There are no good studies on familial RBD forms as there are in PD, and screening of known familial PD and atypical parkinsonism genes in sporadic RBD, such as PRKN, PINK1, LRRK2, VPS35 and others, found no evidence for the involvement of any of the 10 tested genes in RBD [114]. This evidence concerns the gene LRRK2 and Parkinson disease.