Genotypic Identification of the Duffy Blood Group System?s Polymorphism in the Malaria Endemic Region of the Western Amazon, Brazil, Porto Velho-RO


Abstract (Summary)
The Duffy blood group antigens were first recognized as the erythrocyte receptor of chemokines and malaria parasites. Fy(a- b-) individuals resist to Plasmodium vivax infection because they lack DARC on their erythrocytes. The detention of individuals that present asymptomatic infection in regions of high endemicity for malaria, as Candelária and Bate-Estaca, Porto Velho-RO, gives indications of a possible DARC?s role in this human adaptative response. This fact led us to propose the investigation of the interactions between the Plasmodium and the Duffy system. We intend, thus, to determine the genics frequencies of the Duffy system and the distribution of mutations that condition phenotype Fy(a- b -), and to associate the genotypes investigated with morbity to the malaria. Besides, we also investigate the DARC?s role in the asymptomatic infection. The extracted DNA of leukocytes was amplified with primers FY3 and FY4 and the fragment of 661pb was digested with Ban I and Mwo I in order to identify the main genotypes of Duffy. The identification of the null genotype of Duffy occurred with primers FY1 and FY2 and digestion of fragment of 221pb with Sty I. The visualization occurred in gel of agarose 1-2% with etídio bromide and in gel of poliacrilamide 10% with nitrate of silver 10%. The level of significance adopted in the statistical analyses was 5%. The genotype most frequent of this total distribution was the FY*A/FY*B with 39% in Candelária and 30% in Bate-Estaca (109/298 individuals). The genotypics and alelics distributions are not in accordance with the conditions of Hardy-Weinberg, as much for the population in general, involving the familiar groups (?24 = 32,05, p = 0,0000), as in undersample without relationship (?24 = 15,55, p = 0,0037), and with relationship (?24 = 18,99, p = 0,0008). The aleles FY* BES and FY* BG298A possess polymorphics frequency being more frequent in mulattos. Heterozygous individuals for the alele FY* BES are susceptible to the malaria vivax and falciparum.
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Bibliographical Information:

Advisor:Vera Engracia Gama de Oliveira

School:Fundação Universidade Federal de Rondônia

School Location:Brazil

Source Type:Master's Thesis

Keywords:Genetics Susceptibility Malaria


Date of Publication:12/01/2005

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