The L-VDCC blocker, isradipine, suppresses Ca2+ influx via CaV1.3 L-VDCC and inhibits degeneration of SNc neurons (Chan et al. 2007), although this drug failed to slow the progression of PD (The Parkinson Study Group STEADY-PD III Investigators 2020). This evidence concerns the gene CACNA1D and Parkinson disease.