Infrequent Mutation of the WTl Gene 77 Wilrns ' Turnors • tn

Institut fur Humangenetik der Philipps-Universitiit, 0-35037 Marburg, Germany (M. G., A. K.), Ludwig Institute for Cancer Research and Department of Medicine, University of California at San Diego, La l olla, California 92093-0660 (K.A., W.c. ) , Cross Cancer Institute, Edmonton, Alberta, Canada (P.G. ), Division of HematologylOncology, Children's Hospital, Department of Pediatrics, Harvard Medical School and Howard Hughes Medical Institute, Boston, Massachusetts 02 11 5 (S.O.), Division of Pediatric Oncology, Dana Farber Cancer Institute and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02 115 (S.5.), Division of Urology, Department of Surgery, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02 115 (c. P., S. R. , l. M.), Dana-Farber Cancer Institute , Boston, Massachusetts 02115 (F. L.) , and Genetics Division, Children's Hospital and Dept. of Pediatrics , Harvard Medical School, Boston, Massachusetts 021 15 (0. B.); Fax: 49-93 I -888-4150