Interferon-gamma gene polymorphism influences the frequency of a Chlamydia trachomatis cervical infection in young women.

Cervicitis associated with Chlamydia trachomatis is frequent worldwide, but the factors determining susceptibility to infection remain incompletely determined. We evaluated whether a functional single nucleotide polymorphism at position +874 in the gene coding for interferon gamma (rs2430561) influenced the likelihood of having a cervical C. trachomatis infection. This was a cross-sectional study of 142 sexually-active women attending a general gynaecology service on the outskirts of the city of Fortaleza in northeastern Brazil between August 2011 and August 2012. Endocervical swabs were evaluated for C. trachomatis DNA using hybrid capture. DNA from buccal swabs was utilised for detection of the interferon gamma 874 T/A single nucleotide polymorphism by gene amplification, endonuclease digestion and gel electrophoresis. Nineteen women (13.4%) were positive for C. trachomatis in their cervix. Positivity was 21.7% in women with the A,A genotype versus 7.0% in women with one or two T alleles (p = 0.0227). The variant T allele frequency, associated with elevated interferon gamma production, was 36.2% in women who were negative for C. trachomatis as opposed to 18.4% in women who were positive for a cervical infection with this organism (p = 0.0415). Possession of the T allele at position +874 in the gene coding for interferon gamma is associated with a reduced likelihood of a C. trachomatis cervical infection.