Altered frequency of a promoter polymorphic allele of the kinin B1 receptor gene in inflammatory bowel disease

Background & Aims: Evidence of kinin-mediated inflammation in the gastrointestinal tract is accumulating. The genes and some polymorphic sites have been characterized for both kinin B-1 and B-2 receptors. These candidate genes were studied for their possible association with inflammatory bowel disease (IBD). Methods: In a retrospective study, the prevalence of allele pairs for four polymorphic sites of the two kinin receptor genes was determined in 53 patients with IBD and in 110 healthy volunteers similar in age, body weight, and gender proportions, using polymerase chain reaction and other techniques. Results: Only the B-1 receptor promoter polymorphism (G(-699)-->C) exhibited a significantly different allele frequency between the two groups (prevalence of the C allele of 5.7% in patients with IBD compared with 33.6% in controls; P = 0.0002) or between the controls and either etiologic subgroup (ulcerative colitis and Crohn's disease). Allelic polymorphisms affecting exon 3 of the B-1 receptor gene (A(1098)-->G) Or exon 2 (C-181-->T) or 1 (a 9-base pair deletion) of the B-2 receptor gene were found to be neutral. Conclusions: The gene corresponding to the B1 receptor for kinins may be a nonetiologic marker of symptomatic IBD, as suggested by the altered prevalence of a polymorphism presumably affecting its regulation.