Distribution of SDF1-3'A polymorphisms in three different ethnic groups from Brazil

A mutation described as a G-to-A transition has been reported in SDF-1 gene (SDF1-3'A), being prevalent in all ethnic groups, except in Africans. This mutation is associated with the onset of AIDS progression. Our aim was to identify the frequency of this allele in different groups from Brazil: Tiriyó and Waiampi Amerindian tribes (Asian ancestry); selected blood donors from Joinville (German descendents); and from Salvador (predominance of African and Portuguese mixture). SDF1-3'A was screened by PCR/RFLP with MspI enzyme. Our results showed a high allelic frequency in Tiriyó tribe (0.24) and Joinville population (0.21), and a frequency of 0.17 and 0.05 in the Salvador population and in the Waiampi tribe, respectively. There was no statistical difference among the allelic frequencies in the studied ethnic groups, except in the Waiampi. Due to the great genetic diversity among Brazilian population and the lack of studies on SDF1-3'A allele, our study of this allelic frequency in these different Brazilian ethnic groups could be important to identification of biomarker for therapeutic support in progression to AIDS and a molecular marker for analysis of evolutionary relationships among human populations.

Study of the CCR5-m303 mutation in three different ethnic groups from Brazil

The main coreceptor gene involved in HIV-1 infection is CCR5 beta chemokine receptor gene for which several mutations have been described, some of which have correlated with HIV-1 infection, acquired immune deficiency syndrome (AIDS), or both. Deletion of 32bp in the CCR5 gene (delta32) has been shown to confer resistance to infection by HIV-1 R5 strains. Another mutation, characterized by a thymine to adenine (T to A) nucleotide substitution at position 303 (m303), has shown the same effects as the delta32 mutation, with previous studies having shown that the allele frequency of the CCR5-m303 mutation is 0.014 in African-American and 0.007 in French populations. The Brazilian population is known to be genetically diverse, because of which we investigated the allele frequency of the CCR5-m303 mutation in three different Brazilian ethnic groups containing individuals who were not infected with HIV-1 and also in a cohort of HIV-1 long-term non-progressors. We used the polymerase chain reaction (PCR) and HincII restriction fragment length polymorphisms (RFLP) to investigate these populations and found that none of the 566 individuals examined the mutant CCR5-m303 allele. These results are in accordance with the previously reported allelic frequencies for African-American and Caucasian populations and may reflect the real prevalence of the m303 mutation in Brazil.