CYP2D6 POLYMORPHISM IS NOT ASSOCIATED WITH ESSENTIAL TREMOR

Recent reports have shown an association between cytochrome P450IID6 ( CYP2D6) polymorphism and Parkinson's disease. We investigated the asso ciation between this polymorphism and the risk for developing essentia l tremor (ET). Leukocytic DNA from 91 unrelated ET patients and a cont rol group of 258 unrelated healthy individuals was studied for the occ urrence of eight different CYP2D6 allelic variants by using allele-spe cific PCR amplification XbaI and EcoRI-RFLP's analyses. The prevalence for these allelic variants in the ET and control groups were, respect ively: CYP2D61 76.9 and 78.7%, CYP2D6*2 0.5 and 0.2%, CYP2D6*3 0 and 1%, CYP2D64 12.1 and 12.2%, CYP2D6*5 1.6 and 1.7%, CYP2D6*9 4.4 and 2 .9%, CYP2D62x2 4.4 and 3.2%. The prevalence of subjects with absent C YP2D6 activity (those carrying two defect genes) was 1.1 and 3.1% in E T and control groups, respectively. Both groups studied were in Hardy- Weinberg equilibrium. These results indicate that mutations at the CYP 2D6 gene do not seem to be a major factor in determining susceptibilit y to ET, and reinforces the view that ET and parkinsonism are distinct conditions.