β-Globin polymorphisms in Amerindian populations from the Brazilian Amazon.
OBJECTIVE
This investigation was performed to examine genetic variation at the β-globin locus in a sample of 30 healthy individuals from native populations in South America. The patterns of haplotypic variation were compared with those of previous studies including samples for various worldwide populations in an attempt to make inferences about the occupation of the Americas from a deeper temporal perspective than is typically available with haploid markers.


METHODS
A 2.67-kb segment containing the β-globin gene and its flanking regions was examined for genetic variation in a sample of 60 chromosomes from native populations in South America. The fragment was PCR-amplified and directly sequenced. To determine linkage relationships in compound heterozygotes, we used the amplification refractory mutation system. In addition, we assessed genetic variability and differentiation among populations, and we performed tests of selective neutrality. These analyses were performed for Brazilian Amerindian group and other worldwide populations previously studied.


RESULTS
Eleven polymorphic sites were found in the studied fragment, which distinguished eight different haplotypes, three recombinants haplotypes (present as single copies) and five previously described haplotypes, including some of those most highly differentiated. Genetic variation found in the pooled sample is substantial.


CONCLUSIONS
Although only five known haplotypes are observed in Amazonia, some of these are highly divergent, resulting in patterns of molecular polymorphism equal to or higher than those from other world regions.
Laboratório de Genética Humana e Médica, Instituto de Ciências Biológicas, Universidade Federal do Pará, 66075-970 Belém, PA, Brasil. joaofg@ufpa.br
João Farias
JF
Guerreiro
Diogo
D
Meyer
Isabela Guerreiro
IG
Diniz
Andrea Ribeiro Dos
AR
Santos
Eduardo José Melo Dos
EJ
Santos
John B
JB
Clegg
D001938:Brazil / Q000208:ethnology; D002467:Cell Nucleus / Q000235:genetics; D005787:Gene Frequency; D006239:Haplotypes; D006579:Heterozygote; D006801:Humans; D007199:Indians, South American / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA; D055544:beta-Globins / Q000235:genetics*
D055544:beta-Globins