Allelic loss at SMAD4 in polyps from juvenile polyposis patients and use of fluorescence in situ hybridization to demonstrate clonal origin of the epithelium. by Woodford-Richens, K, Williamson, J, Bevan, S, Young, J, Leggett, B, Frayling, I, Thway, Y, Hodgson, S, Kim, J, Iwama, T, Novelli, M, Sheer, D, Poulsom, R, Wright, N, Houlston, R, Tomlinson, I