1. From the Division of General Internal Medicine, Department of Medicine (A.B.), Renal Electrolyte and Hypertension Division, Department of Medicine (K.S.), Department of Genetics (K.S.), Division of Vascular Surgery, Department of Surgery (S.M.D.), University of Pennsylvania, Philadelphia; and Department of Surgery, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA (S.M.D.)