Strong linkage disequilibrium between HLA-B*3913 and DRB1*0807 in Brazilians.

The purpose of this research was to study the HLA-B39 distribution in 2560 healthy, unrelated, randomly selected individuals living in the southeastern region of Brazil (the states of Rio de Janeiro and São Paulo). Molecular methods were used to type HLA class I and II polymorphism: PCR-SSP, PCR-SSO, and PCR-SBT. HLA-B*39 was found in 7% (n = 182) of these individuals. HLA-B*3901, B*3906, and B*3913 were the most common alleles in this group (n = 57, 36, and 24, respectively). B*3913 was found associated with DRB1*0807 and DQB1*0402 in 16 of the 24 individuals and 13 of these were also associated with A*31012. This haplotype segregation was confirmed by family studies. Furthermore, in 5 of the 13 individuals carrying the A*31012, B*3913, DRB1*0807, and DQB1*0402 haplotype, HLA-DPB1*2701 was also present, suggesting that these alleles were found preferentially in cis association. DRB1-DPB1 linkage disequilibrium analysis was performed in 420 of the 2560 individuals and the association of DRB1*0807 with the uncommon DPB1*2701 was found to be highly significant (P <.0001). Because HLA-B*3913 and HLA-DRB1*0807 have been observed only in South American populations, it is possible that interlocus association has been selected to act on the same haplotype to collaborate in the class I and II restricted immune response to local pathogens and functional adaptation. Although numbers are small to predict which ethnic groups of the Brazilian population display this haplotype prevalently, it is possible to speculate that these data may have clinical application, such as in the selection of unrelated donors for bone marrow transplantation.

[The joint manifestations of exanthematous viroses]. / Manifestações articulares nas viroses exantemáticas.

The frequency of arthropathy was evaluated in 251 patients with clinical and serological diagnosis (specific IgM detection by enzyme immunoassay) of exanthematous disease. Arthropathy (arthralgia and/or arthritis) was more frequent in dengue fever (49%) and rubella (38.2%) cases than in human parvovirus (30%) and measles (28.1%) cases. Except for measles cases, joint complaints prevailed in adults (> or = 15 years of age) and this difference was significant. The higher frequency of arthropathy in adults was more evident in human parvovirus (75%), rubella (65%) and dengue fever (57.7%) cases than in measles cases (31%). Arthropathy was also more frequent in females for all rash diseases studied. The results of this study showed the high occurrence of joint complaints in the disease described here and the importance of laboratory confirmation for their differential diagnosis.