GBA1 and Parkinson disease: At age 60 and 80 years, PD risks of ~5 and 9%−12% respectively are reported among GD patients, which is significantly greater than those of noncarriers (0.7 and 2.1%, respectively) but similar to the 1.5–14% and 8–19% respective prevalence among GBA heterozygote carriers (11–15), suggesting that PD risk is not further increased by carrying a second GBA mutant allele (11).