Neurology 2020 08 26;95(8):e1008-e1016. Epub 2020 Jun 26.
From the Department of Human Genetics (L.K., U.R., G.A.R., Z.G.-O.), Montreal Neurological Institute (L.K., J.A.R., U.R., E.L., F.A., R.B.P., G.A.R., Z.G.-O.), and Department of Neurology and Neurosurgery (J.A.R., F.A., R.B.P., G.A.R., Z.G.-O.), McGill University, Montréal; Oxford Parkinson's Disease Centre (M.T.M.H.) and Nuffield Department of Clinical Neurosciences (M.T.M.H.), University of Oxford, UK; Sleep Disorders Unit (I.A.), Pitié Salpêtrière Hospital, Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière and Sorbonne Universities, Paris; National Reference Center for Narcolepsy, Sleep Unit (Y.D.), Department of Neurology, Gui-de-Chauliac Hospital, CHU Montpellier, University of Montpellier, Inserm U1061, France; Sleep Disorders Unit, Department of Neurology (B.H., A.S.), Medical University of Innsbruck, Austria; Department of Clinical Neurophysiology and Sleep Center (C.C.M.), University Lille North of France, CHU Lille; Sleep Disorder Unit (B.A.), Carémeau Hospital, University Hospital of Nîmes, France; Department of Biomedical and Neuromotor Sciences (DIBINEM) (G.P., E.A.), Alma Mater Studiorum, University of Bologna; IRCCS (G.P., E.A.), Istituto delle Scienze Neurologiche, Bologna; Department of Neurological Sciences (L.F.-S.), Università Vita-Salute San Raffaele, Milan, Italy; Department of Neurology with Institute of Translational Neurology (A.H.), University of Muenster, Germany; Department of Neurology (B.F.B.), Mayo Clinic, Rochester, MN; UC Gardner Neuroscience Institute and Gardner Family Center for Parkinson's Disease and Movement Disorders (A.J.E.), Cincinnati, OH; Sleep and Neurology Unit (V.C.D.C.), Beau Soleil Clinic, Montpellier; EuroMov (V.C.D.C.), University of Montpellier, France; Paracelsus-Elena-Klinik (B.M., F.S.-D., C.T.), Kassel; Department of Neurology (B.M., C.T.), University Medical Centre Goettingen; Department of Neurology (F.S.-D., W.O.), Philipps University, Marburg, Germany; Department of Neurology and Centre of Clinical Neuroscience (K.S., D.K.), Charles University, First Faculty of Medicine and General University Hospital, Prague, Czech Republic; Department of Medical Sciences and Public Health, Sleep Disorder Research Center (M.F., M.P.), University of Cagliari, Italy; Laboratory for Sleep Disorders (F.D., M.V.) and Department of Neurology (F.D., M.V.), St. Dimpna Regional Hospital, Geel, Belgium; Department of Medicine (DAME) (M.T., M.V.), University of Udine, Italy; Department of Clinical and Movement Neurosciences (M.T.), UCL Queen Square Institute of Neurology, London, UK; Clinical Neurology Unit (G.L.G., M.V.), Department of Neurosciences, University Hospital of Udine; DMIF (G.L.G.), University of Udine, Italy; Centre d'Études Avancées en Médecine du Sommeil (J.-F.G., A.D., J.Y.M., R.B.P.), Hôpital du Sacré-Cœur de Montréal; and Departments of Psychology (J.-F.G.), Neurosciences (A.D.), and Psychiatry (J.Y.M.), Université du Québec à Montréal, Canada.
Objective: To study the role of variants in the risk for isolated REM sleep behavior disorder (iRBD) and conversion to overt neurodegeneration.
Methods: A total of 4,147 individuals were included: 1,061 patients with iRBD and 3,086 controls. was fully sequenced using molecular inversion probes and Sanger sequencing. We analyzed the effects of variants on the risk of iRBD, age at onset (AAO), and conversion rates.
Results: variants were found in 9.5% of patients with iRBD compared to 4.1% of controls (odds ratio, 2.45; 95% confidence interval [CI], 1.87-3.22; = 1 × 10). The estimated OR for mild p.N370S variant carriers was 3.69 (95% CI, 1.90-7.14; = 3.5 × 10), while for severe variant carriers it was 17.55 (95% CI, 2.11-145.9; = 0.0015). Carriers of severe variants had an average AAO of 52.8 years, 7-8 years earlier than those with mild variants or noncarriers ( = 0.029). Of the variant carriers with available data, 52.5% had converted, compared to 35.6% of noncarriers ( = 0.011), with a trend for faster conversion among severe variant carriers. However, the results on AAO and conversion were based on small numbers and should be interpreted with caution.
Conclusions: variants robustly and differentially increase the risk of iRBD. The rate of conversion to neurodegeneration is also increased and may be faster among severe variant carriers, although confirmation will be required in larger samples. Screening for RBD in healthy carriers of variants should be studied as a potential way to identify variant carriers who will develop a synucleinopathy in the future.