Senkevich et al. reported that genetic modifiers such as LRRK2, endosomal/lysosomal proton channel TMEM175, α-Syn→(SNCA), and cathepsin B (CTSB) can either affect GCase activity or modulate the risk and age at the onset of GBA-associated PD [179]. Here, CTSB is linked to Parkinson disease.