PRKN and Parkinson disease: Mean fluorescence intensity analysis revealed a significant reduction of MMP for the heterozygous PRKN variant carriers (p = 0.049) as well as for the homozygous PRKN-PD patient neurons (p = 0.008), compared to the control group (1.04 ± 0.04 vs. 0.93 ± 0.03 vs. 0.85 ± 0.05) (Fig. 4f).