Though the most prominent neuropathological feature of PD is the selective loss of DA neurons in the substantia nigra (SN), immunohistochemical analysis of aged DJ-1-/- mice using an antibody specific for tyrosine hydroxylase (TH) revealed normal TH staining in the SN and normal morphology of DA neurons at the age of 24–27 months (Fig. 2C–F). Here, PARK7 is linked to Parkinson disease.