Gene and genotype frequencies for HLA-DQA1 in Caucasians and Mulattoes in Brazil.

Gene and genotype frequencies of the HLA-DQA1 locus were determined in a sample of 197 unrelated individuals (144 Caucasians and 53 Mulattoes), living in the city of São Paulo, Brazil. The Mulatto group consisted of mixed individuals who presented at least one negroid physical characteristic or declared themselves to be of mixed ancestry. A total of six different alleles were identified with frequencies ranging from 0.087 to 0.316 in the Caucasian population and from 0.066 to 0.330 in the Mulatto population. We observed an increased frequency of allele 1.2 among Mulattoes in relation to Caucasians. The sample heterozygote frequency was 0.722 among Caucasians and 0.736 among Mullatoes. No significant deviations from Hardy-Weinberg equilibrium were found either in the Caucasian or in the Brazilian Mullato population samples.