A family-based association study of dopamine receptor D4 and mental retardation in Qinba region of China.

Dopamine receptor D4 (DRD4) is activated by the neurotransmitter dopamine and links to many neurological and psychiatric conditions because of its close relationship with prefrontal cortex and other important brain regions. To explore the possibility that genetic variants of DRD4 gene predispose to children with mental retardation (MR), five target SNPs of DRD4 were selected and genotyped in the samples of 163 MR pedigrees from the Qinba region of China. Two SNPs (rs752306 and rs3758653) showed weak association with MR (the P values were 0.022 and 0.015 for dominant model, and 0.027 and 0.015 for recessive model, respectively). Although they did not bear the multiple testing corrections, the haplotype which contained rs3758653 exhibited a significant association with MR (global P values were 0.018 for dominant model and 0.028 for recessive model, respectively). The in silico analysis also indicated that rs752306 and rs3758653 would be biologically meaningful SNPs. Therefore, the present study suggested that the genetic variants of DRD4 gene may play an important role in human MR. Further investigations, such as confirmation with other independent samples and functional studies, may elucidate their effect on gene expression and MR susceptibility.