CI, 0.10-0.31; P = .003). For 36 common serum tests, there was no association with NDD CNVs. Clinical features of individuals harboring NDD CNVs were elucidated in a large-scale, multiancestry biobank, identifying enrichments for congenital disorders and major depressive disorder as well as associations with several medical outcomes, including hypertension, kidney failure, and obesity and obesity-related phenotypes, specifically obstructive sleep apnea and increased body mass index. The association between NDD CNVs and obesity outcomes indicate further potential pleiotropy of NDD CNVs beyond neurodevelopmental outcomes previously reported. Future clinical genetic investigations may lead to insights of at-risk individuals and therapeutic strategies targeting specific genetic variants. The importance of diverse inclusion within biobanks and considering the effect of rare genetic variants in a multiancestry context is evident.

Identification of Novel Gene Variants for Autism Spectrum Disorders in the Lebanese Population Using Whole-Exome Sequencing.

In our previous study, in which array CGH was used on 19 Lebanese ASD subjects and their parents, we identified rare copy number variants (CNVs) in 14 subjects. The five remaining subjects did not show any CNVs related to autism spectrum disorders (ASD). In the present complementary study, we applied whole-exome sequencing (WES), which allows the identification of rare genetic variations such as single nucleotide variations and small insertions/deletions, to the five negative CNV subjects. After stringent filtering of initial data on the five families, three novel genes potentially related to neurodevelopment were identified, including a de novo mutation in the MIS18BP1 gene. In addition, genes already known to be related to ASD contained sequence variations. Our findings outline the potential involvement of the novel de novo mutation in the MIS18BP1 gene in the genetic etiology and pathophysiology of ASD and highlights the genetic complexity of these disorders. Further studies with larger cohorts of subjects are needed to confirm these observations, and functional analyses need to be performed to understand the precise pathophysiology in these cases.

Rare germline copy number variants (CNVs) and breast cancer risk

Germline copy number variants (CNVs) are pervasive in the human genome but potential disease associations with rare CNVs have not been comprehensively assessed in large datasets. We analysed rare CNVs in genes and non-coding regions for 86,788 breast cancer cases and 76,122 controls of European ancestry with genome-wide array data. Gene burden tests detected the strongest association for deletions in BRCA1 (P = 3.7E−18). Nine other genes were associated with a p-value < 0.01 including known susceptibility genes CHEK2 (P = 0.0008), ATM (P = 0.002) and BRCA2 (P = 0.008). Outside the known genes we detected associations with p-values < 0.001 for either overall or subtype-specific breast cancer at nine deletion regions and four duplication regions. Three of the deletion regions were in established common susceptibility loci. To the best of our knowledge, this is the first genome-wide analysis of rare CNVs in a large breast cancer case-control dataset. We detected associations with exonic deletions in established breast cancer susceptibility genes. We also detected suggestive associations with non-coding CNVs in known and novel loci with large effects sizes. Larger sample sizes will be required to reach robust levels of statistical significance.

Initial Clinical Experience with NIPT for Rare Autosomal Aneuploidies and Large Copy Number Variations.

Objective: Amniocentesis, chorionic villi sampling and first trimester combined testing are able to screen for common trisomies 13, 18, and 21 and other atypical chromosomal anomalies (ACA). The most frequent atypical aberrations reported are rare autosomal aneuploidies (RAA) and copy number variations (CNV), which are deletions or duplications of various sizes. We evaluated the clinical outcome of non-invasive prenatal testing (NIPT) results positive for RAA and large CNVs to determine the clinical significance of these abnormal results. Methods: Genome-wide NIPT was performed on 3664 eligible patient samples at a single genetics center. For patients with positive NIPT reports, the prescribing physician was asked retrospectively to provide clinical follow-up information using a standardized questionnaire. Results: RAAs and CNVs (>7 Mb) were detected in 0.5%, and 0.2% of tested cases, respectively. Follow up on pregnancies with an NIPT-positive result for RAA revealed signs of placental insufficiency or intra-uterine death in 50% of the cases and normal outcome at the time of birth in the other 50% of cases. We showed that CNV testing by NIPT allows for the detection of unbalanced translocations and relevant maternal health conditions. Conclusion: NIPT for aneuploidies of all autosomes and large CNVs of at least 7 Mb has a low “non-reportable”-rate (<0.2%) and allows the detection of additional conditions of clinical significance.

Multi-site Normative Modeling of Diffusion Tensor Imaging Metrics Using Hierarchical Bayesian Regression.

Multi-site imaging studies can increase statistical power and improve the reproducibility and generalizability of findings, yet data often need to be harmonized. One alternative to data harmonization in the normative modeling setting is Hierarchical Bayesian Regression (HBR), which overcomes some of the weaknesses of data harmonization. Here, we test the utility of three model types, i.e., linear, polynomial and b-spline - within the normative modeling HBR framework - for multi-site normative modeling of diffusion tensor imaging (DTI) metrics of the brain's white matter microstructure, across the lifespan. These models of age dependencies were fitted to cross-sectional data from over 1,300 healthy subjects (age range: 2-80 years), scanned at eight sites in diverse geographic locations. We found that the polynomial and b-spline fits were better suited for modeling relationships of DTI metrics to age, compared to the linear fit. To illustrate the method, we also apply it to detect microstructural brain differences in carriers of rare genetic copy number variants, noting how model complexity can impact findings.

