Navegando por Autor "RIBEIRO, Rita de Cassia Mousinho"

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Acesso aberto (Open Access)
Genetic relationships among native americans based on beta-globin gene cluster haplotype frequencies
(2003) RIBEIRO, Rita de Cassia Mousinho; SOUSA, Gabriella Pante de; SANTOS, Eduardo José Melo dos; GUERREIRO, João Farias
The distribution of b-globin gene haplotypes was studied in 209 Amerindians from eight tribes of the Brazilian Amazon: Asurini from Xingú, Awá-Guajá, Parakanã, Urubú-Kaapór, Zoé, Kayapó (Xikrin from the Bacajá village), Katuena, and Tiriyó. Nine different haplotypes were found, two of which (n. 11 and 13) had not been previously identified in Brazilian indigenous populations. Haplotype 2 (+ - - - -) was the most common in all groups studied, with frequencies varying from 70% to 100%, followed by haplotype 6 (- + + - +), with frequencies between 7% and 18%. The frequency distribution of the b-globin gene haplotypes in the eighteen Brazilian Amerindian populations studied to date is characterized by a reduced number of haplotypes (average of 3.5) and low levels of heterozygosity and intrapopulational differentiation, with a single clearly predominant haplotype in most tribes (haplotype 2). The Parakanã, Urubú-Kaapór, Tiriyó and Xavante tribes constitute exceptions, presenting at least four haplotypes with relatively high frequencies. The closest genetic relationships were observed between the Brazilian and the Colombian Amerindians (Wayuu, Kamsa and Inga), and, to a lesser extent, with the Huichol of Mexico. North-American Amerindians are more differentiated and clearly separated from all other tribes, except the Xavante, from Brazil, and the Mapuche, from Argentina. A restricted pool of ancestral haplotypes may explain the low diversity observed among most present-day Brazilian and Colombian Amerindian groups, while interethnic admixture could be the most important factor to explain the high number of haplotypes and high levels of diversity observed in some South-American and most North-American tribes.
Acesso aberto (Open Access)
Importância da avaliação da hemoglobina fetal na clínica da anemia falciforme
(2008-04) RIBEIRO, Rita de Cassia Mousinho; CARDOSO, Greice de Lemos; SOUSA, Ítallo Esteves Lacerda de; MARTINS, Priscila Kelly Cavalcante
Sickle cell disease is one of the commonest and most studied genetic diseases in the world. Caused by a mutation of the β gene, it changes the molecular structure of hemoglobin. Abnormal Hb S molecules suffer polymerization physiologically provoked by a low oxygen tension, acidosis and dehydration. As a result, red blood cells take on a sickle cell form, which causes microvascular occlusion with varying consequences. The objective of this study was to review the importance of fetal hemoglobin in the clinical assessment of sickle cell disease patients. It has been shown that the association of high levels of fetal hemoglobin with sickle cell disease is favorable in hematological terms. In this interaction, F cells have low Hb S concentrations and thus inhibit Hb S polymerization and the morphological alteration of red blood cells. Treatment with hydroxyurea resulting in an increased fetal hemoglobin expression brings about a significant improvement in the patient's clinical state. Thus, fetal hemoglobin constitutes the greatest inhibitor of desoxi-Hb S polymerization and avoids the morphological alteration of red blood cells, chronic hemolytic anemia, painful microvascular occlusive crises, bone infarction and necrosis of several organs thereby improving the clinical outcome and the patients' life expectancy.
Acesso aberto (Open Access)
Origin of the hemoglobin S gene in a northern Brazilian population: the combined effects of slave trade and internal migrations
(1998-12) SOUSA, Gabriella Pante de; RIBEIRO, Rita de Cassia Mousinho; SANTOS, Eduardo José Melo dos; ZAGO, Marco Antonio; GUERREIRO, João Farias
We analyzed DNA polymorphisms in the b-globin gene cluster of 30 sickle cell anemia patients from Belém, the capital city of the State of Pará, in order to investigate the origin of the bS mutation. Sixty-seven percent of the bS chromosomes were Bantu type, 30% were Benin type, and 3% were Senegal type. The origin of the bS mutation in this population, estimated on the basis of bS-linked haplotypes, contradicts the historical records of direct slave trade from Africa to the northern region of Brazil. Historical records indicate a lower percentage of people from Benin. These discrepancies are probably due to domestic slave trade and later internal migrations, mainly from northeastern to northern regions. Haplotype distribution in Belém did not differ significantly from that observed in other Brazilian regions, although historical records indicate that most slaves from Atlantic West Africa, where the Senegal haplotype is prevalent, were destined for the northern region, whereas the northeast (Bahia, Pernambuco and Maranhão) was heavily supplied with slaves from Central West Africa, where the Benin haplotype predominates.