Interleukin 12 gene polymorphisms enhance gastric cancer risk in H pylori infected individuals

IL12, formed from p35 and p40 subunits encoded by IL12A and IL12B genes, favours T helper 1 (Th1) differentiation. Th1 lymphocytes prevail over Th2 in H pylori associated chronic gastritis, the first step in H pylori associated gastric carcinogenesis. In this study, 110 patients with non-cardia gastric cancer were compared with 251 patients with benign gastroduodenal diseases to see whether there was any correlation between IL12 gene polymorphisms and H pylori associated gastric adenocarcinoma. N Two single nucleotide polymorphisms were identified on IL12A (2504 T/G and +6686 A/G) and one on IL12B (+15485 A/G). Eleven and six alleles were found for CT and TG-TA dinucleotide repeats (VNTR) of IL12A intron 6 and IL12B intron 4, respectively. N The frequency of non-cardia gastric cancer was higher in patients with the IL12A 2504 T/T (odds ratio (OR) = 2.38) or with the IL12B VNTR (TG-TA)9/(TGTA) 11 genotype (OR = 1.36). N No IL12 gene polymorphisms were correlated with intestinal metaplasia. N These findings suggest that IL12A and IL12B gene polymorphisms may affect the final steps in gastric carcinogenesis in H pylori infected subjects.