Association of β-defensin 1 single nucleotide polymorphisms with Crohn's disease

Abstract

Background: It has been suggested that deficient defensin expression is connected with the chronic inflammation of Crohn's disease. The regional localization of the Crohn's disease, ileal or colonic disease can be linked to different defensin profiles. As constitutive β-defensin 1 has a colonic expression, we considered it of interest to investigate single nucleotide polymorphisms (SNPs) of the β-defensin 1 gene (DEFB1) in Crohn's disease. Methods: Three SNPs of the DEFB1 gene DEFB1 G-20A (rs11362), DEFB1 C-44G (rs1800972) and DEFB1 G-52A (rs1799946) were genotyped either by Custom TaqMan® SNP Genotyping Assays or by restriction fragment length polymorphisms (RFLP) in 190 patients with Crohn's disease and 95 Hungarian controls. Results: Strong associations between the G-20A and C-44G SNPs and the colonic, and ileocolonic localization of the disease, respectively, but no association was detected as concerns the ileal localization. A significantly higher frequency of the GA genotype of G-20A was observed among patients with colonic localization (60%) as compared with the healthy controls, (39%), with OR 2.39. The GG genotype of C-44G SNP, which can be regarded as a protective genotype, was much less frequent (4%) among the patients than among the controls (12%), OR 3.367. Conclusions: These results indicate that genetic variations in the DEFB1 gene encoding constitutive human β-defensin 1 may associated to the risk for Crohn's disease and may determine disease phenotype, e.g. colonic localization.