1. From the Bone Marrow Transplantation Program, Department of Pediatrics (W. Krivit, N.K.C.R., J.H.K.), the Division of Pediatric Neurology (E.S., W. Kennedy, M.L., L.L., S.S.), the Department of Ophthalmology (C.G.S.), and the Department of Laboratory Medicine and Pathology (M.Y.T., J.H.K.), University of Minnesota, Minneapolis; the Department of Medical Genetics (D.A.W.), Jefferson Medical College, Philadelphia; Department of Veterans Affairs (J.K.Y.), Pittsburgh; and the New England Medical Center (E.K....