Matrix metalloproteinase and tissue inhibitors of metalloproteinases gene polymorphisms in disorders that influence fertility and pregnancy complications: A systematic review and meta-analysis

Matrix metalloproteinase (MMP) and tissue inhibitors of metalloproteinase (TIMP) gene polymorphisms have been extensively evaluated as predisposing factors to human reproductive disorders. However, the evidence available is inconsistent. Therefore, we performed a systematic review and meta-analysis to provide the first comprehensive synopsis of case-control studies that investigated the association of MMP and TIMP gene polymorphisms with disorders that influence fertility and pregnancy complications. Literature search was performed using PubMed and Scopus databases. We included 42 case-control studies in the systematic review for the following disorders: adenomyosis, endometriosis, hypertensive disorders of pregnancy, preterm birth and recurrent spontaneous abortion. Although a large number of MMP and TIMP gene polymorphisms were tested, no exclusive and unambiguous risk factors were identified for any of the disorders. The majority of statistically significant associations were confirmed in just one study. Additionally, we performed two meta-analyses for MMP9 rs3918242 polymorphism in endometriosis/adenomyosis and preeclampsia but found no association with either disorder. Considering the modest associations and conflicting results between individual case-control studies, new data is needed for further research of this subject.