NOD2 mutations predict the risk for surgery in pediatric-onset Crohn's disease. by Lacher, M, Helmbrecht, J, Schroepf, S, Koletzko, S, Ballauff, A, Classen, M, Uhlig, H, Hubertus, J, Hartl, D, Lohse, P, von Schweinitz, D, Kappler, R