Association between TNF-alpha promoter polymorphism and Helicobacter pylori cagA subtype infection

Aims-To assess the importance of tumour necrosis factor alpha (TNF-alpha) p romoter polymorphism in relation to infection with the cytotoxin associated gene A (cagA) subtype of Helicobacter pylori within a dyspeptic Korean pop ulation. Methods-Eighty three patients with gastric disease and 113 healthy controls were studied. The DNA from gastric biopsy specimens was analysed by H pylo ri specific and cagA specific polymerase chain reaction (PCR). To character ise TNF-alpha polymorphism at positions -308 and -238, PCR based restrictio n fragment length polymorphism analysis was performed. Results-Helicobacter pylori infection was closely correlated with G to A tr ansition at position -308 of the TNF-alpha promoter when compared with heal thy controls (odds ratio (OR), 2.912; 95% confidence interval (CI), 1.082 t o 7.836; p = 0.034). Although TNF-alpha -308 polymorphism in patients with H pylori was not significantly different from that in patients without H py lori, the -308A polymorphism was strongly associated with H pylori cagA sub type infection when compared with the polymorphism in cagA negative H pylor i infection (OR, 8.757; 95% CI, 1.413 to 54.262; p = 0.019) and healthy con trols (OR, 3.683; 95% CI, 1.343 to 10.101; p = 0.011). G to A genetic chang e at position -238 of the TNF-alpha gene was not significantly associated w ith H pylori cagA subtype infection. In addition, genetic polymorphisms at both sites of the TNF-alpha promoter in patients with H pylori infection di d not correlate with the severity of disease. Conclusion-TNF-alpha -308A polymorphism was significantly related to infect ion with the H pylori cagA subtype in Korean patients with gastric disease.