High levels of neuronal nitric oxide synthase (nNOS) are found in the nigrostriatal regions and basal ganglia of post-mortem PD brains and animals treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a PD-inducing neurotoxin [11]. The gene discussed is NOS1; the disease is Parkinson disease.