Although the importance of glycoprotein Duffy in the human red cells invasion process by Plasmodium vivax merozoites has been demonstrated, little is known about the associations of FY polymorphisms with malaria vivax parasitic density. In this study, we investigated the associations of the SNPs 125 G>A, 265 C>T, and 298 G>A on FY gene and the SNP -33T>C on GATA box with the vivax malaria parasitic density in inhabitants of Amazon State, Brazil. Verifications of P. vivax, as well as the definition of parasitism, were determined by standard screening tests in 497 patients. FY phenotyping was performed in all samples by hemagglutination using gel cards. Molecular analysis for FY/GATA polymorphisms were performed by polymerase chain reaction-restriction fragment length polymorphism. Our data showed that in this population, FY*A/FY*B-33 and FY*B/FY*B-33 genotypes may be a selective advantage, reducing the frequency of P. vivax infection in the studied area. FY*A/FY*B and FY*A/FY*A genotypes showed to be associated with the rise of the frequency of P. vivax infection, and FY*B/FY*X and FY*A/FY*X showed to be associated with the low levels of parasitism. These results suggest that natural adaptations, in malaria-endemic regions, could be leading to the arising of partial defense mechanisms against P. vivax, which is different from the previously described in African descents, as well as adaptations that could be increasing the susceptibility of human to this kind of malaria.
Background The Duffy glycoprotein acts as the entry point for merozoites of Plasmodium vivax in the invasion of red blood cells. The host–parasite relationship has revealed new perspectives regarding the association between Duffy polymorphisms that can impact both the parasite density of this Plasmodium and the symptoms of this type of malaria. This study investigates the impact of Duffy polymorphisms on parasite density in patients infected with P. vivax in the Brazilian Amazon region. Methods Genotypes and Duffy polymorphism allele frequencies were compared in 287 patients with malaria, presenting low, medium and high density of P. vivax . The diagnosis of malaria was performed using a specialized team with a standardized clinical-laboratory method, while the Duffy genotyping was performed through the Bead Chip BioArray system. Both teams are reference services in Brazil. Results The FY*01 and FY*02 alleles were found in all three parasite density classes: low, medium and high, but when these alleles form genotypes with FY*02N.01 and FY*02W.01 alleles, they are found only in patients with low parasite density and low symptomatology. Another interesting finding found in this study is the presence of the genotype FY*02N.01 / FY*02W.01 in one of the patients, presenting a very low parasite density and malaria considered subclinical, a genotype which had not been previously described in the literature. Conclusion The presence of FY*02N.01 and FY*02W.01 alleles may have an impact on the reduction of clinical manifestations in malaria, leading to the development of subclinical malaria, making the infected individual an undetected natural reservoir, which may hinder the eradication of malaria in the Amazon.
Introduction: Transfusion therapy is a challenge for patients with sickle cell disease, it develops antibodies against erythrocyte antigens, especially against the Rh system antigens, more frequently against RhD antigen, as this presents allelic variations in the RHD gene, resulting in structural changes in the protein, contributing to alloimmunization these individuals. However the frequency of these variants is not known in patients with sickle cell disease in the Brazilian Amazon.Objective: In this study, our goal was to characterize the RhD variants and determine the relevance Transfusion in patients with Sickle Cell Disease in the State of Amazonas. Materials and Methods:We used 96 blood samples from patient's sickle, which were submitted to the RhD phenotype. Identification of RHD variant genotyping was performed by the microarray technique.Results: A total of 96 samples, 36 (37.5%) presented discrepant results in serology for the detection of RhD antigen, and 12 (33.3%) of these, characterized as variant RhD. Among the 12 samples molecularly characterized as variant RhD, 4 (33.33%) DF5, followed by 3 (25,00%) DIIIa, 2 (16.66%) DAU3, 1 (8.33%) DHMI, 1 (8.33%) DFV and 1 (8.33%) DAR. However, the total of 96 (100%) samples, two showed no exon 7 and the other did not show the intron 4 for multiplex PCR, however in serological tests showed normal results and the method of micro arrangements did not present RHD changes.Discussion: This study is of great importance because it is the first results of detection of RhD variants in patients with sickle cell disease state of Amazonas, since our population is differentiated from the rest of Brazil. Is important to mention, it was possible to demonstrate a higher frequency of DF5 variant in our sickle patients, this also contrasts with the world literature, since DF5 variant is more frequent in Caucasians. Conclusion:We emphasize the importance of characterization of RhD variants, in this population, as we can demonstrate significant results and that had not been described in the literature, making it clear techniques involving molecular biology increase transfusion safety and guarantee reliable results for the detection of erythrocyte antigens variants.
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