Molecular Genetics of Crohn Disease

Genetic factors play a significant role in determining inflammatory bowel disease (IBD) susceptibility. Epidemiologic data support genetic contribution to the pathogenesis of IBD, which include familial aggregation, twin studies, racial and ethnic differences in disease prevalence. Genome-wide linkage studies pointed towards more than 10 chromosomal regions and fine-mapping of these regions led to the identification of a number of genes, including CARD15 (NOD2, nucleotide oligomerization domain 2), Drosophila long disc homologue 5 gene (DLG5), OCTN1 and 2, TLR4 and CARD4 (NOD1). New genes have identified such as IL23R, immunity-related GTPase family M (IRGM), prostaglandin receptors E-serie 4 (PTGER4) and ATG16L1 for Crohn disease and ulcerative colitis. Genetic factors may influence in the clinical course of IBD patients and their likelihood of responding to certain therapies. Great progress in the understanding of the molecular genetics of IBD has been made over the last 10 years and newer genes are discovering to understand the IBD pathophysiology and to have implications for clinical practice. Key concepts Genetic factors play a significant role in determining inflammatory bowel disease susceptibility. Characterization of the IBD1 locus on chromosome 16 led to the discovery of the NOD2/CARD15 gene as the first susceptibility gene in Crohn disease. Genome-wide linkage studies pointed towards more than 10 chromosomal regions. Genetic factors may influence in the clinical course of IBD patients and their likelihood of responding to certain therapies. Keywords: genetics; IBD; molecular; CD; UC