Absence of Association between the Fcγ Receptor IIIA-176F/V Polymorphism and the Severity of Malaria in Thai

Abstract

Human Fcγ receptor (Fcγ R) genes form a clustered gene family, which consists of Fcγ RIIA, IIB, IIC, IIIA, and IIIB genes, on chromosome 1q23. We previously reported that the Fcγ RIIA-131H/H genotype in combination with the Fcγ RIIIB-NA2 allele is associated with susceptibility to cerebral malaria, and that such an association can be caused by linkage disequilibrium (LD) between these polymorphisms and the primary associated gene(s) in this region. Fcγ RIIIA is known to exhibit the genetic polymorphism Fcγ RIIIA-176F/V coded for different affinity to IgG1 and IgG3. In this study, we examined a possible association between Fcγ RIIIA-176F/V polymorphism and severity of malaria in 462 adult Thai patients with Plasmodium falciparum malaria. The frequencies of Fcγ RIIIA-176V among patients with mild malaria, with non-cerebral severe malaria, and with cerebral malaria were 32.7%, 29.9%, and 36.3%, respectively. This polymorphism showed neither positive nor negative association with the severity of malaria. Thus, we concluded that the association of Fcγ RIIA-131H/R and Fcγ RIIIB-NA1/NA2 polymorphisms with cerebral malaria in Thailand is not due to the LD caused by Fcγ RIIIA-176F/V.