A study of ADHD in a genetic isolate
Dekker M., Van Spreeken A., Temmink A., Verhulst F., Sandkuijl L., Heutink P., Oostra B., Van Duijn C.
Attention Deficit Hyperactivity Disorder (ADHD) is thought to result from a complex interplay of genetic and environmental factors. There have been reports suggesting association of ADHD with polymorphisms in genes of the dopaminergic system. Nevertheless, the exact pathogenesis of the disorder remains unsolved. This study searches possible susceptibility genes for ADHD in a genetically isolated population. The studied population was founded by approximately 150 ancestors three centuries ago. It is characterized by little immigration and rapid expansion to a present size of 20,000 inhabitants. The aim is to detect genetic susceptibility to ADHD by means of haplotype analysis of patients who are linked to a common ancestor. Previous studies have suggested that this population is suitable for studies of genetically complex disorders such as diabetes mellitus, Alzheimer's disease and Parkinson's disease. In this population we have studied a sample of 60 ADHD-patients. The diagnosis was reviewed by a child psychiatrist according to the DSM IV-criteria. Genealogy of all patients is studied up to 15 generations ago, and preliminary results suggest a considerable number of patients can indeed be linked to a common ancestor. These patients will be included in a genomic search to assess haplotype sharing.