title: Shared epitopes and rheumatoid arthritis: disease associations in Greece and meta-analysis of Mediterranean European populations.
abstract: OBJECTIVE
  To assess the strength of the associations between HLA shared epitopes (SE) and rheumatoid arthritis (RA) susceptibility, articular disease severity, and extra-articular features in Mediterranean European populations.
  
  
  METHODS
  One hundred and seventy-four Greek RA patients and 103 controls were evaluated. Data were then included in a meta-analysis of 9 studies of Mediterranean European populations (959 RA patients and 1,405 controls).
  
  
  RESULTS
  In our study population, SE alleles were significantly more common in RA patients than in controls (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.4-4.3). Larsen radiologic score was predicted by SE and disease duration. SE did not increase the risk of any extra-articular manifestation. The meta-analysis showed a pooled OR of 3.7 (95% CI, 2.6-5.2) for susceptibility to RA conferred by SE (OR, 3.4 v 3.9 in Greek v non-Greek populations).
  
  
  CONCLUSIONS
  SE determine articular destruction without increasing the risk of extra-articular manifestations. The immunogenetic associations of RA susceptibility are consistent, but their strength may depend on the SE prevalence in different ethnic groups.
authors.affiliation: Clinical and Molecular Epidemiology Unit, Department of Hygiene and Epidemiology and the Division of Rheumatology, University of Ioannina School of Medicine, Ioannina, Greece.
authors.forename: John P A
authors.initials: JP
authors.lastname: Ioannidis
authors.forename: Katerina
authors.initials: K
authors.lastname: Tarassi
authors.forename: Ioannis A
authors.initials: IA
authors.lastname: Papadopoulos
authors.forename: Paraskevi V
authors.initials: PV
authors.lastname: Voulgari
authors.forename: Kyriaki A
authors.initials: KA
authors.lastname: Boki
authors.forename: Chryssa A
authors.initials: CA
authors.lastname: Papasteriades
authors.forename: Alexandros A
authors.initials: AA
authors.lastname: Drosos
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000453:epidemiology / Q000235:genetics* / Q000503:physiopathology; D005260:Female; D020022:Genetic Predisposition to Disease; D006115:Greece / Q000453:epidemiology; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D006801:Humans; D008297:Male; D019083:Mediterranean Region / Q000453:epidemiology; D008875:Middle Aged; D012720:Severity of Illness Index
chemical_list: D000949:Histocompatibility Antigens Class II