In a recent cross-sectional study in China, Yuan and colleagues collected spinal CSF and serum samples from three groups of patients; iRBD, PD with RBD, and PD without RBD, in order to investigate the association between orexin and tumour necrosis factor alpha (TNF-alpha) levels with motor, sleep, and cognitive symptoms [56]. The gene discussed is HCRT; the disease is Parkinson disease.