Aim: To investigate the possible association between TNF-alpha (-308G/A) polymorphism and toxoplasmic retinochoroiditis (TR) in humans.
Methods: A cross-sectional study was performed which included 100 Brazilian patients with diagnosis of TR and 100 matched control subjects with positive serology to toxoplasmosis and no sign of uveitis. Genomic DNA was obtained from oral swabs of all subjects and amplified using the polymerase chain reaction (PCR) with specific primers flanking the locus -308 of TNF-alpha. PCR products were submitted to restriction endonuclease digestion and analysed by polyacrylamide gel electrophoresis to distinguish alleles, allowing the determination of the genotypes.
Results: There was no significant difference in the genotype (chi(2) = 0.79, p = 0.67), allele (chi(2) = 0.095, p = 0.75) and allele carriage (chi(2) = 0.70, p = 0.40) frequencies in TR patients compared with control subjects. Frequencies of the genotype (chi(2) = 2.05, p = 0.35) and allele (chi(2) = 0.13, p = 0.71) did not differ significantly between TR patients with and without recurrent episodes.
Conclusion: This is the first study to investigate the association between TNF-alpha polymorphism and the occurrence of TR in humans. TNF-alpha gene polymorphism (-308G/A) does not seem to be associated with the occurrence or recurrence of TR.