Альманах Королевы Ольги с автографами Белой эмиграции на аукционе в Монако 2018 г.

The present study describes in detail a rare copy of the literary almanac “From Day to Day” in 1886, presented to persons from the closest circle of the Great Princess Elizaveta Feodorovna by its compiler, the Greek Queen Olga (1951–1926), six months before her death, in January 1926. This is evidenced by the preserved records and the queen's gift to the Strukov couple. The small circulation of the book, the unusual fate of each of the identified copies of the almanac, determined the interest in the copy of the auction sale in Monaco. The album contains recordings of famous benefactors of Russia — the Strukovs, Countess A. A. Olsufyeva (state lady of the Empress Alexandra Feodorovna), Princess M. V. Baryatinskaya (state lady of the Empress Maria Feodorovna). There are autographs of Duke Ernst of Hesse, the brother of the Grand Duchess Elizabeth, and his wife, other famous people, many of whom were parishioners of the Florentine church of St. Nicholas, who belonged to the community of Metropolitan Eulogy (Georgievsky), a well-known figure of the Russian Church Abroad.

Translational Study of Copy Number Variations in Schizophrenia.

Rare copy number variations (CNVs) are part of the genetics of schizophrenia; they are highly heterogeneous and personalized. The CNV Analysis Group of the Psychiatric Genomic Consortium (PGC) conducted a large-scale analysis and discovered that recurrent CNVs at eight genetic loci were pathogenic to schizophrenia, including 1q21.1, 2p16.3 (NRXN1), 3q29, 7q11.23, 15q13.3, distal 16p11.2, proximal 16p11.2, and 22q11.2. We adopted a two-stage strategy to translate this knowledge into clinical psychiatric practice. As a screening test, we first developed a real-time quantitative PCR (RT-qPCR) panel that simultaneously detected these pathogenic CNVs. Then, we tested the utility of this screening panel by investigating a sample of 557 patients with schizophrenia. Chromosomal microarray analysis (CMA) was used to confirm positive cases from the screening test. We detected and confirmed thirteen patients who carried CNVs at these hot loci, including two patients at 1q21.1, one patient at 7q11.2, three patients at 15q13.3, two patients at 16p11.2, and five patients at 22q11.2. The detection rate in this sample was 2.3%, and the concordance rate between the RT-qPCR test panel and CMA was 100%. Our results suggest that a two-stage approach is cost-effective and reliable in achieving etiological diagnosis for some patients with schizophrenia and improving the understanding of schizophrenia genetics.

Whole genome sequencing analysis of cognitively Wellderly individuals identifies potential protective genetic variants for Alzheimer's disease.

Genetic variants that confer protection from Alzheimer's disease (AD) may be particularly critical in developing therapeutics. To target protective variant identification, we performed genetic association testing among selected individuals with whole genome sequencing (WGS) that remained alive and dementia-free beyond age 85 ("Wellderly"). We selected 1,873 White and Black Wellderly individuals with documented normal cognition beyond age 85 as determined by direct, in-person assessment from three cohorts (FHS, CHS, and ARIC) with WGS from the NHLBI TOPMed project. We used two sets of comparison groups from these three cohorts: (i) general controls, non-Wellderly individuals including persons without and with dementia [n=8,502] and (ii) individuals who developed dementia before age 85 [n=810]. We performed generalized mixed model regression for binary outcomes using Wellderly status, separately with each comparison group, for each variant with a minor allele frequency (MAF) > 1%, adjusting for study and principal components of ancestry as fixed effects, and a genetic-relatedness matrix as a random effect to account for relatedness and shared ancestry. Additionally, we performed association testing adjusting for APOE e4 status. Our top results outside of the APOE locus tended to be more significant after adjusting for APOE e4 status. We observed a reduced risk of Wellderly status compared to general controls at the APOE locus (rs429358, MAF=14%, odds ratio [OR] = -0.40, p=1.6x10-10 ), consistent with the known association of the APOE locus with dementia. Additionally, we found suggestive associations at CACNA2D3 (rs73085981, MAF=16%, OR=1.44, p=6.7x10-8 ), ASTN2 (rs7350805, MAF=1%, OR=1.10, p=4.3x10-7 ), and YEATS4 (rs167588, MAF=1%, OR=1.1, p=3.7x10-7 ) using the general controls adjusting for APOE e4 status. CACNA2D3 and ASTN2 have plausible biological connections to AD. CACNA2D3 is a calcium channel gene and rare copy number variation has been implicated in voltage gate calcium channel genes in individuals with late-onset AD. ASTN2 encodes a protein that is expressed in the brain and may function in neuronal migration, and has been previously implicated in age of onset of AD and is associated with hippocampal volume. Although only variants in the APOE locus reached a genome-wide significance threshold, we found suggestive associations for Wellderly status with biological plausibility.

