ALTERED FREQUENCY OF A PROMOTER POLYMORPHIC ALLELE OF THE KININ B-1 RECEPTOR GENE IN INFLAMMATORY BOWEL-DISEASE

Background & Aims: Evidence of kinin-mediated inflammation in the gast rointestinal tract is accumulating. The genes and some polymorphic sit es have been characterized for both kinin B-1 and B-2 receptors. These candidate genes were studied for their possible association with infl ammatory bowel disease (IBD). Methods: In a retrospective study, the p revalence of allele pairs for four polymorphic sites of the two kinin receptor genes was determined in 53 patients with IBD and in 110 healt hy volunteers similar in age, body weight, and gender proportions, usi ng polymerase chain reaction and other techniques. Results: Only the B -1 receptor promoter polymorphism (G(-699)-->C) exhibited a significan tly different allele frequency between the two groups (prevalence of t he C allele of 5.7% in patients with IBD compared with 33.6% in contro ls; P = 0.0002) or between the controls and either etiologic subgroup (ulcerative colitis and Crohn's disease). Allelic polymorphisms affect ing 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 fo r kinins may be a nonetiologic marker of symptomatic IBD, as suggested by the altered prevalence of a polymorphism presumably affecting its regulation.