Given that most preclinical trials of therapeutics use methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or 6-hydroxydopamine (6-OHDA) [25], which cause specific lesions of the SNpc, our data show that in mice, the degeneration of TH-positive neurons in SNpc alone is not sufficient to reproduce the full spectrum of PD. The gene discussed is TH; the disease is Parkinson disease.