GBA1 and Lewy body dementia: Genes that are important in PD such as LRRK2 and MAPT seem to have no role in iRBD,10,11 whereas other genes such as GBA are important in both, as well as in DLB.5,8 However, we cannot rule out that some of the 25 genes that we tested in the current study are associated with iRBD, yet the effect size of the association is too small to detect with the current sample size.