Crohn's disease is a chronic inflammatory disorder of the gastro-intestinal tract, thought to result from the effect of environmental factors in a genetically predisposed host. In May 31
Gilles Thomas and colleagues from the Fondation Jean Dausett CEPH, Paris and Gabriel Nuñez and colleagues from the University of Michigan Medical School, both pinpointed the genetic mutation to chromosome 16. The normal gene encodes for a protein known as NOD2, which is involved in the recognition of microbes and signalling events leading to an appropriate immune response. The mutation impairs proper signalling and may result in an exaggerated inflammatory response.