De novo germline mutation in the dual specificity phosphatase 10 gene accelerates autoimmune diabetes

Insulin-dependent or type 1 diabetes (T1D) is a polygenic autoimmune disease. In humans, more than 60 loci carrying common variants that confer disease susceptibility have been identified by genome-wide association studies, with a low individual risk contribution for most variants excepting those of the major histocompatibility complex (MHC) region (40 to 50% of risk); hence the importance of missing heritability due in part to rare variants. Nonobese diabetic (NOD) mice recapitulate major features of the human disease including genetic aspects with a key role for the MHC haplotype and a series of Idd loci. Here we mapped in NOD mice rare variants arising from genetic drift and significantly impacting disease risk. To that aim we established by selective breeding two sublines of NOD mice from our inbred NOD/Nck colony exhibiting a significant difference in T1D incidence. Whole-genome sequencing of high (H)- and low (L)-incidence sublines (NOD/NckH and NOD/NckL) revealed a limited number of subline-specific variants. Treating age of diabetes onset as a quantitative trait in automated meiotic mapping (AMM), enhanced susceptibility in NOD/NckH mice was unambiguously attributed to a recessive missense mutation of Dusp10, which encodes a dual specificity phosphatase. The causative effect of the mutation was verified by targeting Dusp10 with CRISPR-Cas9 in NOD/NckL mice, a manipulation that significantly increased disease incidence. The Dusp10 mutation resulted in islet cell down-regulation of type I interferon signature genes, which may exert protective effects against autoimmune aggression. De novo mutations akin to rare human susceptibility variants can alter the T1D phenotype.

Copy number variations in a Brazilian cohort with autism spectrum disorders highlight the contribution of cell adhesion genes.

Prediction of pathogenicity of rare copy number variations (CNVs), a genomic alteration known to contribute to the etiology of autism spectrum disorder (ASD), represents a serious limitation to interpreting genetic tests, particularly for genetic counseling purposes. Chromosomal microarray analysis (CMA) was conducted in a unique collection of 144 Brazilian individuals with ASD of strong European and African ancestries. Rare CNVs were detected in 39 patients: 41 of unknown significance (VUS), four pathogenic and one likely pathogenic CNVs (clinical yield of 4.1%; 5/122). Based on gene content and recurrence in three large cohorts [a Brazilian neurodevelopmental disorder cohort, the autism MSSNG cohort, and the Canadian-based Centre for Applied Genomics microarray database], this work strengthened the pathogenicity of 14 genes (FAT1, CAMK4, BIRC6, DPP6, CSMD1, CTNNA3, CDH8/CDH11, CDH13, OR1C1, CNTN6, CNTNAP4, FGF2 and PTPRN2) within 14 CNVs. Notably, enrichment of cell adhesion proteins to ASD etiology was identified (p < 0.05), highlighting the importance of these gene families in the etiology of ASD.

Whole-genome sequencing: identification of additional pathogenic variation across the genome.

This scientific commentary refers to ‘Genome sequencing identifies rare tandem repeat expansions and copy number variants in Lennox–Gastaut syndrome’, by Qaiser et al. (https://doi.org/10.1093/braincomms/fcab207).

Identification of Vulnerable Interneuron Subtypes in 15q13.3 Microdeletion Syndrome Using Single-Cell Transcriptomics

BackgroundA number of rare copy number variants (CNVs) have been linked to neurodevelopmental disorders. However, because CNVs encompass many genes, it is often difficult to identify the mechanisms that lead to developmental perturbations. MethodsWe used 15q13.3 microdeletion to propose and validate a novel strategy to predict the impact of CNV genes on brain development that could further guide functional studies. We analyzed single-cell transcriptomics datasets containing cortical interneurons to identify their developmental vulnerability to 15q13.3 microdeletion, which was validated in mouse models. ResultsWe found that Klf13—but not other 15q13.3 genes—is expressed by precursors and neuroblasts in the medial and caudal ganglionic eminences during development, with a peak of expression at embryonic day (E)13.5 and E18.5, respectively. In contrast, in the adult mouse brain, Klf13 expression is negligible. Using Df(h15q13.3)/+ and Klf13+/− embryos, we observed a precursor subtype-specific impairment in proliferation in the medial ganglionic eminence and caudal ganglionic eminence at E13.5 and E17.5, respectively, corresponding to vulnerability predicted by Klf13 expression patterns. Finally, Klf13+/− mice showed a layer-specific decrease in parvalbumin and somatostatin cortical interneurons accompanied by changes in locomotor and anxiety-related behavior. ConclusionsWe show that the impact of 15q13.3 microdeletion on precursor proliferation is grounded in a reduction in Klf13 expression. The lack of Klf13 in Df(h15q13.3)/+ cortex might be the major reason for perturbed density of cortical interneurons. Thus, the behavioral defects seen in 15q13.3 microdeletion could stem from a developmental perturbation owing to selective vulnerability of cortical interneurons during sensitive stages of their development.