Estudo da frequência dos alelos de HLA-DRB1 em pacientes brasileiros com artrite reumatóide

Abstract

HLA-DRB1 alleles that encode an amino acid sequence at positions 70-74 of the third hypervariable region of the B chain of the DRB1 gene, called shared epitope (SE), are associated with increased susceptibility and severity to rheumatoid arthritis (RA) in different populations. A new classification proposed by Du Montcel et al has been developed to determine the association between HLA-DRB1 and RA. This study was designer to determine the frequency of HLA-DRB1 alleles in Brazilian patients with RA, and its association with rheumatoid factor (RF), citrullinated peptide antibodies (ACPA) and radiographic joint damage and bone. Four hundred and twelve patients with RA and 215 controls were included. The HLA-DRB1 typing was performed by polymerase chain reaction (PCR) using specific primers and hybridization with sequence specific oligonucleotides (SSOP). The survey of ACPA was determined by ELISA and the RF by nephelometry, the radiographic evaluation by index method modified Sharp Van Der Heijde. For statistical analysis we used the chi-square, Student and logistic regression. In patients with rheumatoid arthritis HLA-DRB1*04:01, *04:04, *04:05 are associated with RA (p<0,05), although the wide confidence interval, it is worth noting the association observed with the DRB1*09:01 allele and the disease (p<0,05). HLA-DRB1 SE+ were observed in 62.8% of patients and in 31.1% of the control group (OR 3.62, p<0,001) and were associated with ACPA (OR 2.03, p<0,001). DERRA alleles showed a protective effect against RA (OR 0,42, p<0,001). The analysis of the new classification of HLA-DRB1 shows that S2 and S3P were associated with RA (p<0,05). Alleles S2 and/or S3P was present in 65% and 32% of patients in the control group (OR 3,86, p<0,001) and were associated with ACPA (OR 2.11, p=0,001). S3D alleles, S1, X showed a protective effect against RA. The results of this study demonstrate that Brazilian patients with RA from mostly mixed ethnicity, HLA-DRB1 evaluated under the hypothesis of the SE and the classification proposed by Du Montcel et al were associated with disease susceptibility and the presence of ACPA.