title: Study of the frequency of HLA-DRB1 alleles in Brazilian patients with rheumatoid arthritis.
abstract: The HLA-DRB1 alleles encoding an amino acid sequence (QKRAA/QRRAA/RRRAA) at position 70 74 of the third hypervariable region of the β1 chain of the HLA-DRB1 gene, called shared epitope (SE), are associated with increased susceptibility to and severity of rheumatoid arthritis (RA) in different populations.
  
  
  OBJECTIVE
  To determine the frequency of HLA-DRB1 alleles in Brazilian patients with RA and their association with rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPA).
  
  
  METHODS
  Four hundred and twelve patients with RA (ACR 1987) and 215 controls were included. HLA-DRB1 typing was performed by use of polymerase chain reaction (PCR) with specific primers and hybridization with sequence-specific oligonucleotide probe (SSOP). ACPA was measured by use of the ELISA technique and RF by nephelometry. The statistical analysis comprised the chi-square and Student t tests and logistic regression.
  
  
  RESULTS
  HLA-DRB1*04:01, *04:04, *04:05 alleles were associated with RA (P < 0.05); despite the wide confidence interval, it is worth noting the association between the DRB1*09:01 allele and RA (P < 0.05). HLA-DRB1 SE+ alleles were observed in 62.8% of the patients and in 31.1% of controls (OR 3.62; P < 0.001) and were associated with ACPA (OR 2.03; P < 0.001). DRB1-DERAA alleles showed a protective effect against RA (OR 0.42; P < 0.001).
  
  
  CONCLUSIONS
  In a sample of Brazilian patients with RA, most of whom of mixed heritage, HLA-DRB1 SE+ alleles were associated with susceptibility to disease and presence of ACPA.
authors.affiliation: Programa de Pós-graduação em Ciências Médicas, Universidade Estadual do Rio de Janeiro, Brasil.
authors.forename: Magali Justina Gómez
authors.initials: MJ
authors.lastname: Usnayo
authors.forename: Luis Eduardo Coelho
authors.initials: LE
authors.lastname: Andrade
authors.forename: Renata Triguenho
authors.initials: RT
authors.lastname: Alarcon
authors.forename: Juliana Cardoso
authors.initials: JC
authors.lastname: Oliveira
authors.forename: Gustavo Milson Fabrício
authors.initials: GM
authors.lastname: Silva
authors.forename: Izidro
authors.initials: I
authors.lastname: Bendet
authors.forename: Rufus
authors.initials: R
authors.lastname: Burlingame
authors.forename: Luis Cristóvão
authors.initials: LC
authors.lastname: Porto
authors.forename: Geraldo da Rocha Castelar
authors.initials: Gda R
authors.lastname: Pinheiro
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D001172:Arthritis, Rheumatoid / Q000235:genetics*; D001938:Brazil; D016022:Case-Control Studies; D005260:Female; D059811:HLA-DRB1 Chains / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D059811:HLA-DRB1 Chains