A common mitochondrial complex I ND3 gene variant, 10398G, has been reported in some studies to be associated with decreased risk of PD, and thus we also examined the PGC-1α SNPs independently and in conjunction with the A10398G ND3 SNP for an association with risk of PD or age of onset of PD. The gene discussed is MT-ND3; the disease is Parkinson disease.