OBJECTIVES: Attention deficit hyperactivity disorder (ADHD) is a prevalent childhood disorder. Evidence from the family and twin studies suggest that ADHD is familiar and highly heritable. Association studies are frequently used for the searching of markers responsible for genetic basis of ADHD. We investigated TaqI polymorphism of the dopamine receptor D2 (DRD2) in relationship with ADHD. The association between TaqI A polymorphism of DRD2 gene and ADHD has previously been published. DESIGN: We used the association study to test the relationship between TaqI A polymorphism of DRD2 gene and ADHD on groups of ADHD boys and control boys. SETTING: For DNA isolation, buccal tissue was used. PCR with restriction analysis of PCR products was used for genotyping. RESULTS: We found statistically different genotypic and allelic frequencies (p < 0.008, p < 0.002, respectively) of DRD2 polymorphism between two studied groups of boys. MAIN FINDINGS: According to our results we suppose that polymorphism TaqI A of DRD2 gene is involved in the pathogenesis of childhood ADHD in male subjects. Allele A1 and genotype A1A1 in male subjects is associated with ADHD. CONCLUSIONS: Our study confirmed the relationship between TaqI A polymorphism of DRD2 gene and ADHD published previously.

Laboratory of neurobiology and molecular psychiatry Department of Biochemistry Masaryk University Faculty of Science Brno Czech Republic

A 40-bp VNTR polymorphism in the 3'-untranslated region of DAT1/SLC6A3 is associated with ADHD but not with alcoholism