Dihydrolipoamide succinyltransferase (E2, EC 2.3.1.61, chromosome 14q24.2-3) is a specific subunit of human alpha-ketoglutarate dehydrogenase complex. (KGDHC). A biallelic intragenic polymorphism was identified in E2 gene of KGDHC. It was a single nucleotide substitution between G (in allele 1) and A (in allele 2) at the position that does not change amino acid code. Using this intragenic polymorphism as a marker, we investigated the association between this gene and Parkinson's disease. Frequencies of the genotypes that carry allele 2 were significantly higher in the Parkinson's disease group than in the control group. The results indicated that a genetic variant of the E2 gene itself or in close proximity to the gene constitutes one of the genetic risk factors for Parkinson's disease.