Association of tumor necrosis factor alpha gene polymorphisms with inflammatory bowel disease in Iran

ABSTRACT

Inflammatory bowel disease [IBD] is a chronic disease of unknown etiology, in which genetic factors, seem to play an important role in the disease predisposition and course. Assessment of tumor necrosis factor [TNF- alpha] gene polymorphisms in many populations showed a possible association with IBD. Considering the genetic variety in different ethnic groups, the aim of the present study was to investigate the association of five important single nucleotide polymorphisms [SNPs] in the promoter region of [TNF- alpha] gene with IBD in Iran. In this case-control study, 156 Ulcerative colitis [UC] patients, 50 Crohn's disease [CD] patients and 200 sex and age matched healthy controls of Iranian origin were enrolled. The study was performed during a two year period [2008-2010] at Taleghani Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran. DNA samples were evaluated for [TNF- alpha] gene polymorphisms [including -1031, -863, -857, -308 and -238] by PCR and RFLP methods. The frequency of the mutant allele of -1031 polymorphism was significantly higher in Iranian patients with Crohn's disease compared to healthy controls [P=0.01, OR=1.92; 95% CI 1.14-3.23]. None of the other evaluated polymorphisms demonstrated a significant higher frequency of mutant alleles in Iranian IBD patients compared to controls. Among the five assessed [SNPs], only -1031 polymorphism of [TNF- alpha] gene may play a role in disease susceptibility for Crohn's disease in Iran. This pattern of distribution of [TNF- alpha] gene polymorphisms could be specific in this population