Genome-wide linkage analysis in a Dutch multigenerational family with attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) is a common neuropsychiatric disorder. Genetics has an important role in the aetiology of this disease. In this study, we describe the clinical findings in a Dutch family with eight patients suffering from ADHD, in whom five had at least one other psychiatric disorder. We performed a genome-wide (parametric and nonparametric) affected-only linkage analysis. Two genomic regions on chromosomes 7 and 14 showed an excess of allele sharing among the definitely affected members of the family with suggestive LOD scores (2.1 and 2.08). Nonparametric linkage analyses (NPL) yielded a maxNPL of 2.92 (P=0.001) for marker D7S502 and a maxNPL score of 2.56 (P=0.003) for marker D14S275. We confirmed that all patients share the same haplotype in each region of 7p15.1-q31.33 and 14q11.2-q22.3. Interestingly, both loci have been reported before in Dutch (affected sib pairs) and German (extended families) ADHD linkage studies. Hopefully, the genome-wide association studies in ADHD will help to highlight specific polymorphisms and genes within the broad areas detected by our, as well as other, linkage studies.