Q3 ; 246-250 ; _The strong association between HLA-B27 and spondyloarthritis (SpA) has demonstrated that typing the HLA-B27 antigen is a crucial step in diagnosis and aids in defining the progression and severity of disease.Objective_ To describe the frequency of HLA-B27 in Colombian individuals with clinical manifestations associated with SpA.Materials and Methodology_ We retrospectively analyzed 4109 HLA-B27 typing requests to the Hospital Militar Central and the Instituto de Referencia Andino from Colombian individuals with clinical signs suggestive of SpA between 2009 and 2012. We used basic digital cytometry followed by Polymerase Chain Reaction with sequence specific primers when confirmation was needed. We determined the frequency of HLA-B27 in the population and levels of association of HLA-B27 with SpA.Results_ Our population included 1585 men (36.8%) and 2524 women (61.4%). The predominant age range was between 19 and 45 years (49.9%). The majority (95.4%) of the study population came from the Andean region and eastern plains. The most frequent clinical manifestations were peripheral. Only a small fraction (12.1%) of the 4109 subjects was HLA-B27 positive. Of those, 56.9% were male, and 54.7% were between 19 and 45 years old. In contrast, when rheumatologists referred the HLA B27, 64% were found to be positive.Conclusion_ The frequency of the HLA-B27 allele in individuals with clinical signs suggestive of SpA was low, in accordance with the lower prevalence found in Colombian patients diagnosed with SpA compared to American and European population_
Ankylosing spondylitis (AS) is a common, highly heritable, inflammatory arthritis for which HLA-B*27 is the major genetic risk factor, although its role in the aetiology of AS remains elusive. To better understand the genetic basis of the MHC susceptibility loci, we genotyped 7,264 MHC SNPs in 22,647 AS cases and controls of European descent. We impute SNPs, classical HLA alleles and amino-acid residues within HLA proteins, and tested these for association to AS status. Here we show that in addition to effects due to HLA-B*27 alleles, several other HLA-B alleles also affect susceptibility. After controlling for the associated haplotypes in HLA-B, we observe independent associations with variants in the HLA-A, HLA-DPB1 and HLA-DRB1 loci. We also demonstrate that the ERAP1 SNP rs30187 association is not restricted only to carriers of HLA-B*27 but also found in HLA-B*40:01 carriers independently of HLA-B*27 genotype. ; We thank all participating subjects with AS and healthy individuals who provided the DNA and clinical information necessary for this study. This work was in part funded by grants from Arthritis Research UK (19536 and 18797), the NIHR Oxford comprehensive Biomedical Research Centre (immunity and inflammation theme A93081) and NIHR Thames Valley collaborative research network and National Ankylosing Spondylitis Society (UK). SPARCC was established through the support of the Arthritis Society of Canada. Support was received from National Institutes of Health/National Institute of Allergy and Infectious Diseases grant 1U01AI09090-01. This work was supported in part by grant PI12/02587 (Inst. Carlos III, Spain) and by European Union 'Fondos FEDER'. Support was received from Agence Nationale de la Recherche (grant ANR 2010 GEMISA and Investissements d'Avenir programme ANR-11-IDEX-0005-02), the Société Française de Rhumatologie (SFR) and the Arthritis Foundation. M.W. is funded by the Intramural Research Program, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health. M.A.B. is funded by a National Health and Medical Research Council (Australia) Senior Principal Research Fellowship. D.M.E. is funded by an Australian Research Council Future Fellowship (FT130101709). P.I.W.d.B. is funded in part by the Netherlands Organization for Scientific Research (VIDI Vernieuwingsimpuls project 016.126.354) and by the National Institutes of Health (1R01AR062886-1). ; Peer reviewed
