MBL2Variations and Malaria Susceptibility in Indian Populations
ABSTRACTHuman mannose-binding lectin (MBL) encoded by theMBL2gene is a pattern recognition protein and has been associated with many infectious diseases, including malaria. We sought to investigate the contribution of functionalMBL2gene variations toPlasmodium falciparummalaria in well-defined cases and in matched controls. We resequenced the 8.7 kb of the entireMBL2gene in 434 individuals clinically classified with malaria from regions of India where malaria is endemic. The study cohort included 176 patients with severe malaria, 101 patients with mild malaria, and 157 ethnically matched asymptomatic individuals. In addition, 830 individuals from 32 socially, linguistically, and geographically diverse endogamous populations of India were investigated for the distribution of functionalMBL2variants. TheMBL2 −221C(X) allelic variant is associated with increased risk of malaria (mild malaria odds ratio [OR] = 1.9, correctedPvalue [PCorr] = 0.0036; severe malaria OR = 1.6,PCorr= 0.02). The exon1 variantsMBL2*B(severe malaria OR = 2.1,PCorr= 0.036; mild versus severe malaria OR = 2.5,PCorr= 0.039) andMBL2*C(mild versus severe malaria OR = 5.4,PCorr= 0.045) increased the odds of having malaria. The exon1MBL2*D/*B/*Cvariant increased the risk for severe malaria (OR = 3.4,PCorr= 0.000045). The frequencies of low MBL haplotypes were significantly higher in severe malaria (14.2%) compared to mild malaria (7.9%) and asymptomatic (3.8%). TheMBL2*LYPAhaplotypes confer protection, whereasMBL2*LXPAincreases the malaria risk. Our findings in Indian populations demonstrate thatMBL2functional variants are strongly associated with malaria and infection severity.