GBA1 and Parkinson disease: PD risk is defined by the association between specific GBA1 variants and GD phenotype: low risk, GBA1 variants that are associated with PD, but not GD (E326K, T369M); moderate/high risk, GBA1 variants that are associated with GD and PD (N370S); and unknown significance, either novel variants or those with insufficient evidence to determine pathogenicity.88