From the Dementia Research Centre (P.S.J.W., T.P., N.S.R., A.N., Y.L., K.M., I.B.M., R.L.A., H.P., J.K., M.N.R., J.M.S., N.C.F.) and MRC Prion Unit (R.D., S.M.), Department of Neurodegenerative Diseases, UCL Institute of Neurology; Department of Medical Statistics (T.P.), London School of Hygiene & Tropical Medicine, UK; and Clinical Neurochemistry Laboratory, Institute of Neuroscience and Physiology (K.B., H.Z.), the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden. (At 2017-11-21)