GBA1 and Parkinson disease: Today, the estimated prevalence of GBA1 mutations in PD patients ranges from 5 to 25%, and their presence increases the risk for PD by up to 20 times, depending on ethnicity (Lesage et al., 2010; Beavan and Schapira, 2013; Zhao et al., 2016) despite a low penetrance (Rosenbloom et al., 2011).