Lack of association of IL-12 p40 gene polymorphism with peptic ulcer disease.

Interleukin 12 (IL-12) is a proinflammatory cytokine composed by two chains, p40 and p35, that plays a key role in the promotion of a Th1 immune response in the gastrointestinal mucosa. An enhanced expression of IL-12 mRNA in gastric mucosa has been reported in individuals infected by Helicobacter pylori. The aim of our study was to assess whether a functional polymorphism located at position 1188 (A-->C) of the IL-12 p40 (IL12B) gene is associated with the susceptibility and clinical features of peptic ulcer disease. Genotyping of 184 unrelated white Spanish patients with peptic ulcer and 107 healthy controls was performed by polymerase chain reaction and restriction fragment length polymorphism. Helicobacter pylori status and nonsteroidal antiinflammatory drugs use were studied in patients and controls. There were no significant differences in carriage, genotype, and allele frequencies of the IL-12 p40 gene polymorphism between patients with peptic ulcer and controls. Moreover, no differences were found with respect to the localization of the ulcer, Helicobacter pylori status, nonsteroidal antiinflammatory drug use, age, sex, bleeding episodes, and family history of peptic ulcer. Our data reveal that the IL12B 1188 (A-->C) gene polymorphism is not involved in defining the genetic basis of the susceptibility to and final outcome of peptic ulcer disease.