The dopamine d2 receptor gene is a susceptibility locus for Parkinson's disease

The dopamine D2 receptor (DRD2) gene has been proposed as a candidate gene underlying several psychiatric and neurologic disorders. The aim of the pre sent study was to examine if selected polymorphisms in the DRD2 gene are as sociated with Parkinson's disease (PD). We determined the allelic frequenci es for four polymorphisms located in the DRD2 gene in a sample of 135 patie nts with PD and 202 normal control subjects. No significant difference was observed in the allelic frequencies between patients with PD and control su bjects with regard to the -141C Ins/Del and the Ser(311)/Cys(311) variants. On the contrary, the Al allele of the TaqIA polymorphism and the B1 allele of the TaqIB polymorphism were more frequent in patients with PD than in c ontrol subjects (control subjects: TaqIA A1 = 14.6%, TaqIB B1 = 10.6% patie nts with PD: TaqIA Al = 20.7%, TaqIB B1 = 17.4%): Patients carrying the Al allele or the B1 allele had an increased risk of developing PD (TaqIA, odds ratio: 1.71, 95% confidence intervals: 1.08-2.73; TaqIB, odds ratio: 1.83, 95% confidence intervals: 1.12-3.02). The TaqIA and TaqIB polymorphisms we re in strong linkage disequilibrium, suggesting that these two polymorphism s convey the same information about the risk of presenting with PD. Genetic variation in the DRD2 gene may influence the risk of developing PD, thus c onfirming that the DRD2 gene is a susceptibility locus for PD.