Toll-Like Receptor-4 Gene (Asp299Gly) polymorphism in allergic conjunctivitis

Allergic conjunctivitis (AC) is an allergic reaction that causes inflammation of the conjunctiva. Toll-like receptors (TLRs) are essential innate immune receptors that contribute to developing various allergic diseases. This case-control study aims to determine the correlation between TLR-4 gene (Asp299Gly) polymorphism and AC incidence and severity. The study included 70 AC patients and 70 non-allergic controls. All included subjects were subjected to a skin prick test, total immunoglobulin E (IgE) measurement, and TLR-4 gene (Asp299Gly) polymorphism detection by PCR restriction fragment length polymorphism (PCR-RFLP) technique. AC patients had significantly higher total IgE levels than controls (P ≤ 0.001). The frequency of the wild-type AA and heterozygous AG genotype were significantly lower in AC patients compared to controls (60 % vs. 80 % and 8.6% vs. 12.9 %, respectively). In contrast, the homozygous mutant GG genotype was significantly more prevalent among AC patients than controls (31.4 % vs. 7.1 %). Furthermore, the wild AA genotype was strongly associated with mild disease (68.2%); nonetheless, the homozygous mutant GG genotype was linked to severe disease (53.8%). The heterozygous AG genotype was only found in moderate AC patients (17.1%). AC patients with the mutant G allele may be more likely to have a severe course of AC.