Multiple Genotypes of the Commonly Co-Segregating Toll-Like Receptor 4 Asp299Gly and Thr399Ile in Baluchi Malaria Patients from Iran

OBJECTIVE Different studies have shown an association of TLR4 polymorphisms with susceptibility/resistance to malaria disease. In the current immunogenetic study, we assessed the TLR4 genotypes formed by the two common single nucleotide polymorphisms (SNPs) (Asp299Gly and Thr399Ile) in the co-segregate state in Baluchi Plasmodium falciparum infected and healthy populations from malaria hypoendemic areas of Iran. The study was performed to evaluate the distribution and correlation of TLR4 co-segregating genotypes in patients with mild malaria. Moreover, the frequency of these genotypes was compared with reported results from other populations in similar or contrasting malaria settings around the world. MATERIALS AND METHODS In this case control study, the presence of 2 SNPs in the TLR4 gene (Asp299Gly and Thr399Ile) were analyzed in 350 Baluchi patients with mild malaria and 350 unrelated healthy controls by using polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) techniques followed by sequencing analysis. Differences in the TLR4 co-segregate genotype frequencies among the studied group were determined by Fisher's exact test. RESULTS Although the distribution of the two commonly co-segregating TLR4 genotypes presented a diverse and distinct pattern in the Baluchi population, no significant difference was detected between the cases and controls (p>0.05). A lower frequency of TLR4 Asp299Gly/Thr399Thr was observed in Baluchis with mild malaria compared to African populations (p< 0.05). CONCLUSION Differences in the co-segregation patterns of TLR4 Asp299Gly/Thr399Ile genotypes in the Baluchi population compared to other malaria endemic populations may suggest different local evolutionary pressure on TLR4 polymorphisms by malaria in this region. The higher frequency of Asp299Gly/Thr399Ile genotypes among the Baluchi population compared with the African population (p< 0.05) which suffers from a larger number of severe cases might suggest that this genotype has a role in protecting against severe malaria. These findings are useful for further understanding the pathogenesis of severe malaria.