Association of the interferon-γ gene (CA)n repeat polymorphism with endometriosis

Objective To investigate whether the interferon-gamma (IFN-gamma) gene (CA)(n) repeat polymorphism is associated with susceptibility to endometriosis. Design Case-control study. Setting University Department of Obstetrics and Gynaecology. Population Women with (n = 622) and without (n = 442) endometriosis. Methods Genotyping was performed by fluorescent polymerase chain reaction (PCR) and gene-scan analysis. Main outcome measures Genotype distribution and allele frequency of the dinucleotide (CA)(n) repeat polymorphism in the IFN-gamma gene. Results Seven alleles (12-18 repeats) of the IFN-gamma gene (CA)(n) repeat polymorphism were found. In both patients with endometriosis and controls the most common allele was composed of 13 repeats, followed by an allele of 15 repeats, and then by an allele of 12 repeats. Patients with endometriosis had a significantly higher incidence of genotypes with alleles composed of fewer repeats (12-13 repeats), compared with the controls (92.0 versus 84.4%, respectively, P < 001). Conclusions Our results suggest that the (CA)(n) repeat polymorphism in the IFN-gamma gene may be associated with a risk of endometriosis in the South Korean population.