CACNA1D and Parkinson disease: Dopaminergic neurons of the SNpc are uniquely susceptible to perturbations that lead to the development of PD, when compared to dopaminergic neurons of the ventral tegmental area (VTA), which has been shown due to the dependence of SNpc neurons on Cav1.3 for their rhythmicity (Chan et al., 2007; Surmeier, 2007; Chan et al., 2009; Fu et al., 2018).