title: Association of gastric cancer, HLA-DQA1, and infection with Helicobacter pylori CagA+ and VacA+ in a Mexican population.
abstract: BACKGROUND
  The goal of this study was to determine the importance of Helicobacter pylori CagA+, VacA+, and HLA-DQA1 alleles in a Mexican population with gastric cancer (GC).
  
  
  METHODS
  We studied a group of Mexican patients (cases) with distal GC (n=22) or high-grade dysplasia (HGD; n=8) (mean age, 62.7 years, F : M=0.3; age range, 33-84 years) and 77 ethnically matched non-GC controls (mean age, 47.1 years; F : M=1.96; age range, 17-92 years). Both cases and controls were H. pylori-positive by at least two of the following diagnostic tests: rapid urease test, histology, culture, or serology. The presence of antibodies to CagA and VacA proteins was determined by Western blot, and the HLA-DQA1 typing was carried out by a polymerase chain reaction (PCR) sequence-specific primer method.
  
  
  RESULTS
  The carriage of H. pylori CagA+, VacA+ strains was associated with GC or HGD (odds ratio [OR], 6.07; 95% confidence interval [CI], 1.56-27.57; P=0.005). The allele frequency of DQA1*0503 was significantly lower in the GC-HGD group than in the non-GC group (OR, 0.13; 95% CI, 0.02-0.59). Logistic regression analysis identified the carriage of HLA-DQA1*0503 as an independent protective factor for GC (OR, 0.19; 95% CI, 0.04-0.94) and colonization with H. pylori CagA+, VacA+ strains as an independent risk factor for GC (OR, 6.15; 95% CI, 1.69-22.37).
  
  
  CONCLUSIONS
  Infection with H. pylori CagA+, VacA+ strains represents a significant risk for the development of GC. The absence of HLA-DQA1*0503 could be a host risk factor for the development of GC in Mexican patients.
authors.affiliation: Departamento de Microbiología, Facultad de Medicina, Universidad Autónoma de Nuevo León, Nuevo León, Mexico.
authors.forename: Elvira
authors.initials: E
authors.lastname: Garza-González
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Bosques-Padilla
authors.forename: Guillermo I
authors.initials: GI
authors.lastname: Pérez-Pérez
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Flores-Gutiérrez
authors.forename: Rolando
authors.initials: R
authors.lastname: Tijerina-Menchaca
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000942:Antigens, Bacterial / Q000097:blood*; D001426:Bacterial Proteins / Q000097:blood*; D005260:Female; D006683:HLA-DQ Antigens / Q000032:analysis* / Q000235:genetics; D059848:HLA-DQ alpha-Chains; D016481:Helicobacter Infections / Q000097:blood* / Q000150:complications*; D016480:Helicobacter pylori; D006801:Humans; D008297:Male; D008800:Mexico; D008875:Middle Aged; D013274:Stomach Neoplasms / Q000097:blood / Q000737:chemistry* / Q000150:complications* / Q000235:genetics
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D006683:HLA-DQ Antigens; D059848:HLA-DQ alpha-Chains; C069050:HLA-DQA1 antigen; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori