Mutations in the glucocerebrosidase gene, GBA, cause the autosomal recessive storage disorder Gaucher’s disease, a lysosomal storage disorder, but the observation that parkinsonism is frequently observed in this disease and in family members of Gaucher’s patients (36), in association with Lewy body deposition in the brainstem and cortex, led to the recognition of an increased frequency of heterozygote GBA mutations in PD cases versus controls. The gene discussed is GBA1; the disease is Gaucher disease.