CTSD and hyperinsulinemic hypoglycemia, familial, 4: The levels of cathepsin D, a major lysosomal enzyme involved in α-synuclein degradation (Sevlever et al., 2008) and associated with GCase deficiency (Vitner et al., 2010), was also found increased in dopaminergic neuronal cultures from GBA-N370S patients (Figure 6C).