HLA-DRB1 AND DQB1 ALLELES IN A BRAZILIAN POPULATION
P Louzada-Junior*, AG Smith**, JA Hansen**, EA Donadi* *Faculty of Medicine of Ribeirao Preto, University of Sao Paulo; **Fred Hutchinson Cancer Research Center, Seattle.
The modern Brazilian population represents the contribution of individuals of various racial and ethnic backgrounds, including native Amerindian populations, Caucasian immigrants from many regions of Europe and African American populations predominantly from the Niger-Congo of Equatorial Africa. Using DNA based HLA typing methods, we have analysed the DRB1 and DQB1 alleles among 161 healthy unrelated individuals comprised of Caucasian (n=86), Black (n=47) and Mullato (n=28) individuals from the Northeast region of State of São Paulo, Brazil. A total of 36 unique DRB1 alleles were detected including 8 alleles of DR4, 5 alleles of DR15/16 (02), 4 alleles each of DR8 and DR11, 3 alleles each of DR01 and DR13, 2 alleles each of DR3, 12 and 14, as well as DR7, DR9 and DR10. Common DRB1-DQB1 linkages allowed assignment of DRB1-DQB1 haplotypes in most samples. 20 DRB1 alleles were associated with a single DQB1 allele, but 16 DRB1 alleles appeared in association with 2 or more DQB1 alleles. Most diverse was DRB1*1301 found in association with DQB1*0603, 0501, 0604 and 0303. Most DRB1 alleles were detected in Caucasians, Blacks and Mullatos, but 5 DRB1 alleles were found exclusively in Caucasians, while DRB1*0406 and 1202 were identified only in Mullatos. DRB1*0302, 1503 and 0804,previously described primarily in Black populations, were found in this Brazilian population although DRB1*0302 was absent from Mullatos. Similarly, DRB1*0411, 1402 and 0807, characteristic of Native American populations were identified in this study although the latter 2 alleles were not represented among Blacks. These results illustrate the diverse racial origin of the modern Brazilian population.