RESUMO
Objective To investigate the relationship between the promoter of IL-12B gene polymorphism and the susceptibility and clinical features of chronic gastritis and duodenal ulcer with or without Helicobacter pylori(Hp) infection in children and adolescent.Methods Mucosal biopsies were obtained from 132 children and adolescent (patient group),including 100 children with chronic gastritis and 32 children with duodenal ulcer,undergoing an upper gastrointestinal endoscopy for dyspeptic symptoms.Biopsy specimens were stained with hematoxilin and eosin (HE),and gastritis was graded according to the Sydney system.Serology,urease test and histology were taken to assess Hp status.Genomic DNA was obtained from peripheral blood or gastric biopsies of patients and 102 healthy children as normal control group.The promoter of IL-12B +1188A/G gene polymorphism was genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing.The genotype distributions and allele frequencies were compared between the study group and the normal control group,and the association of genotypes with clinicopathological features was studied.IL-12B mRNA level expressions in gastric mucosa were confirmed by reverse transcription PCR biopsy-based tests.Results The genotype distributions and allele frequencies of IL-12B +1188A/G gene polymorphisms were similar in gastric upper gastrointestinal diseases and healthy subjects.The IL-12B +1188A/G gene polymorphisms were not associated with Hp status.IL-12B+1188A/G gene polymorphisms did not affect IL-12B mRNA level expressions and were not associated with the degree of antrum chronic inflammation.Conclusions These data suggest that IL-12B+1188A/G gene polymorphisms are not associated with susceptibility to chronic gastritis and duodenal ulcer in children and adolescent.