Refining analyses of copy number variation identifies specific genes associated with developmental delay (original) (raw)
Related papers
Copy-number variants in neurodevelopmental disorders: promises and challenges
Trends in Genetics, 2009
Copy-number variation (CNV) is the most prevalent type of structural variation in the human genome. There is emerging evidence that copy-number variants (CNVs) provide a new vista on understanding susceptibility to neuropsychiatric disorders. Some challenges in the interpretation of current CNV studies include the use of overlapping samples, differing phenotypic definitions, an absence of population norms for CNVs and a lack of consensus in methods for CNV detection and analysis. Here, we review current CNV association study methods and results in autism spectrum disorders (ASD) and schizophrenia, and provide suggestions for design approaches to future studies that might maximize the translation of this work to etiological understanding.
Journal of the American Academy of Child & Adolescent Psychiatry, 2013
Objective-The purpose of the present study is to discover the extent to which distinct DSM disorders share large, highly recurrent copy number variants (CNVs) as susceptibility factors. We also seek to identify gene mechanisms common to groups of diagnoses and/or specific to a given diagnosis based on associations with CNVs. Method-Systematic review of 820 PubMed articles on autism spectrum disorder (ASD), intellectual disability (ID), schizophrenia, and epilepsy produced 54 CNVs associated with one or several disorders. Pathway analysis on genes implicated by CNVs in different groupings was conducted. Results-The majority of CNVs were found in ID with the other disorders somewhat subsumed, yet certain CNVs were associated with isolated or groups of disorders. Based on genes implicated by CNVs, ID encompassed 96.8% of genes in ASD, 92.8% of genes in schizophrenia, and 100.0% of genes in epilepsy. Pathway analysis revealed that synapse processes were enriched in ASD, ID, and schizophrenia. Disease-specific processes were identified in ID (actin cytoskeleton processes), schizophrenia (ubiquitin-related processes), and ASD (synaptic vesicle transport and exocytosis).
Genome Medicine
Background Previous large-scale studies of de novo variants identified a number of genes associated with neurodevelopmental disorders (NDDs); however, it was also predicted that many NDD-associated genes await discovery. Such genes can be discovered by integrating copy number variants (CNVs), which have not been fully considered in previous studies, and increasing the sample size. Methods We first constructed a model estimating the rates of de novo CNVs per gene from several factors such as gene length and number of exons. Second, we compiled a comprehensive list of de novo single-nucleotide variants (SNVs) in 41,165 individuals and de novo CNVs in 3675 individuals with NDDs by aggregating our own and publicly available datasets, including denovo-db and the Deciphering Developmental Disorders study data. Third, summing up the de novo CNV rates that we estimated and SNV rates previously established, gene-based enrichment of de novo deleterious SNVs and CNVs were assessed in the 41,16...
A copy number variation morbidity map of developmental delay
Nature Genetics, 2011
To understand the genetic heterogeneity underlying developmental delay, we compare copynumber variants (CNVs) in 15,767 children with intellectual disability and various congenital defects to 8,329 adult controls. We estimate that ~14.2% of disease in these individuals is due to large CNVs > 400 kbp. We find greater CNV enrichment in patients with craniofacial anomalies and cardiovascular defects than epilepsy or autism. We identify 59 pathogenic CNVs including 14 novel or previously weakly supported candidates. We refine the critical interval for several genomic disorders such as the 17q21.31 microdeletion syndrome and identify 940 candidate dosage-sensitive genes. We also develop methods to opportunistically discover small, disruptive CNVs within the large and growing diagnostic array datasets. This evolving CNV morbidity map combined with exome/genome sequencing will be critical for deciphering the genetic basis of developmental delay, intellectual disability, and autism spectrum disorders.
A large data resource of genomic copy number variation across neurodevelopmental disorders
npj Genomic Medicine
Copy number variations (CNVs) are implicated across many neurodevelopmental disorders (NDDs) and contribute to their shared genetic etiology. Multiple studies have attempted to identify shared etiology among NDDs, but this is the first genome-wide CNV analysis across autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), schizophrenia (SCZ), and obsessive-compulsive disorder (OCD) at once. Using microarray (Affymetrix CytoScan HD), we genotyped 2,691 subjects diagnosed with an NDD (204 SCZ, 1,838 ASD, 427 ADHD and 222 OCD) and 1,769 family members, mainly parents. We identified rare CNVs, defined as those found in <0.1% of 10,851 population control samples. We found clinically relevant CNVs (broadly defined) in 284 (10.5%) of total subjects, including 22 (10.8%) among subjects with SCZ, 209 (11.4%) with ASD, 40 (9.4%) with ADHD, and 13 (5.6%) with OCD. Among all NDD subjects, we identified 17 (0.63%) with aneuploidies and 115 (4.3%) with known genomic di...
