Rheumatoid Arthritis: Fernandez-Arquero M

Martinez A, Salido M, Bonilla G, Pascual-Salcedo D, Fernandez-Arquero M, de Miguel S, Balsa A, de la Concha EG, Fernandez-Gutierrez B. · Hospital Clinico San Carlos, Madrid, Spain. · Arthritis Rheum. · Pubmed #15077289 links to  free full text

Abstract: OBJECTIVE: To determine whether major histocompatibility complex (MHC) polymorphisms are associated with a good or poor response to infliximab therapy in patients with rheumatoid arthritis (RA). METHODS: Seventy-eight infliximab-treated patients with RA were genotyped for HLA-DRB1, HLA-DQA1, HLA-DQB1, MHC class I chain-related gene A (MICA) transmembrane polymorphism alleles, and tumor necrosis factor a (TNFa), TNFb, TNFc, TNFd, TNFe, D6S273, HLA-B-associated transcript 2 (BAT2), and D6S2223 microsatellites. Chi-square tests were performed to compare allele proportions between responder and nonresponder patients. A control sample of 342 healthy individuals was also included to detect linkage disequilibrium between pairs of markers. RESULTS: Among responders, the frequency of the TNFa11;b4 minihaplotype was increased (41% versus 16% in nonresponders; P = 0.01) and that of the D6S273_3 allele was decreased (32% versus 56% in nonresponders; P = 0.04). The D6S273_4/BAT2_2 pair was much more frequently observed among responders (46% versus 11% in nonresponders; P = 0.001). When compared with controls, this pair of alleles was found to be associated only with the group of responder patients (46% in responders versus 17% in controls; P = 0.00002). Most of the time, these markers are present in a DRB1*0404/D6S273_4/BAT2_2/TNFa11;b4 context. No statistically significant differences were observed for MICA and D6S2223 polymorphisms and for shared epitope status. CONCLUSION: The data suggest that genetic determinants of response to infliximab therapy exist in the HLA complex.

Martinez A, Fernandez-Arquero M, Balsa A, Rubio A, Alves H, Pascual-Salcedo D, Martin-Mola E, de la Concha EG. · Hospital La Paz, Madrid, Spain. · Arthritis Rheum. · Pubmed #11407684 links to  free full text

Abstract: OBJECTIVE: To determine whether major histocompatibility complex class I chain-related gene A (MICA) polymorphisms are associated with susceptibility to rheumatoid arthritis (RA) independently of the HLA-DRB1 shared epitope (SE). METHODS: Fifty-four Spanish families with an affected son or daughter and 211 consecutive RA patients were genotyped for HLA-DRB1, tumor necrosis factor a/b microsatellite alleles, and MICA transmembrane polymorphism. We performed a case-control comparison with the consecutive patients and an independent transmission disequilibrium test with the families. RESULTS: The frequency of the MICA 6.0 allele was significantly reduced, compared with controls, in the group of SE+ patients (odds ratio 0.39, P = 0.0005). Additionally, the haplotypes containing this allele were preferentially not transmitted to the affected offspring (9 transmitted of 33; P = 0.007), independent of the presence or absence of an SE either in the same haplotype or in the other haplotype in the progenitor. CONCLUSION: These data suggest that the MICA 6.0 allele is an independent marker of protection against RA in the SE+ group of RA patients.