Abstract
Five restriction site polymorphisms in the β-globin gene cluster (HincII-5‘ ε, HindIII-G γ, HindIII-A γ, HincII- ψβ1 and HincII-3‘ ψβ1) were analyzed in three populations (n = 114) from Reconcavo Baiano, State of Bahia, Brazil. The groups included two urban populations from the towns of Cachoeira and Maragojipe and one rural Afro-descendant population, known as the “quilombo community”, from Cachoeira municipality. The number of haplotypes found in the populations ranged from 10 to 13, which indicated higher diversity than in the parental populations. The haplotypes 2 (+ - - - -), 3 (- - - - +), 4 (- + - - +) and 6 (- + + - +) on the βA chromosomes were the most common, and two haplotypes, 9 (- + + + +) and 14 (+ + - - +), were found exclusively in the Maragojipe population. The other haplotypes (1, 5, 9, 11, 12, 13, 14 and 16) had lower frequencies. Restriction site analysis and the derived haplotypes indicated homogeneity among the populations. Thirty-two individuals with hemoglobinopathies (17 sickle cell disease, 12 HbSC disease and 3 HbCC disease) were also analyzed. The haplotype frequencies of these patients differed significantly from those of the general population. In the sickle cell disease subgroup, the predominant haplotypes were BEN (Benin) and CAR (Central African Republic), with frequencies of 52.9% and 32.4%, respectively. The high frequency of the BEN haplotype agreed with the historical origin of the afro-descendant population in the state of Bahia. However, this frequency differed from that of Salvador, the state capital, where the CAR and BEN haplotypes have similar frequencies, probably as a consequence of domestic slave trade and subsequent internal migrations to other regions of Brazil.
Highlights
For more than 20 years haplotypes from the 5’ region of the b-globin gene cluster have been used to study the origin and distribution of human populations (Wainscoat et al, 1986), as well as to trace the gene flux of variant hemoglobins HbS and HbC from Africa to other continents (Antonarakis et al, 1984; Pagnier et al, 1984).The b-globin gene cluster system has proven to be very useful in studies of the evolutionary relationships of African, Eurasian and Pacific Islander populations
In Brazil, the first study of b-globin haplotypes among patients with sickle cell anemia found the three most common haplotypes linked to the bS mutation from the African continent
The software Phase 2.1.1 identified 22 haplotypes in the b-globin cluster that had a frequency 3 1%, based on a non-recombination method. Fourteen of these haplotypes were linked to bA chromosomes, six to bS chromosomes and two to bC chromosomes
Summary
For more than 20 years haplotypes from the 5’ region of the b-globin gene cluster have been used to study the origin and distribution of human populations (Wainscoat et al, 1986), as well as to trace the gene flux of variant hemoglobins HbS and HbC from Africa to other continents (Antonarakis et al, 1984; Pagnier et al, 1984). The b-globin gene cluster system has proven to be very useful in studies of the evolutionary relationships of African, Eurasian and Pacific Islander populations. The results of these studies have supported an African origin for modern Homo sapiens and have helped to determine the major patterns of b-globin gene distribution. Of 67 chromosomes, 49 (66.2%) had the Central African Republic (CAR) haplotype, 17 (23.0%) had the Benin (BEN) haplotype and one (1.3%) had the Senegal (SEN) haplotype (Zago et al, 1992)
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