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1.  Population Genetics of GYPB and Association Study between GYPB*S/s Polymorphism and Susceptibility to P. falciparum Infection in the Brazilian Amazon 
PLoS ONE  2011;6(1):e16123.
Background
Merozoites of Plasmodium falciparum invade through several pathways using different RBC receptors. Field isolates appear to use a greater variability of these receptors than laboratory isolates. Brazilian field isolates were shown to mostly utilize glycophorin A-independent invasion pathways via glycophorin B (GPB) and/or other receptors. The Brazilian population exhibits extensive polymorphism in blood group antigens, however, no studies have been done to relate the prevalence of the antigens that function as receptors for P. falciparum and the ability of the parasite to invade. Our study aimed to establish whether variation in the GYPB*S/s alleles influences susceptibility to infection with P. falciparum in the admixed population of Brazil.
Methods
Two groups of Brazilian Amazonians from Porto Velho were studied: P. falciparum infected individuals (cases); and uninfected individuals who were born and/or have lived in the same endemic region for over ten years, were exposed to infection but have not had malaria over the study period (controls). The GPB Ss phenotype and GYPB*S/s alleles were determined by standard methods. Sixty two Ancestry Informative Markers were genotyped on each individual to estimate admixture and control its potential effect on the association between frequency of GYPB*S and malaria infection.
Results
GYPB*S is associated with host susceptibility to infection with P. falciparum; GYPB*S/GYPB*S and GYPB*S/GYPB*s were significantly more prevalent in the in the P. falciparum infected individuals than in the controls (69.87% vs. 49.75%; P<0.02). Moreover, population genetics tests applied on the GYPB exon sequencing data suggest that natural selection shaped the observed pattern of nucleotide diversity.
Conclusion
Epidemiological and evolutionary approaches suggest an important role for the GPB receptor in RBC invasion by P. falciparum in Brazilian Amazons. Moreover, an increased susceptibility to infection by this parasite is associated with the GPB S+ variant in this population.
doi:10.1371/journal.pone.0016123
PMCID: PMC3026040  PMID: 21283638
2.  A Worldwide Analysis of Beta-Defensin Copy Number Variation Suggests Recent Selection of a High-Expressing DEFB103 Gene Copy in East Asia 
Human Mutation  2011;32(7):743-750.
Beta-defensins are a family of multifunctional genes with roles in defense against pathogens, reproduction, and pigmentation. In humans, six beta-defensin genes are clustered in a repeated region which is copy-number variable (CNV) as a block, with a diploid copy number between 1 and 12. The role in host defense makes the evolutionary history of this CNV particularly interesting, because morbidity due to infectious disease is likely to have been an important selective force in human evolution, and to have varied between geographical locations. Here, we show CNV of the beta-defensin region in chimpanzees, and identify a beta-defensin block in the human lineage that contains rapidly evolving noncoding regulatory sequences. We also show that variation at one of these rapidly evolving sequences affects expression levels and cytokine responsiveness of DEFB103, a key inhibitor of influenza virus fusion at the cell surface. A worldwide analysis of beta-defensin CNV in 67 populations shows an unusually high frequency of high-DEFB103-expressing copies in East Asia, the geographical origin of historical and modern influenza epidemics, possibly as a result of selection for increased resistance to influenza in this region. Hum Mutat 32:743–750, 2011. © 2011 Wiley-Liss, Inc.
doi:10.1002/humu.21491
PMCID: PMC3263423  PMID: 21387465
CNV; defensin; antimicrobial; influenza; paralogue ratio test

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