A report of dizygous monochorionic twins.

From the Division of Medical Genetics, Department of Medicine (V.L.S.), and the Departments of Pathology (D.M.), Obstetrics and Gynecology (T.R.E., L.E.S.), and Pediatrics and Medicine (Medical Genetics) (I.A.G.), University of Washington, Seattle; the Department of Laboratories, Children’s Hospital and Regional Medical Center, Seattle (R.P.K., K.E.O.); the Genetic Epidemiology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia (D.R.N., G.W.M.); the Department of Chemistry, Seattle University, Seattle (K.S.); the Fred Hutchinson Cancer Research Center, Seattle (D.M.); and Genelex, Redmond, Wash. (C.C.T.). Address reprint requests to Dr. Souter at the Department of Obstetrics and Gynecology, Good Samaritan Regional Medical Center, 1111 E. McDowell Rd., Phoenix, AZ 85006, or at vsouter@ u.washington.edu.