The importance of the polymorphisms of the ABCB1 gene in disease susceptibility, behavior and response to treatment in inflammatory bowel disease: A literature review.

Abstract

Crohn's disease (CD) and ulcerative colitis (UD) are the 2 common clinical subtypes of idiopathic inflammatory bowel disease (IBD) characterized by chronic inflammation of the gastrointestinal tract. The multifactorial etiology and pathogenesis of IBD is still unknown; however, the interaction between genetic, environmental and immunological factors seems to be crucial. A member of the adenosine triphosphate (ATP)-binding cassette family, P-glycoprotein, encoded by the human ABCB1 gene, is among the most extensively studied transporters involved in drug disposition and effects. Single nucleotide polymorphisms (SNPs) located in exons 21, 26 and 12, i.e., G2677T/A, C3435T and C1236T, are of the greatest clinical importance. Functional defects of the intestinal epithelial barrier due to the lack of P-glycoprotein expression may constitute possible reasons for the development of colitis. Given that several drugs central to the therapy of IBD are also P-glycoprotein substrates, it has been hypothesized that its altered expression in IBD patients could modify the response to medical treatment. Nevertheless, there are conflicting reports of an association between these 3 SNPs and IBD. This article aims to review all relevant studies investigating the role of the polymorphisms of the ABCB1 gene in disease susceptibility, behavior and response to treatment in IBD.