Copy number variation and neurodevelopmental problems in females and males in the general population
ObjectiveNeurodevelopmental problems (NPs) are childhood phenotypes that are more common in males. Conversely, anxiety and depression (which are frequently comorbid with NPs) are more common in females. Rare copy number variants (CNVs) have been implicated in clinically-defined NPs. Here, we aimed to characterise the relationship between rare CNVs with NPs and anxiety/depression in a population sample of twin children. Additionally, we examined whether sex-specific CNV effects underlie the sex bias of these disorders.\n\nMethodWe analysed a sample of N=12,982 children, of whom 5.3% had narrowly-defined NPs (clinically-diagnosed), 20.9% had broadly-defined NPs (based on validated screening measures, but no diagnosis) and 3.0% had clinically-diagnosed anxiety or depression. Rare (<1% frequency) CNVs were categorised by size (medium: 100-500kb or large: >500kb), type (duplication or deletion) and putative relevance to NPs (affecting previously implicated loci or evolutionarily-constrained genes). We tested for associations between the different CNV categories with NPs and anxiety/depression, followed by examination of sex-specific effects.\n\nResultsMedium deletions (OR(CI)=1.18(1.05-1.33),p=0.0053) and large duplications (OR(CI)=1.45(1.19-1.75),p=0.00017) were associated with broadly-defined NPs. Large deletions (OR(CI)=1.85(1.14-3.01),p=0.013) were associated with narrowly-defined NPs. The effect sizes increased for large NP-relevant CNVs (broadly-defined: OR(CI)=1.60(1.06-2.42),p=0.025; narrowly-defined: OR(CI)=3.64(2.16-6.13),p=1.2E-6). No sex differences in CNV burden were found in individuals with NPs (p>0.05). In individuals diagnosed with anxiety or depression, females were more likely to have large CNVs (OR(CI)=3.75(1.45-9.68),p=0.0064).\n\nConclusionRare CNVs are significantly associated with both narrowly- and broadly-defined NPs in a general population sample of children. Our results also suggest that large, rare CNVs may show sex-specific phenotypic effects.