title: Duffy blood group gene polymorphisms among malaria vivax patients in four areas of the Brazilian Amazon region.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors: 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. cecavasini@famerp.br
authors: Carlos E
authors: CE
authors: Cavasini
authors: Luiz C
authors: LC
authors: de Mattos
authors: Alvaro A R D'Almeida
authors: AA
authors: Couto
authors: Vanja S C D'Almeida
authors: VS
authors: Couto
authors: Yuri
authors: Y
authors: Gollino
authors: Laurence J
authors: LJ
authors: Moretti
authors: Cláudia R
authors: CR
authors: Bonini-Domingos
authors: Andréa R B
authors: AR
authors: Rossit
authors: Lilian
authors: L
authors: Castilho
authors: Ricardo L D
authors: RL
authors: Machado
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D000818:Animals; D001782:Blood Donors; D001938:Brazil / Q000453:epidemiology; D004375:Duffy Blood-Group System / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D016780:Malaria, Vivax / Q000097:blood / Q000453:epidemiology / Q000235:genetics* / Q000469:parasitology; D008297:Male; D012150:Polymorphism, Restriction Fragment Length
chemical_list: D004375:Duffy Blood-Group System