A novel cytochrome P-450IID6 mutant gene associated with Parkinson's disease.

Genetic polymorphism of the CYP2D6 gene [phenotypically individuals are either poor metabolizers (PM) or extensive metabolizers (EM)] has been reported to be associated with susceptibility to Parkinson's disease. We analyzed CYP2D6 genes from Japanese patients and controls, and found that EM/PM polymorphism is not a suitable marker for populations with a low PM frequency. However, a novel mutant highly associated with Parkinson's disease was discovered. The mutation was located at the HhaI site in exon 6 and changed a conserved amino acid residue, Arg296, to Cys296. The risk factor for the mutant homozygote was 5.56 (95% CI, 1.30-23.82). These results suggest that the HhaI polymorphism in the CYP2D6 gene is a part of the molecular basis of Parkinson's disease.