In the European population HLA-class II genes are not associated with Helicobacter pylori infection

OBJECTIVE Genetic variability influences susceptibility to several diseases and depends on the specific ethnic background of individuals. HLA-class II genes have repeatedly been investigated as candidate genes for predisposition to Heliobacter pylori infection. Certain HLA-DQA1 alleles have been reported to be associated with gastric and duodenal ulcer disease in infected patients in the Japanese population. But conflicting results were reported on European and Japanese populations. METHODS HLA-DRB1 typing of 382 German individuals with well-defined H. pylori status and different clinical course of the disease was performed by polymerase chain reaction and allele-specific oligonucleotide hybridization. RESULTS No association with the infection status itself was observed in the German cohort. Similar results have been found in other European populations. In contrast, re-analysis of published data in a Japanese cohort revealed a highly significant association of DRB1*1501 with uninfected controls (P = 0.00035). In the German population, the carrier frequency of DRB1*15 was higher in H. pylori-positive individuals with gastric or duodenal ulcer but without statistical significance (gastric ulcerodds ratio, 2.13; χ = 3.77;P = 0.05; Bonferroni correction, Pc = not significant; and duodenal ulcerodds ratio, 2.15; χ = 3.4;P = 0.06;Pc = not significant). In infected individuals, autoantibodies to gastric mucosa were investigated, but no statistical significant difference in carrier frequencies of HLA-DRB1 alleles was evident. CONCLUSION The DRB1*1501–DQA1 * 01021–DQB1 * 0602 haplotype seems to provide protection from H. pylori infection in the Japanese population, whereas genetic variability in HLA-class II genes has only a minor impact on H. pylori infection and its clinical course in the European population.