Progesterone receptor polymorphism +331G/A is associated with a decreased risk of deep infiltrating endometriosis

Alterations in the progesterone receptor (PR) are considered a risk factor for the development of endometriosis. In this study, the frequencies of the PROGINS and +331G/A polymorphisms of the PR gene were determined in deep infiltrating endometriosis and correlated with the expression of the PR protein.

The frequencies of the PR polymorphisms were determined in women with deep infiltrating endometriosis (n = 72), women with adenomyosis in the uterine wall (n = 40), gynaecological patients without symptomatic endometriosis (n = 102) and healthy females (n = 93). Detection of +331G/A and PROGINS polymorphisms was performed using PCR-restriction fragment length polymorphism (RFLP) analysis. Expression of PR-A and PR-B protein was assessed with immunohistochemistry. The allelic frequency of the polymorphic allele +331A was lower in women with endometriosis (P < 0.01) and adenomyosis (P < 0.02) compared with healthy females. The frequency of the PROGINS polymorphism did not differ between the groups. The mean staining index (SI) for PR-B in endometriotic epithelium was higher in the presence of the +331A polymorphic allele (n = 2) (P < 0.001) compared with +331G/G individuals (n = 61). The PROGINS polymorphism did not affect the SI for PR-A and PR-B.

The presence of the PR gene polymorphic allele +331A is associated with a reduced risk of deep infiltrating endometriosis and adenomyosis compared with healthy population controls. The PROGINS polymorphism does not seem to modify the risk of deep infiltrating endometriosis.