Age-dependent loss of DA neurons is a pathological feature of PD, and it was also observed in the PPL1, PPM2, and PPM3 clusters of DA neurons in dCHCHD2−/− flies (dCHCHD2−/−, mito-dR NA vs. dCHCHD2+/+, mito-dR NA in the lower graph in Fig. 4a). The gene discussed is LCMT2; the disease is Parkinson disease.