Associations between Polymorphisms within Interferon Gamma and Tumor Necrosis Factor Genes and Toxoplasma Retinochoroiditis in Ghanaian Patients

PURPOSE: To evaluate associations between IFN-γ +874T/A and TNF-α-308G/A polymorphism with the development of Toxoplasma retinochoroiditis. METHODS: By ARMS-PCR, a cross-sectional genetic study involving 30 patients with Toxoplasma retinochoroiditis and 87 controls was carried out. RESULTS: IFN-γ +874: by comparing with the AA genotype, individuals with the TT genotype had a 3.4 odds ratio (OR); AT had a 1.6 OR; and the T allele had a higher OR (1.6), indicating a likely susceptibility of IFN-γ +874T to the infection, though the overall distribution was not significant (p = 0.259). For TNF-α-308G/A, individuals with both GA and AA genotypes had lower ORs when compared with the GG genotype, implying the A allele could confer protection against Toxoplasma ocular lesions. CONCLUSIONS: IFN-γ +874T allele may increase the risk of ocular lesions in Toxoplasma infection. The principle of natural selection seems to also play a role. The less common TNF-308A allelic form could be protective against the development of Toxoplasma ocular infection.