Genetic factors in the etiology and potential management of inflammatory bowel disease

The inflammatory bowel diseases (IBD) are chronic inflammatory conditions affecting the intestines. Investigations into IBD have suggested that both environmental and genetic factors are involved in the pathogenesis of IBD. Based on the evidence accumulated over the last decade, current research into the etiology of IBD has been focused on the concept of an environmental stimulus affecting a genetically susceptible individual. A number of genome-wide linkage analyses using sib pairs have indicated that there are at least 4 chromosomal regions that may contain IBD susceptibility loci, designated as IBD1 (chromosome 16), IBD2 (chromosome 12), IBD3 (chromosome 6) and IBD4 (chromosome 14). Disparities in IBD linkage studies, however, are commonly encountered depending on the populations studied. One of the difficulties in genetic studies of IBD is adequate clinical classification and/or subclassification of the disease. Since IBD is a polygenic disease with complex non-Mendelian patterns of inheritance, it appears that a refined genetic disease model for IBD will be necessary before consensus among various genetic studies may be reached.