Post hoc analysis revealed that median serum levels of Parkin were more elevated in controls (132.8 pg/ml) and VAD (125.9 pg/ml) as compared to AD (62.13 pg/ml), MCI (59.89 pg/ml), and MD (60.80 pg/ml) (all p < 0.01) (Fig. 1, Panel B). Here, PRKN is linked to Alzheimer disease.