Variations in host genes encoding adhesion molecules and susceptibility to falciparum malaria in India

Abstract

Background: Host adhesion molecules play a significant role in the pathogenesis ofPlasmodium falciparummalaria and changes in their structure or levels in individuals can influence the outcome of infection. The aim of this study was to investigate the association of SNPs of three adhesion molecule genes,ICAM1,PECAM1andCD36, with severity of falciparum malaria in a malaria-endemic and a non-endemic region of India.Methods: The frequency distribution of seven selected SNPs ofICAM1,PECAM1andCD36was determined in 552 individuals drawn from 24 populations across India. SNP-disease association was analysed in a case-control study format. Genotyping of the population panel was performed by Sequenom mass spectroscopy and patient/control samples were genotyped by SNaPshot method. Haplotypes and linkage disequilibrium (LD) plots were generated using PHASE and Haploview, respectively. Odds-ratio (OR) for risk assessment was estimated using EpiInfo™ version 3.4.Results: Association of the ICAM1 rs5498 (exon 6) G allele and the CD36 exon 1a A allele with increased risk of severe malaria was observed (severe versus control, OR = 1.91 and 2.66, P = 0.02 and 0.0012, respectively). The CD36 rs1334512 (-53) T allele as well as the TT genotype associated with protection from severe disease (severe versus control, TT versus GG, OR = 0.37, P = 0.004). Interestingly, a SNP of thePECAM1gene (rs668, exon 3, C/G) with low minor allele frequency in populations of the endemic region compared to the non-endemic region exhibited differential association with disease in these regions; the G allele was a risk factor for malaria in the endemic region, but exhibited significant association with protection from disease in the non-endemic region.Conclusion: The data highlights the significance of variations in theICAM1,PECAM1andCD36genes in the manifestation of falciparum malaria in India. ThePECAM1exon 3 SNP exhibits altered association with disease in the endemic and non-endemic region.