Association of Single-Nucleotide Polymorphisms in Interleukin Genes with Microbial Keratitis in a South Indian Population

Background: To examine the relationship between single-nucleotide polymorphisms (SNPs) in interleukin (IL) genes and keratitis and its clinical manifestations. Methods: SNPs in IL1B, IL6, CXCL8, IL10, and IL12B were analysed. Differences in frequencies of alleles, genotypes and haplotypes between cases and controls as well as associations between SNPs and clinical variables were calculated by χ2 tests with odds ratios. Results: The minor homologous genotype in IL1B rs16944 (p = 0.036; odds ratio (OR) = 2.063, 95% confidence interval (CI): 1.048–4.061) and CXCL8 rs4073 (p = 0.041; OR = 0.463, 95% CI: 0.224–0.956) and the heterologous genotypes in IL6 rs1800795 (p = 0.046; OR = 0.563, 95% CI: 0.326–0.972) and IL12B rs2569254 (p = 0.0446; OR = 0.557, 95% CI: 0.314–0.989) or rs730691 (p = 0.0051; OR = 0.451, 95% CI: 0.260–0.784) were associated with keratitis. The minor genotype of rs16944 was associated with severe infection (p = 0.046). The heterologous genotype in rs2569254 was associated with hospital admission, photophobia, and mode of contact lens wear (p ≤ 0.041). The heterologous genotype in rs730691 was associated with blurred vision, discharge, anterior chamber reaction, and mode of wear (p ≤ 0.047). Conclusions: This study demonstrates that SNPs in IL1B and CXCL8 are associated with risk of developing keratitis. The study also found relationships between SNPs and clinical measures of keratitis. The potential for ethnic differences in frequency of SNPs and their association with keratitis should be followed up using different populations.