Inherited hemoglobin disorders in an Afro-Amazonian community: Saracura

Abstract

The most common hemoglobinopathies, viz, hemoglobins S and C, and α- and β-thalassemias, were investigated through the molecular screening of 116 subjects from the community of Saracura, comprising fugitive African slaves from farms of the municipality of Santarém, in the west of Pará State, Brazilian Amazon. The observed frequency of the HBB*S gene (0.9%) was significantly lower than that encountered in other Afro-derived communities in the region. Concomitantly, the absence of the HBB*C allele has been reported for most of the Afro-Amazonian communities thus far studied. As remnant populations of quilombos are generally small, the heterogeneous distribution of HBB * S and HBB * C alleles among them is probably due to genetic drift and/or founder effect. The observed frequency of 3.7 kb deletion in Saracura (8.5%) was consistent with the African origin of the population, with a certain degree of local differentiation and admixture with individuals of Caucasian ancestry, placed in evidence by the occurrence of - -(MED) deletion (1.2%), a common mutation in Mediterranean regions. As regards β-thalassemia, among the seven different mutations found in Saracura, three β o and two β + mutations were of Mediterranean origin, and two β + of African. Thus, only 28% of the local β-thalassemia mutations found in Saracura were of African origin.

Beta-Globin Haplotypes and Alpha-Thalassemia 3.7 kb Deletion in Sickle Cell Disease Patients From the Occidental Brazilian Amazon

“…Coexistence of the α-thalassemia 3.7 kb deletion with SCD promotes increase of the erythrocyte's membrane/cytoplasm ratio with reduced electrolyte loss and cellular dehydration, reduced hemolysis, increase in the concentration of hemoglobin and hematocrit, decreased erythrocyte indices (MCV and MCH) and the reticulocyte count, as shown in our sample [33,34]. The frequency of the 3.7 kb deletion of our sample of HbSS individuals does not differ from previous Brazilian studies [30,35]. Our results confirm Rumaney et al that observed an increase in the amounts of RBCs and hemoglobin and reduced MCV in SCD patients also harboring the α-thalassemia 3.7 kb deletion [36].…”

Ancestry, diversity, and genetics of health-related traits in African-derived communities (quilombos) from Brazil

“…On the other hand, α-and β-thalassemias have been studied only in the quilombo of Saracura (N) where it was reported a frequency of 9.5% for the 3.7-kb deletion for α-thalassemia (-α 3.7 ) and 1.3% of the Mediterranean deletion. β-thalassemias were detected at 8,9%, in a spectrum of seven different mutations, being only 2.1% African, and the remaining forms of Mediterranean origin (Cardoso et al 2012). The frequency of -α 3.7 is higher than the 3.3% frequency found in the urban area of Santarém, PA (Cardoso et al 2012), where the quilombo is located; however, it is similar to that observed in African-Brazilians from other urban Brazilian regions (Adorno et al 2008;Wagner et al 2010).…”

Novel Decision Tool for More Severe α-Thalassemia Genotypes Screening with Functional Loss of Two or More α-Globin Genes: A Diagnostic Test Study

“…The most frequent α-thalassemia-related mutations detected in the Brazilian population are the -α 3.7 and -α 4.2 deletions, due to the African heritage, which is very present in this population [ 5 , 7 , 9 , 10 , 33 , 34 , 35 ]. These mutations, when in heterozygosity, affect one α-gene, making this individual a silent carrier who is asymptomatic and does not need treatment.…”