Analysis of the Relationship between CGB5 155G/C Polymorphism and in vitro Fertilization-embryo Transfer Outcome (IVF-ET) in the Iranian Population

Successful pregnancy depends on the ability of the embryo to achieve appropriate extent of trophoblastic proliferation and invasion into maternal endometrium as well as, once implanted, to induce its own blood supply. Beta Human chorionic gonadotropin (β-hCG), enhances blastocyst implantation, uterine vascularization, and angiogenesis, as well as regulates maintenance of uterine quiescence and immunological adaptation during pregnancy. The β-subunit of hCG is encoded by CGB3, CGB6, CGB5, CGB7 and CGB8 genes. The aim of this study was to evaluate the association of CGB5-G/C polymorphism and the clinical outcomes in women who underwent IVF-ET procedures.
A total of 200 patients undergoing IVF-ET (100 patients with positive and 100 patients with negative IVF-ET outcome) were included in this study. Genotyping of CGB5 at -155G/C polymorphic site was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Statistical analysis was performed using the MedCalc software.
Our findings show that the CC genotype of the CGB5 -155G/C polymorphism is associated with decreased risk of IVF-ET failure (OR=0.29; 95%CI=0.1-0.85; p=0.02). However, the allelic distribution of the CGB5 -155G/C is not significantly different between two groups (χ2=1.46; p=0.22).
The results of this study suggested that CGB5 (-155G/C) CC genotype has a protective effect on IVF-ET outcome. More studies with larger sample sizes on different populations are necessary to elucidate the underlying mechanisms which can explain the associations found between the GGB5 gene polymorphisms and IVF-ET outcome.