GBA1 and Parkinson disease: Recently, both heterozygous and homozygous mutations in the glucocerebrosidase 1 (GBA1) gene have been linked to Parkinson’s disease, with 10–30% of individuals with GBA1 mutations developing Parkinson’s disease by the age of 80 (Anheim et al., 2012; Rana et al., 2013; Alcalay et al., 2014; Migdalska-Richards and Schapira, 2016).