The motor symptoms of PD are primarily associated with the degeneration of midbrain dopaminergic neurons (DANs) in the substantia nigra compacta (SNc) [6, 7], particularly the Aldehyde Dehydrogenase 1A1-positive (ALDH1A1+) subset in its ventral tier [8–11]. The gene discussed is ALDH1A1; the disease is Parkinson disease.