The CYP2D6B allele is not overrepresented in a population of German patients with idiopathic Parkinson's disease.

The frequency of the CYP2D6B allele of the gene for debrisoquine 4-hydroxylase was studied in 115 patients with sporadic idiopathic Parkinson's disease, 55 of their healthy siblings, 63 patients with familial Parkinson's disease, 55 unaffected relatives, and 92 patients with Alzheimer's disease and 73 age matched healthy controls. By contrast with several previous studies, no significant variation of allele frequencies could be found between any of the groups studied. The results argue against a significant role of the CYP2D6 gene in the aetiology of sporadic and familial idiopathic parkinsonism in this patient population.