APOE and Alzheimer disease: However, the PD-associated leucine-rich repeat kinase 2 (LRRK2) mutations (31) and microtubule-associated protein tau (MAPT) H2/H1 haplotypes (32) were not associated with RBD, and neither was the AD-related Apolipoprotein E (APOE) ε4 allele (33), suggesting that the genetics of RBD only partially overlaps with PD and DLB.