Levels of glucosylceramide (GlcCer), one of the substrates for GBA and GBA2, and lactosylceramide (LacCer), sequential precursors of all more complex GSLs in the biosynthetic pathway, were quantified in substantia nigra from PD patients (n = 18) and age-matched controls (n = 20, provided by HBTRC) by NP-HPLC. Here, GBA2 is linked to Parkinson disease.