Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia manifested by a loss of normal muscular atonia and the emergence of complex motor behaviors during REM sleep.[1] In a middle-to-older age population-based sample, the prevalence of RBD was 1.06%.[2] RBD is pathologically characterized by denaturation of alpha-synuclein, which shares the same pathological changes with neurodegenerative diseases such as Parkinson disease (PD), multiple system atrophy and Dementia with Lewy Bodies. The gene discussed is SNCA; the disease is Parkinson disease.