Autosomal recessive mutations in GBA1, which codes for the enzyme glucocerebrosidase (GCase), are causal for the lysosomal storage disorder Gaucher’s disease, whereas heterozygous carriers are at significantly greater risk of PD (Neumann et al., 2009; Sidransky et al., 2009; Bultron et al., 2010; McNeill et al., 2012). The gene discussed is GBA1; the disease is Parkinson disease.