title: Interleukin-18 gene polymorphisms in tunisian patients with inflammatory bowel disease.
abstract: OBJECTIVE
  Interleukin (IL)-18 can regulate the Th2-mediated immune response and it may be involved in the pathogenesis of Th1 and Th2 chronic inflammatory diseases. This study sought to detect a possible association between two single nucleotide polymorphisms (SNPs) (-137G/C and -607C/A) in the IL-18 gene promoter region and susceptibility to inflammatory bowel disease (IBD) including Crohn's disease (CD) and ulcerative colitis (UC) in the Tunisian population.
  
  
  METHODS
  The (-137G/C and -607C/A) IL-18 polymorphism was analyzed in 105 patients with CD, 59 patients with UC, and 100 controls using the sequence-specific polymerase chain reaction method.
  
  
  RESULTS
  The distribution of allele and genotype frequencies illustrate that the -137G/G genotype frequency was significantly higher in UC than in controls (p value corrected (pc) = 0.038). On the other hand, we found a statistically significant association (pc = 0.033) between genotype AA of the IL-18 gene promoter (-607C/A) polymorphism in UC patients and the distal localization of the lesions. In CD, no significant differences were observed at positions -607 and -137. The analysis of IBD patients according to clinical behavior revealed no difference.
  
  
  CONCLUSIONS
  The two SNPs at position -607 (C/A) and -137 (G/C) in the promoter region of the IL-18 gene was associated with the development of UC but not CD, providing a strong support for an IBD susceptibility gene in the region surrounding IL-18. It remains to be determined precisely how the IL-18 alleles influence the pathogenesis of IBD.
authors.affiliation: Laboratory of Immunology, EPS Charles Nicolle, Tunis, Tunisia. b_a_w@hotmail.fr
authors.forename: Walid
authors.initials: W
authors.lastname: Ben Aleya
authors.forename: Imen
authors.initials: I
authors.lastname: Sfar
authors.forename: Imen
authors.initials: I
authors.lastname: Habibi
authors.forename: Leila
authors.initials: L
authors.lastname: Mouelhi
authors.forename: Houda
authors.initials: H
authors.lastname: Aouadi
authors.forename: Mouna
authors.initials: M
authors.lastname: Makhlouf
authors.forename: Salwa
authors.initials: S
authors.lastname: Ayed-Jendoubi
authors.forename: Taoufik
authors.initials: T
authors.lastname: Najjar
authors.forename: Taeib
authors.initials: T
authors.lastname: Ben Abdallah
authors.forename: Khaled
authors.initials: K
authors.lastname: Ayed
authors.forename: Yousr
authors.initials: Y
authors.lastname: Gorgi
mesh_terms: D000328:Adult; D000368:Aged; D003093:Colitis, Ulcerative / Q000235:genetics*; D003424:Crohn Disease / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D020382:Interleukin-18 / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D014416:Tunisia
chemical_list: D020382:Interleukin-18