Another study demonstrated that PGRN reduction affects lysosomal metabolism by regulating glucocerebrosidase (GCase), leading to glucosylceramide (GlcCer) accumulation, which in turn promotes tau and α-synuclein aggregation, indicating that PGRN may be involved in both AD and synucleinopathies [108]. The gene discussed is MAPT; the disease is Alzheimer disease.