Liu Y, et al. - In order to determine the family aggregation of idiopathic rapid eye movement sleep behavior disorder (iRBD), neurodegenerative diseases and related biomarkers, 404 and 387 first-degree relatives of 102 patients with iRBD and 89 controls were recruited. Among them, 204 and 208 patient relatives and controls were subjected to face-to-face clinical evaluation, while 97 and 75 relatives were subjected to further video-polysomnographic evaluation. Investigators found that iRBD is familial aggregated from isolated features to full-blown sleep disorder. Unaffected patient relatives showed a higher probability ratio of prodromal Parkinson's disease. In terms of neurodegenerative diseases and prodromal markers, relatives of patients carry a higher risk of alpha-synucleinopathy, suggesting a family aggregation and staging pathology of alpha-synucleinopathy.