Cytokine gene polymorphisms in inflammatory bowel disease.
BACKGROUND
Concordance rates in siblings and twins provide strong evidence that genetic susceptibility is important in the pathogenesis of inflammatory bowel disease. The number and identity of susceptibility genes is largely uncertain. Cytokine genes are attractive candidate loci.


OBJECTIVE
To study allelic frequencies of polymorphisms of the interleukin-1 receptor antagonist (IL-1RA) gene and the tumour necrosis factor alpha gene in patients with inflammatory bowel disease.


METHODS
One hundred and twenty nine North European caucasoid patients with ulcerative colitis, 120 patients with Crohn's disease, and 89 healthy controls.


METHODS
Genotyping was performed by polymerase chain reaction. A variable number of tandem repeats (VNTR) in the IL-1RA gene and a single base pair polymorphism in the TNF alpha gene promoter region (TNF-308) were analysed.


RESULTS
No significant differences in IL-1RA VNTR allelic frequencies were noted between Crohn's disease (allele 1: 72.6%, allele 2: 24.7%, allele 3: 2.6%), ulcerative colitis (72.6%, 24.3%, 3.1%, respectively), and controls (76.9%, 20.8% and 2.3%). Some 42.4% of patients with ulcerative colitis and 43.4% patients with Crohn's disease were carriers of allele 2, compared with 34.8% healthy subjects. The TNF2 allele was modestly reduced in Crohn's disease (13.2%), compared with healthy subjects (21.3%; p = 0.04), and ulcerative colitis (21.6%).


CONCLUSIONS
The associations demonstrated are modest: these polymorphisms are unlikely to be important determinants of overall disease susceptibility.
Louis
E
E
Gastroenterology Unit, Radcliffe Infirmary, Oxford.
Satsangi
J
J
Roussomoustakaki
M
M
Parkes
M
M
Fanning
G
G
Welsh
K
K
Jewell
D
D
D000328:Adult; D000483:Alleles; D003093:Colitis, Ulcerative / Q000276:immunology; D003424:Crohn Disease / Q000276:immunology; D016207:Cytokines / Q000235:genetics*; D004198:Disease Susceptibility; D005260:Female; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000276:immunology*; D008297:Male; D018598:Minisatellite Repeats; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors* / Q000235:genetics*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D016207:Cytokines; D017472:Receptors, Interleukin-1; D014409:Tumor Necrosis Factor-alpha