title: Osteopontin gene polymorphisms in Spanish patients with rheumatoid arthritis.
abstract: OBJECTIVE
  Rheumatoid arthritis (RA) is an autoimmune disease of unknown etiology characterized by cartilage and bone destruction. The main genetic determinant to RA, the shared epitope, maps to the HLA-DR locus, although this is not the only risk factor. The osteopontin (OPN) gene, with pleiotropic functions in inflammatory and immune responses, has been implicated in the pathogenesis of RA. We studied the association of polymorphisms in the OPN gene and predisposition to RA.
  
  
  METHODS
  Analysis was performed in a case-control study with 263 patients and 478 controls. Four single nucleotide polymorphisms (SNP), 327T/C, 795C/T, 1128A/G, and 1284A/C, of the OPN gene were genotyped by primer-specific amplification in the presence of SYBR Green.
  
  
  RESULTS
  Distorted transmission of these polymorphisms was studied in 58 RA trios and 61 affected sibling pairs. These SNP demonstrated strong linkage disequilibrium. No statistically significant association was observed (80% power to exclude a genotypic relative risk of 1.49 at the 5% significance level, with minor allele frequencies of 28%). This lack of association with RA was found after stratification for the shared epitope as well.
  
  
  CONCLUSIONS
  Our data suggest that, unlike the reported effect of the OPN SNP conferring predisposition to common diseases such as multiple sclerosis or systemic lupus erythematosus, these OPN gene polymorphisms do not contribute to RA susceptibility in the Spanish population we studied.
authors.affiliation: Immunology Department, Hospital Universitario San Carlos, Atencion Especializada Area 7, Martin Lagos s/n, 28040 Madrid, Spain. eurcelay@hcsc.es
authors.forename: Elena
authors.initials: E
authors.lastname: Urcelay
authors.forename: Alfonso
authors.initials: A
authors.lastname: Martínez
authors.forename: Ana
authors.initials: A
authors.lastname: Mas-Fontao
authors.forename: Alejandra
authors.initials: A
authors.lastname: Peris-Pertusa
authors.forename: Dora
authors.initials: D
authors.lastname: Pascual-Salcedo
authors.forename: Alejandro
authors.initials: A
authors.lastname: Balsa
authors.forename: Miguel
authors.initials: M
authors.lastname: Fernández-Arquero
authors.forename: Emilio
authors.initials: E
authors.lastname: de la Concha
mesh_terms: D001172:Arthritis, Rheumatoid / Q000235:genetics* / Q000276:immunology; D016022:Case-Control Studies; D000939:Epitopes; D020022:Genetic Predisposition to Disease; D006684:HLA-DR Antigens / Q000235:genetics / Q000276:immunology; D006239:Haplotypes; D006801:Humans; D053495:Osteopontin; D011110:Polymorphism, Genetic; D012307:Risk Factors; D012795:Sialoglycoproteins / Q000235:genetics*; D013030:Spain
chemical_list: D000939:Epitopes; D006684:HLA-DR Antigens; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; D053495:Osteopontin