title: Infection by Cag A positive strains of Helicobacter pylori is associated with autoimmune thyroid disease in Iranian patients.
abstract: BACKGROUND
  Infectious agents have been suspected as a triggering factor for development of autoimmune thyroid disease (ATD). Some reports from Western countries have suggested association between Helicobacter pylori (HP) infection and ATD.
  
  
  OBJECTIVE
  To investigate the association of ATD with Cag A seropositivity in a population with high rate and early age of onset of HP infection.
  
  
  METHODS
  IgG anti HP and anti Cag A antibodies were measured in 88 patients with ATD and compared with results of 112 healthy individuals.
  
  
  RESULTS
  The rate of infection with HP was not significantly different in patient and control groups, but there was significant association between ATD and infection with Cag A strains (p<0.005). This association was significant for both hypothyroidism (p<0.005) and Graves' disease (p<0.02). Cag A antibody level correlated with titers of thyroid auto antibodies (p<0.001).
  
  
  CONCLUSIONS
  In a population with high rate and early age of onset of HP infection, only infection with Cag A positive strains is associated with ATD, and this may be due to immune cross-reactivity.
authors.affiliation: Endocrinology and Metabolism Research Center, Namazi Hospital, Shiraz, Iran, e-mail: msoveid@sums.ac.ir.
authors.forename: Mahmood
authors.initials: M
authors.lastname: Soveid
authors.forename: Kazem
authors.initials: K
authors.lastname: Hosseini Asl
authors.forename: Gholamhossein Ranjbar
authors.initials: GR
authors.lastname: Omrani
mesh_terms: D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology*; D001327:Autoimmune Diseases / Q000276:immunology* / Q000382:microbiology; D001426:Bacterial Proteins / Q000276:immunology*; D005260:Female; D006111:Graves Disease / Q000276:immunology / Q000382:microbiology; D016481:Helicobacter Infections / Q000276:immunology* / Q000382:microbiology; D016480:Helicobacter pylori / Q000276:immunology* / Q000502:physiology; D054884:Host-Pathogen Interactions / Q000276:immunology; D006801:Humans; D007037:Hypothyroidism / Q000276:immunology / Q000382:microbiology; D007074:Immunoglobulin G / Q000276:immunology; D007492:Iran; D008297:Male; D008875:Middle Aged; D013959:Thyroid Diseases / Q000276:immunology* / Q000382:microbiology; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D007074:Immunoglobulin G; C080866:cagA protein, Helicobacter pylori