Association of Lewis and Secretor gene polymorphisms and Helicobacter pylori seropositivity among Japanese-Brazilians

Abstract

Background. Secretor (Se) and Lewis (Le) genes are involved in the synthesis of Lewis b (Leb) and type I antigens throughout the body, especially in the epithelial cells of gastric mucosa. Helicobacter pylori can attach to the gastric epithelial cells with the blood group antigen-binding adhesin, which binds to Leb or H type I carbohydrate structures. In a previous study, a marked association between H. pylori seropositivity and polymorphism of the Se and Le genes was observed among Japanese outpatients of a gastroenterology clinic. The present work aims to investigate the associations between Se and Le gene polymorphisms and H. pylori infection among Japanese-Brazilians. Methods. The subjects consisted of 942 healthy volunteer Japanese-Brazilians, who were tested for the presence of anti-H. pylori IgG antibodies and genotyped for Se and Le polymorphisms. Results. The sex-age-adjusted odds ratios (aORs) for H. pylori seropositivity were 0.99 for the Sese genotype relative to the SeSe genotype (95% confidence interval [CI], 0.73-1.33), and 1.03 for sese relative to SeSe (95% CI, 0.71-1.48). On the other hand, the aOR for the subjects with the le allele (Lele or lele) relative to the LeLe genotype was 1.48 (95%) CI, 1.07-1.79). When the Se and Le genotypes were analyzed in combination according to risk group, no statistically significant association was observed. Conclusions. These results are inconsistent with previous work and may have been modulated by an external factor or some other unidentified factor. Japanese-Brazilians are geno-typically the same as Japanese, but their lifestyle is adapted to that of Brazil. Further investigations are necessary to clarify this influence on susceptibility to H. pylori infection. © Springer-Verlag 2004.