GBA1 and Parkinson disease: Whereas homozygous or compound heterozygous mutations of GBA cause Gaucher disease, heterozygous GBA mutations increase the risk of developing PD and other synucleinopathies.54, 55GBA mutations are the most frequent genetic risk factor for PD identified to date, with 7% to 10% of PD patients carrying 1 of approximately 300 reported GBA mutations.54, 55