Background: Several copy number variants (CNVs) are associated with a high risk of neurodevelopmental and psychiatric disorders (referred to as ND-CNVs). We aimed to characterise the effect of ND-CNVs on childhood development and investigate whether different ND-CNVs lead to distinct and specific patterns of cognitive and behavioural outcomes.
Methods: In this case-control study, we used data from the Intellectual Disability and Mental Health: Assessing the Genomic Impact on Neurodevelopment (IMAGINE-ID) study. Children aged 4 years and older with pathogenic CNV or single nucleotide variants were recruited via the UK National Health Service (NHS) medical genetic clinic network and via patient support groups to complete broad online phenotyping, from whom children aged 6-19 years with at least one of a specific group of ND-CNVs (1q21.1 [proximal duplication, and distal deletion and duplication], 2p16.3 deletion, 9q34.3 deletion, 15q11.2 deletion, 15q13.3 deletion and duplication, 16p11.2 [proximal deletion and duplication, and distal deletion], and 22q11.2 deletion and duplication) and their families were approached for a deep phenotyping, home-based assessment, and we report on this sample here. We invited siblings of index children to participate as controls, for whom the presence of ND-CNVs was excluded by use of microarray results and also medical records where possible. We systematically assessed the children for psychiatric disorders and broader traits of neurodevelopmental, cognitive, and psychopathological origin and compared results of ND-CNV carriers with control siblings to test the hypothesis that phenotypes would differ by genotype, both quantitatively in terms of severity and qualitatively in the pattern of associated impairments.
Findings: Between Oct 1, 2014, and Dec 31, 2018, of 2819 children recruited, 258 (9%) had one ND-CNV of interest, with 13 CNVs across nine loci, and underwent a home-based assessment. 106 control siblings were enrolled. 186 (80%) of ND-CNV carriers met criteria for one or more psychiatric disorder (odds ratio [OR] 13·8, 95% CI 7·2-26·3, compared with controls). The risk of attention-deficit hyperactivity disorder (OR 6·9, 3·2-15·1), oppositional defiant disorder (OR 3·6, 1·4-9·4), any anxiety disorder (OR 2·9, 1·2-6·7), and autism spectrum disorder traits (OR 44·1, 15·3-127·5) was particularly high compared with controls. ND-CNV carriers were impaired across all neurodevelopmental, cognitive, and psychopathological traits compared with controls. Only moderate quantitative and qualitative differences in phenotypic profile were found between genotypes. Overall, the range of phenotypes was broadly similar for all ND-CNV genotypes. Traits did show some evidence of genotypic specificity, with rank-based analyses showing moderate qualitative and quantitative profile differences between ND-CNVs; however, the specific genotype accounted for a low proportion of variance in cognitive and behavioural outcomes (approximately 5-20% depending on the trait).
Interpretation: The 13 ND-CNVs studied have a similar range of adverse effects on childhood neurodevelopment, despite subtle quantitative and qualitative differences. Genomic risk for neuropsychiatric disorder has pleiotropic effects on multiple processes and neural circuits and indicates that future research should avoid being narrowly focused on single phenotypes.
Funding: UK Medical Research Council and Medical Research Foundation.
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