1 Department of Laboratory Medicine and Pathobiology (A.F.G., D.G.M.), University of Toronto; Division of Neurology (P.A.S., C.D.K.) and Division of Rheumatology (O.V.), Department of Medicine, St. Michael's Hospital; and Department of Laboratory Medicine (A.F.G., D.G.M.), St. Michael's Hospital, Toronto, Ontario, Canada.