SMPD1 and Parkinson disease: This is the case for a number of LSD in the context of PD or of a parkinsonian degeneration, such as SMPD1 (sphingomyelin phosphodiesterase, Niemann–Pick disease), ATP13A2 (P5-type ATPase, Kufor–Rakeb disease), GALC (galactosylceramidase, Krabbe disease), NPC1 (Niemann–Pick type C), NAGLU (α-N-acetylglucosminidase, Sanfilippo syndrome B, or mucopoly-saccharidosis III disease B (MPS-IIIB)), HEXB (β-hexosaminidase B, Sandhoff disease (GM2 gangliosidosis)) (summarized in [114]).