Indexing Effects of Copy Number Variation on Genes Involved in Developmental Delay
Scientific Reports, 2016
A challenge in clinical genomics is to predict whether copy number variation (CNV) affecting a gene or multiple genes will manifest as disease. Increasing recognition of gene dosage effects in neurodevelopmental disorders prompted us to develop a computational approach based on criticalexon (highly expressed in brain, highly conserved) examination for potential etiologic effects. Using a large CNV dataset, our updated analyses revealed significant (P < 1.64 × 10 −15) enrichment of critical-exons within rare CNVs in cases compared to controls. Separately, we used a weighted gene coexpression network analysis (WGCNA) to construct an unbiased protein module from prenatal and adult tissues and found it significantly enriched for critical exons in prenatal (P < 1.15 × 10 −50 , OR = 2.11) and adult (P < 6.03 × 10 −18 , OR = 1.55) tissues. WGCNA yielded 1,206 proteins for which we prioritized the corresponding genes as likely to have a role in neurodevelopmental disorders. We compared the gene lists obtained from critical-exon and WGCNA analysis and found 438 candidate genes associated with CNVs annotated as pathogenic, or as variants of uncertain significance (VOUS), from among 10,619 developmental delay cases. We identified genes containing CNVs previously considered to be VOUS to be new candidate genes for neurodevelopmental disorders (GIT1, MVB12B and PPP1R9A) demonstrating the utility of this strategy to index the clinical effects of CNVs. The broad umbrella classification of "developmental disorders" encompasses various conditions characterized by disturbance or delay of developmental milestones that appear in infancy or childhood. The cluster includes diagnostic entities that are themselves collectives, such as autism spectrum disorder (ASD), intellectual disability, learning disability, and others. The term may be used rather loosely, but is a common reason for referral to laboratories that offer genomic microarray for diagnostic evaluation. Developmental disorders affect ~3% of the population, and reflect a significant genetic contribution 1-3. In particular, large-scale genome-wide investigations 3-9 have
Human Molecular Genetics, 2012
Autism spectrum disorders (ASDs) are highly heritable, yet relatively few associated genetic loci have been replicated. Copy number variations (CNVs) have been implicated in autism; however, the majority of loci contribute to <1% of the disease population. Therefore, independent studies are important to refine associated CNV regions and discover novel susceptibility genes. In this study, a genome-wide SNP array was utilized for CNV detection by two distinct algorithms in a European ancestry case-control data set. We identify a significantly higher burden in the number and size of deletions, and disrupting more genes in ASD cases. Moreover, 18 deletions larger than 1 Mb were detected exclusively in cases, implicating novel regions at 2q22.1, 3p26.3, 4q12 and 14q23. Casespecific CNVs provided further evidence for pathways previously implicated in ASDs, revealing new candidate genes within the GABAergic signaling and neural development pathways. These include DBI, an allosteric binder of GABA receptors, GABARAPL1, the GABA receptor-associated protein, and SLC6A11, a postsynaptic GABA transporter. We also identified CNVs in COBL, deletions of which cause defects in neuronal cytoskeleton morphogenesis in model vertebrates, and DNER, a neuron-specific Notch ligand required for cerebellar development. Moreover, we found evidence of genetic overlap between ASDs and other neurodevelopmental and neuropsychiatric diseases. These genes include glutamate receptors (GRID1, GRIK2 and GRIK4), synaptic regulators (NRXN3, SLC6A8 and SYN3), transcription factor (ZNF804A) and RNA-binding protein FMR1. Taken together, these CNVs may be a few of the missing pieces of ASD heritability and lead to discovering novel etiological mechanisms.
A Critical Review of the Impact of Candidate Copy Number Variants on Autism Spectrum Disorders
arXiv (Cornell University), 2023
Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder (NDD) that is caused by genetic, epigenetic, and environmental factors. Recent advances in genomic analysis have uncovered numerous candidate genes with common and/or rare mutations that increase susceptibility to ASD. In addition, there is increasing evidence that copy number variations (CNVs), single nucleotide polymorphisms (SNPs), and unusual de novo variants negatively affect neurodevelopment pathways in various ways. The overall rate of copy number variants found in patients with autism is 10%-20%, of which 3%-7% can be detected cytogenetically. Although the role of submicroscopic CNVs in ASD has been studied recently, their association with genomic loci and genes has not been properly studied. In this review, we focus on 47 ASD-associated CNV regions and their related genes. Here, we identify 1,632 protein-coding genes and long non-coding RNAs (lncRNAs) within these regions. Among them, 552 are significantly expressed in the brain. Using a list of ASD-associated genes from SFARI, we detect 17 regions containing at least one known ASD-associated protein-coding genes. Of the remaining 30 regions, we identify 24 regions containing at least one proteincoding genes with brain-enriched expression and nervous system phenotype in mouse mutant and one lncRNAs with both brain-enriched expression and upregulation in iPSC to neuron differentiation. Our analyses highlight the diversity of genetic lesions of CNV regions that contribute to ASD and provide new genetic evidence that lncRNA genes may contribute to etiology of ASD. In addition, the discovered CNVs will be a valuable resource for diagnostic facilities, therapeutic strategies, and research in terms of variation priority.
Copy number variants in autism spectrum disorders
Progress in Neuro-Psychopharmacology and Biological Psychiatry, 2019
In recent years, there has been an explosive increase in genetic studies related to autism spectrum disorder (ASD). This implicated the accumulation of a large amount of molecular data that may be used to verify various hypotheses and models developed to explore the complex genetic component of ASD. Several lines of evidence support the view that structural genomic variation contributes to the pathogenesis of ASD. The introduction of more sophisticated techniques for whole-genome screening, including array comparative genome hybridization and high-resolution single nucleotide polymorphism analysis, has allowed to identify an increasing number of ASD susceptibility loci. Copy number variants (CNVs) are the most common type of structural variation in the human genome and are considered important contributors to the pathogenesis of neurodevelopmental disorders, including ASD. In this review, we describe the accumulated evidence concerning the genetic events associated with ASD, and summarize current knowledge about the clinical relevance of CNVs in these disorders.