Association of DRD4 gene polymorphism on attention deficit hyperactivity disorder : preliminary study = 한국인 주의력결핍-과잉행동장애에서 DRD4 유전자 다형성에 대한 예비적 연구

Abstract

Objective：Attention deficit hyperactivity disorder (ADHD) has a strong genetic basis, and the relationship between the allele frequency distribution and ADHD has been researched actively. We investigated the association between the DRD4 genotype and ADHD patients in Korea, in comparison with case control and family based control groups. Methods：The study enrolled 118 patients diagnosed with ADHD according to the DSM-IV diagnostic criteria and their parents (n = 70), and 84 normal children were recruited as controls. The clinical features of the patients were confirmed using the Korean versions of the Child Behavior Checklist (CBCL), Conners’ parent rating scale, Attention Deficit Diagnostic System, and Spielberger state/trait anxiety scale. Blood samples were taken from the 272 subjects. DNA was extracted from blood lymphocytes. PCR was performed to examine DRD4 polymorphisms. Allele and genotype frequencies were compared using the Chi-square test for the casecontrol analysis and the transmission disequilibrium test (TDT) for the family-based analyses. Results：In comparing the ADHD transmitted group with the not transmitted group, no significant differences were seen in the DRD4 genotype, allele distribution, or ADHD. Conclusion：However, there was a trend to an association between the DRD4 genotype, allele distribution, and ADHD for the case-control analysis. Follow-up studies with more patients or pure subgroups are needed.