GBA1 and Gaucher disease: Notably, the G-allele-associated reduction in GCase activity is similar to PD-coding risk variants that do not cause Gaucher disease (rs3115534_het versus PD_risk, P = 0.1333, β = −0.224, s.e.m. = 0.201; one-sided P value test) and higher than the Gaucher disease-causing variants (rs3115534_het versus GBA1_mild, P = 1.00 × 10−4, β = −0.846, s.e.m. = 0.215 and rs3115534_het versus GBA1_severe P = 1.52 × 10−5, β = −0.800, s.e.m. = 0.186; one-sided P value tests), confirming that the reduction in GCase is not enough to cause Gaucher disease (Fig. 5b).