Genetic factors associated with the development of inflammatory bowel disease.

Crohn's disease (CD) and ulcerative colitis (UC) are complex polygenic disorders, characterized by several genes together with environmental factors contributing to the development of inflammatory bowel disease (IBD). Recent advances in research on genetic susceptibility have allowed the identification of diverse genes at different levels: (1) Innate immunity; (2) Antigen presentation molecules; (3) Epithelial integrity; (4) Drug transporter; (5) Cell adhesion. The application of genetic testing into clinical practice is close and all genetic markers may have several clinical implications: prediction of disease phenotype, molecular classification, prevention of complications, and prognosis.