Rare chromosomal deletions and duplications in attention-deficit hyperactivity disorder: a genome-wide analysis

Abstract

SummaryBackgroundLarge, rare chromosomal deletions and duplications known as copy number variants (CNVs) have been implicated in neurodevelopmental disorders similar to attention-deficit hyperactivity disorder (ADHD). We aimed to establish whether burden of CNVs was increased in ADHD, and to investigate whether identified CNVs were enriched for loci previously identified in autism and schizophrenia.MethodsWe undertook a genome-wide analysis of CNVs in 410 children with ADHD and 1156 unrelated ethnically matched controls from the 1958 British Birth Cohort. Children of white UK origin, aged 5–17 years, who met diagnostic criteria for ADHD or hyperkinetic disorder, but not schizophrenia and autism, were recruited from community child psychiatry and paediatric outpatient clinics. Single nucleotide polymorphisms (SNPs) were genotyped in the ADHD and control groups with two arrays; CNV analysis was limited to SNPs common to both arrays and included only samples with high-quality data. CNVs in the ADHD group were validated with comparative genomic hybridisation. We assessed the genome-wide burden of large (>500 kb), rare (<1% population frequency) CNVs according to the average number of CNVs per sample, with significance assessed via permutation. Locus-specific tests of association were undertaken for test regions defined for all identified CNVs and for 20 loci implicated in autism or schizophrenia. Findings were replicated in 825 Icelandic patients with ADHD and 35 243 Icelandic controls.FindingsData for full analyses were available for 366 children with ADHD and 1047 controls. 57 large, rare CNVs were identified in children with ADHD and 78 in controls, showing a significantly increased rate of CNVs in ADHD (0·156 vs 0·075; p=8·9×10−5). This increased rate of CNVs was particularly high in those with intellectual disability (0·424; p=2·0×10−6), although there was also a significant excess in cases with no such disability (0·125, p=0·0077). An excess of chromosome 16p13.11 duplications was noted in the ADHD group (p=0·0008 after correction for multiple testing), a finding that was replicated in the Icelandic sample (p=0·031). CNVs identified in our ADHD cohort were significantly enriched for loci previously reported in both autism (p=0·0095) and schizophrenia (p=0·010).InterpretationOur findings provide genetic evidence of an increased rate of large CNVs in individuals with ADHD and suggest that ADHD is not purely a social construct.FundingAction Research; Baily Thomas Charitable Trust; Wellcome Trust; UK Medical Research Council; European Union.

Application of custom-designed oligonucleotide array CGH in 145 patients with autistic spectrum disorders

“…30 However, other reports associated this CNV with a variety of neuropsychiatric and neurobehavioral disorders, including autism, schizophrenia, intellectual disabilities, cognitive impairment, attention deficit hyperactivity disorder, and epilepsy, as well as congenital heart defects, skeletal manifestations, and thoracic aortic aneurysms and dissections. [31][32][33][34][35][36][37] We suggest that this duplication may contribute to the autistic features seen in patient 7.…”

How French media have portrayed ADHD to the lay public and to social workers

“…Of the eight articles supporting a major genetic causation for ADHD, only one echoed a scientific study. On 2 October 2010, the most respected French newspaper Le Monde echoed a study published in the prestigious medical journal The Lancet and claiming that DNA deletions or duplications are twice as frequent in ADHD children as in unaffected ones (Williams et al, 2010). Actually, the medical relevance of this study was weak: these DNA alterations were detected in 12.5% of ADHD children and 7.5% of unaffected ones.…”

A genome-wide study of panic disorder suggests the amiloride-sensitive cation channel 1 as a candidate gene

“…Using an isolated population provides increased power to our study to detect rare variants, which increasingly are being identified for common complex disorders. 36,37 Isolated populations might pose an advantage over outbreed populations in detecting rare variants, 38 as only a low number of each risk alleles is likely to be introduced into an isolated founder population. In this way, heterogeneity will be reduced, and the LD surrounding the risk variant will be confined to the population history of the isolate.…”