[1] Univ Penn, Dept Med, Div Gastroenterol, Philadelphia, PA 19104 USA
[2] Univ Penn, Dept Genet, Philadelphia, PA 19104 USA
[3] Univ Penn, Abramson Canc Ctr, Philadelphia, PA 19104 USA
[4] Vanderbilt Univ, Dept Surg, Nashville, TN 37232 USA
[5] Vanderbilt Univ, Dept Cell & Dev Biol, Nashville, TN 37232 USA
[6] Johns Hopkins Univ, McKusick Nathans Inst Genet Med, Dept Surg, Baltimore, MD 21205 USA
[7] Johns Hopkins Univ, McKusick Nathans Inst Genet Med, Dept Oncol, Baltimore, MD 21205 USA
[8] Johns Hopkins Univ, McKusick Nathans Inst Genet Med, Dept Cell Biol, Baltimore, MD 21205 USA