K.J.A.F. van Kaam 1 *, A. Romano 1, J.P. Schouten 1, G.A.J. Dunselman 1, and P.G. Groothuis 1
1 Research Institute GROW, University of Maastricht; Department of Obstetrics and Gynaecology, University Hospital Maastricht, Maastricht, The Netherlands
* To whom correspondence should be addressed.K.J.A.F. van Kaam, E-mail: firstname.lastname@example.org
BACKGROUND: 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. METHODS AND RESULTS: 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. CONCLUSIONS: The presence of the PR gene polymorphic allele +331A is associated with a reduced risk of deep infiltrating endometriosis and adeno-myosis compared with healthy population controls. The PROGINS polymorphism does not seem to modify the risk of deep infiltrating endometriosis.Keywords: +331G/A/endometriosis/progesterone receptor/PROGINS.