title: Genomewide linkage analysis identifies polymorphism in the human interferon-gamma receptor affecting Helicobacter pylori infection.
abstract: Helicobacter pylori is considered the most prevalent infectious agent among humans, and it causes gastric inflammation, gastroduodenal ulcers, and a risk of gastric cancer. We performed a genomewide linkage analysis among Senegalese siblings phenotyped for H. pylori-reactive serum immunoglobulin G. A multipoint LOD score of 3.1 was obtained at IFNGR1, the gene that encodes chain 1 of the interferon-gamma (IFN-gamma) receptor. Sequencing of IFNGR1 revealed -56C-->T, H318P, and L450P variants, which were found to be associated with high antibody concentrations. The inclusion of these in the linkage analysis raised the LOD score to 4.2. The variants were more prevalent in Africans than in whites. Our findings indicate that IFN-gamma signaling plays an essential role in human H. pylori infection, and they contribute to an explanation of the observations of high prevalences and relatively low pathogenicity of H. pylori in Africa. Moreover, they provide further support for the value of genomewide linkage studies in the analysis of susceptibility to infection and other complex genetic traits.
authors.affiliation: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Thye
authors.forename: Gerd D
authors.initials: GD
authors.lastname: Burchard
authors.forename: Manfred
authors.initials: M
authors.lastname: Nilius
authors.forename: Bertram
authors.initials: B
authors.lastname: Müller-Myhsok
authors.forename: Rolf D
authors.initials: RD
authors.lastname: Horstmann
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood*; D002896:Chromosomes, Human, Pair 6; D005787:Gene Frequency; D008040:Genetic Linkage; D005819:Genetic Markers; D014644:Genetic Variation; D015894:Genome, Human; D016481:Helicobacter Infections / Q000235:genetics* / Q000276:immunology; D016480:Helicobacter pylori / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D015810:Linkage Disequilibrium; D008126:Lod Score; D010641:Phenotype; D011110:Polymorphism, Genetic; D015995:Prevalence; D017471:Receptors, Interferon / Q000235:genetics*; D035781:Siblings; D000096743:Interferon gamma Receptor
chemical_list: D000907:Antibodies, Bacterial; D005819:Genetic Markers; D007074:Immunoglobulin G; D017471:Receptors, Interferon; D000096743:Interferon gamma Receptor