Alteration G2019S in the leucine-rich repeat kinase 2 gene (LRRK2) has been 
identified in several populations of patients with parkinsonism, including 
Ashkenazi Jewish subjects with Parkinson disease. Mutations in 
glucocerebrosidase (GBA), the enzyme deficient in Gaucher disease, are also 
identified at an increased frequency among Parkinson probands, including those 
of Ashkenazi Jewish ancestry. A Taqman Assay-by-Design SNP genotyping strategy 
was utilized to establish whether G2019S was found in association with GBA 
mutations. Among 37 subjects with parkinsonism who were heterozygous for a GBA 
mutation, none carried G2019S. Furthermore, G2019S was not found in 18 patients 
with Gaucher disease who developed parkinsonian manifestations and 11 other 
Gaucher probands with parkinsonism in a first degree relative. Among 45 patients 
with Gaucher disease without a history of parkinsonism, one G2019S carrier was 
found. These findings suggest that GBA and LRRK2 mutations are discrete risk 
factors for parkinsonism in both Ashkenazi Jewish and non-Jewish subjects.