PRKN and Parkinson disease: As depicted in Fig. 4a, neurons obtained from the heterozygous variant carriers as well as from the PD patient carrying a homozygous PRKN variant, displayed MitoSox-positive mitochondria with a significantly higher mean fluorescence intensity as compared to the control neurons (0.97 ± 0.05 vs. 1.16 ± 0.05 vs. 1.22 ± 0.06; p = 0.010, p = 0.007, respectively) (Fig. 4b).