Contribution of Toll-Like Receptor 9 Gene Single-Nucleotide Polymorphism to Systemic Lupus Erythematosus in Egyptian Patients

Background: Systemic lupus erythematosus (SLE) is an autoimmune disease, with multiple genetic and environmental factors involved in its etiology. The toll-like receptor 9 (TLR9) gene has been reported to have important roles in the development and progression of SLE. In this case-control study, the effect of TLR9 polymorphism on susceptibility to SLE was investigated in Egyptian patients. Methods: We studied the distribution of the TLR9 rs352139 (G + 1174A) single nucleotide polymorphism (SNP) by allele-specific polymerase chain reaction (PCR) in 104 Egyptian patients with SLE and 108 age-, sex-, and ethnically matched controls. Results: There was no statistically significant difference in the distribution of the AA genotype and alleles between SLE patients and the control group in our study; however, the GA heterozygous patients were three times more likely to develop SLE (P < 0.001). A significant association was detected between TLR9 genotypes and some of the disease manifestations as myositis (p = 0.032), psychosis (p = 0.014), photosensitivity (p = 0.002), and pleurisy (p = <0.001). Moreover, we observed a significant association between the TLR9 AA and GA genotypes and the presence of antinuclear antibodies (ANA) (p = 0.038). Conclusion: The G + 1174A SNP in the toll receptor 9 gene may contribute to the genetic susceptibility of SLE in Egyptian patients. Also, an influence for this polymorphism on disease manifestations has been elucidated.