Mutations in the glucocerebrosidase (
GBA) gene have emerged as a common risk factor for the development of Parkinson disease (PD). This association was originally reported in case reports and case series involving patients with Gaucher disease (GD),
1,2 an autosomal recessive lysosomal storage disease resulting from mutations in both alleles of
GBA. Gaucher disease is the most common genetic disorder in the Ashkenazi Jewish (AJ) population. Among AJ individuals, most patients with GD carry at least 1 N370S allele, a missense mutation associated with type 1 GD, the milder nonneuronopathic form. Glucocerebrosidase heterozygosity is also associated with PD based on case-control studies comparing mutation frequency in patients with PD and control participants in different ethnic groups.
1,3-10 Among patients with PD, at least 15% of AJ individuals and 3% of non-AJ individuals carry 1 of the 2 most common
GBA mutations (N370S and L444P).
7 A multicenter analysis estimated the odds ratio for carrying a
GBA mutation in patients with PD vs control participants at 5.43 (95% CI, 3.89-7.57).
7 However, data on the reverse association—the risk for PD in
GBA heterozygotes—have been limited and widely variable, with penetrance estimations between 10.9% and 29.7% by 80 years of age.
11-13 Furthermore, it is unclear whether the risk for PD is different among those carrying 2 mutant
GBA alleles (ie, patients with GD) and those with 1 mutant allele (heterozygote carriers).