APOE and Parkinson disease: GBA variants are associated with iRBD risk, PD, and DLB,5,8 but pathogenic LRRK2 variants are associated only with PD, not with iRBD and DLB.7,9,10MAPT and APOE haplotypes are important risk factors of PD and DLB, respectively,11,12 but neither is linked to iRBD.11,13 In the SNCA locus, specific variants in the 3ʹ untranslated region (UTR) are associated with PD but not with iRBD, and other, independent variants at 5ʹ UTR are associated with PD, iRBD, and DLB.14