A susceptibility gene for Parkinson's disease (PD) with late onset and typical Lewy-body pathology maps to chromosome 2p13 (PARK3). In the present study we examined the gene for transforming growth factor alpha (TGF alpha), which is located in the PARK3-region, as a potential candidate gene. This polypeptide mitogen exerts trophic actions on dopaminergic neurons and TGF alpha-deficient mice have fewer dopaminergic neurons. We did not find mutations in the exonic or exon-flanking intronic sequences of index patients of two families linked to 2p13. This result excludes mutations in the coding region of TGF alpha as a cause for hereditary PD, but does not rule out a possible role of sequence variants in regulatory regions or splice sites.