Although the majority of the adult mDA neurons co-express PITX3, point mutations causing a loss-of-function in aphakia (ak) and eyeless (eyl) mice, or inactivation of this gene in Pitx3−/− mice, primarily affected the vSNc DA subset, whereas the dSNc and VTA DA subpopulations were relatively spared in these mutant mice [(Li et al., 2009; Tran and Kioussi, 2021) and references therein; (Rosemann et al., 2009; Luk et al., 2013; Le et al., 2015)]. The gene discussed is PITX3; the disease is congenital primary aphakia.