title: Neuropsychological endophenotype approach to genome-wide linkage analysis identifies susceptibility loci for ADHD on 2q21.1 and 13q12.11.
abstract: ADHD linkage findings have not all been consistently replicated, suggesting that other approaches to linkage analysis in ADHD might be necessary, such as the use of (quantitative) endophenotypes (heritable traits associated with an increased risk for ADHD). Genome-wide linkage analyses were performed in the Dutch subsample of the International Multi-Center ADHD Genetics (IMAGE) study comprising 238 DSM-IV combined-type ADHD probands and their 112 affected and 195 nonaffected siblings. Eight candidate neuropsychological ADHD endophenotypes with heritabilities > 0.2 were used as quantitative traits. In addition, an overall component score of neuropsychological functioning was used. A total of 5407 autosomal single-nucleotide polymorphisms (SNPs) were used to run multipoint regression-based linkage analyses. Two significant genome-wide linkage signals were found, one for Motor Timing on chromosome 2q21.1 (LOD score: 3.944) and one for Digit Span on 13q12.11 (LOD score: 3.959). Ten suggestive linkage signals were found (LOD scores > or = 2) on chromosomes 2p, 2q, 3p, 4q, 8q, 12p, 12q, 14q, and 17q. The suggestive linkage signal for the component score that was found at 2q14.3 (LOD score: 2.878) overlapped with the region significantly linked to Motor Timing. Endophenotype approaches may increase power to detect susceptibility loci in ADHD and possibly in other complex disorders.
authors.affiliation: Department of Clinical Neuropsychology, VU University Amsterdam, Amsterdam, The Netherlands.
authors.forename: Nanda N J
authors.initials: NN
authors.lastname: Rommelse
authors.forename: Alejandro
authors.initials: A
authors.lastname: Arias-Vásquez
authors.forename: Marieke E
authors.initials: ME
authors.lastname: Altink
authors.forename: Cathelijne J M
authors.initials: CJ
authors.lastname: Buschgens
authors.forename: Ellen
authors.initials: E
authors.lastname: Fliers
authors.forename: Philip
authors.initials: P
authors.lastname: Asherson
authors.forename: Stephen V
authors.initials: SV
authors.lastname: Faraone
authors.forename: Jan K
authors.initials: JK
authors.lastname: Buitelaar
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Sergeant
authors.forename: Jaap
authors.initials: J
authors.lastname: Oosterlaan
authors.forename: Barbara
authors.initials: B
authors.lastname: Franke
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000453:epidemiology / Q000235:genetics*; D016022:Case-Control Studies; D002648:Child; D002874:Chromosome Mapping; D002882:Chromosomes, Human, Pair 13; D002889:Chromosomes, Human, Pair 2; D003071:Cognition; D005260:Female; D008040:Genetic Linkage; D020022:Genetic Predisposition to Disease; D016678:Genome; D006801:Humans; D008126:Lod Score; D008297:Male; D009043:Motor Activity; D009426:Netherlands / Q000453:epidemiology; D009484:Neuropsychology; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D012044:Regression Analysis; D035781:Siblings