Lack of association between the dopamine transporter gene 3' VNTR polymorphism and attention deficit hyperactivity disorder in Chinese Han children: case-control and family-based studies.

Attention deficit hyperactivity disorder (ADHD) is the most common childhood onset neurodevelopment disorder. The etiology is unclear, but is suspected to involve the dopamine system. In this study we used the haplotype-based haplotype relative risk (HHRR) analysis and the transmission disequilibrium test (TDT) to investigate the potential contribution of dopamine transporter (DAT1) gene variants to ADHD. DAT1 gene polymorphisms were assessed in 54 ADHD Chinese Han children and all 108 of their parents and 66 normal child controls. No differences were found in either genotype or allele distributions. The HHRR analysis of the DAT1 polymorphisms suggests that the transmission of this polymorphism is not significantly associated with ADHD. And the TDT result showed that ADHD was not in linkage with the DAT1 gene. These findings do not support the hypothesis that DAT1 gene variants contribute to the pathogenesis of ADHD in Chinese Han population.