Research
Duffy blood group gene polymorphisms among malaria vivax patients in four areas of the Brazilian Amazon region
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* Corresponding author: Carlos E Cavasini cecavasini@famerp.br
1 Centro de Investigação de Microrganismos, Faculdade de Medicina de São José do Rio Preto. Av. Brigadeiro Faria Lima, 5416. São José do Rio Preto, São Paulo State 15090-000, Brazil
2 Imunogenetics Laboratory, Department of Molecular Biology, Faculty of Medicine from São José do Rio Preto, São José do Rio Preto, São Paulo State, Brazil
3 SEAMA Faculty, Macapá, Amapá State, Brazil
4 Evandro Chagas Institute, Malaria Program, Belém, Pará Sate, Brazil
5 Hemoglobin Diseases Laboratory, IBILCE/UNESP, São José do Rio Preto, São Paulo State, Brazil
6 Blood Bank, Campinas University, Campinas, São Paulo State, Brazil
Malaria Journal 2007, 6:167 doi:10.1186/1475-2875-6-167
Published: 19 December 2007Abstract
Background
Duffy blood group polymorphisms are important in areas where Plasmodium vivax predominates, because this molecule acts as a receptor for this protozoan. In the present study, Duffy blood group genotyping in P. vivax malaria patients from four different Brazilian endemic areas is reported, exploring significant associations between blood group variants and susceptibility or resistance to malaria.
Methods
The P. vivax identification was determined by non-genotypic and genotypic screening tests. The Duffy blood group was genotyped by PCR/RFLP in 330 blood donors and 312 malaria patients from four Brazilian Amazon areas. In order to assess the variables significance and to obtain independence among the proportions, the Fisher's exact test was used.
Results
The data show a high frequency of the FYA/FYB genotype, followed by FYB/FYB, FYA/FYA, FYA/FYB-33 and FYB/FYB-33. Low frequencies were detected for the FYA/FYX, FYB/FYX, FYX/FYX and FYB-33/FYB-33 genotypes. Negative Duffy genotype (FYB-33/FYB-33) was found in both groups: individuals infected and non-infected (blood donors). No individual carried the FYX/FYB-33 genotype. Some of the Duffy genotypes frequencies showed significant differences between donors and malaria patients.
Conclusion
The obtained data suggest that individuals with the FYA/FYB genotype have higher susceptibility to malaria. The presence of the FYB-33 allele may be a selective advantage in the population, reducing the rate of infection by P. vivax in this region. Additional efforts may contribute to better elucidate the physiopathologic differences in this parasite/host relationship in regions endemic for P. vivax malaria, in particular the Brazilian Amazon region.