Tyrosine hydroxylase polymorphism in familial and sporadic Parkinson's disease.

Tyrosine hydroxylase (TH) is a theoretical candidate gene determining susceptibility to Parkinson's disease (PD), and an association between one allele of a polymorphism at the TH locus and sporadic PD has been reported. We investigated TH polymorphism in 44 patients with sporadic PD, 48 patients with familial PD and 89 of their unaffected relatives, and 50 control subjects. No evidence of allelic association was detected in either familial or sporadic PD, and linkage analysis excluded the TH locus, or a closely linked gene, as a major determinant of familial PD.