Functional haplotypes of Fc gamma (Fcγ) receptor (FcγRIIA and FcγRIIIB) predict risk to repeated episodes of severe malarial anemia and mortality in Kenyan children

Hum Genet. 2012 Feb;131(2):289-99. doi: 10.1007/s00439-011-1076-8. Epub 2011 Aug 5.

Abstract

Development of protective immunity against Plasmodium falciparum is partially mediated through binding of malaria-specific IgG to Fc gamma (γ) receptors. Variations in human FcγRIIA-H/R-131 and FcγRIIIB-NA1/NA2 affect differential binding of IgG sub-classes. Since variability in FcγR may play an important role in severe malarial anemia (SMA) pathogenesis by mediating phagocytosis of red blood cells and triggering cytokine production, the relationship between FcγRIIA-H/R131 and FcγRIIIB-NA1/NA2 haplotypes and susceptibility to SMA (Hb < 6.0 g/dL) was investigated in Kenyan children (n = 528) with acute malaria residing in a holoendemic P. falciparum transmission region. In addition, the association between carriage of the haplotypes and repeated episodes of SMA and all-cause mortality were investigated over a 3-year follow-up period. Since variability in FcγR can alter interferon (IFN)-γ production, a mediator of innate and adaptive immune responses, functional associations between the haplotypes and IFN-γ were also explored. During acute malaria, children with SMA had elevated peripheral IFN-γ levels (P = 0.006). Although multivariate logistic regression analyses (controlling for covariates) revealed no associations between the FcγR haplotypes and susceptibility to SMA during acute infection, the FcγRIIA-131H/FcγRIIIB-NA1 haplotype was associated with decreased peripheral IFN-γ (P = 0.046). Longitudinal analyses showed that carriage of the FcγRIIA-131H/FcγRIIIB-NA1 haplotype was associated with reduced risk of SMA (RR 0.65, 95% CI 0.46-0.90; P = 0.012) and all-cause mortality (P = 0.002). In contrast, carriers of the FcγRIIA-131H/FcγRIIIB-NA2 haplotype had increased susceptibility to SMA (RR 1.47, 95% CI 1.06-2.04; P = 0.020). Results here demonstrate that variation in the FcγR gene alters susceptibility to repeated episodes of SMA and mortality, as well as functional changes in IFN-γ production.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anemia / complications*
  • Anemia / genetics*
  • Child, Preschool
  • GPI-Linked Proteins / metabolism
  • Genetic Predisposition to Disease
  • Haplotypes
  • Humans
  • Infant
  • Infant, Newborn
  • Interferon-gamma / metabolism*
  • Kenya / epidemiology
  • Longitudinal Studies
  • Malaria / genetics*
  • Malaria / mortality*
  • Receptors, IgG / genetics*
  • Receptors, IgG / metabolism*
  • Recurrence

Substances

  • FCGR3B protein, human
  • Fc gamma receptor IIA
  • GPI-Linked Proteins
  • Receptors, IgG
  • Interferon-gamma