In the mouse, targeted Lmx1a/Lmx1b ablation triggered mDAN decline associated with neuropathological (e.g., α-synuclein–positive, distended axonal terminals) and behavioral abnormalities consistent with PD (Doucet-Beaupre et al., 2016; Laguna et al., 2015). The gene discussed is LMX1A; the disease is Parkinson disease.