GBA1 and Parkinson disease: Our finding may well be relevant to the penetrance of GBA1 mutations in causing Parkinson’s disease, as it is currently estimated that 10–30% of individuals with GBA1 mutations will develop Parkinson’s disease by the age of 80 (Anheim et al., 2012; Rana et al., 2013; Alcalay et al., 2014).