Toll-Like receptor 3 genetic polymorphism in dengue encephalitis.

Abstract

Dengue is one of the important vector-borne viral diseases affecting humans with diverse manifestations. Toll-like receptors (TLR) are pattern recognition receptors and play an important role in innate immunity against microbes. TLR3 plays a critical role in controlling the innate immune response mediated by flaviviruses such as dengue. We attempted to study the susceptibility of single nucleotide polymorphism of the <i>TLR3</i> gene in dengue encephalitis (DE) patients and determine the association in terms of genotype, allele, and haplotype distribution along with the clinical outcome. It was a case-controlled observational study in a tertiary care hospital. We investigated the single nucleotide polymorphism in the <i>TLR3 Leu412Phe</i> gene using real-time polymerase chain reaction in 29 cases of DE and compared them with equal number of age- and sex-matched dengue patients without neurological features. The genotype and allele frequencies were compared using a two-sided Chi-square or Fisher's exact test. The findings revealed that the genotypic distribution of TLR3 Leu412Phe polymorphism for the mutant genotype Phe/Phe (TT) demonstrated increased association of DE (31.03% vs 6.8%, <i>P</i> 0.019, odds ratio 6.075, 95% confidence interval 1.181-31.245). However, the number of heterozygous (H) genotype (Leu/Phe-CT) and mutant Phe allele (T) did not show any statistically significant association. <i>TLR3</i> gene polymorphism did not show any correlation with mortality outcome at 1 month. The presence of mutant TLR3 Leu412Phe polymorphism may confer the propensity to have DE in patients with dengue infection in the Indian population. TLR3 polymorphism did not affect mortality outcome at 1 month.