The major pathophysiologic mechanisms we addressed included: 1) dopamine transporter activity, (DAT); dopamine metabolism pathways (aldehyde dehydrogenase 1 family, member A1 gene -ALDH1 [133]) relevant to PD; and mitochondrial dysfunction due to oxidative/nitrosative stress (nitric oxide synthase 1 (neuronal) gene – nNOS) [134]. The gene discussed is SLC6A3; the disease is Parkinson disease.