HLA class II DNA typing in two Brazilian populations.

Brazil constitutes a melting pot of populations arising from three major groups, including Amerindians, Africans, and Europeans predominantly from Portugal who were later supplemented by migrations from other European countries. Although every possible combination of racial mixture exists in Brazil, we have selected for this study two groups of subjects residing in Rio de Janeiro. A predominant White population, among whom some Amerindian admixture may exist, and a predominantly African population having little admixture from the other races. We have used the polymerase chain reaction (PCR) and hybridization with oligonucleotide probes to perform a complete typing of the HLA class II alleles. We report the allele frequencies for HLA-DRB1, DQA1, DQB1 and DPB1. We also report on the postulated DR-DQ haplotypes based on family studies and observations in homozygous B-cell lines. These results may serve as background for various types of clinical studies in Brazilian populations.