Genetic and Protein Analysis of Betadefensin 126 and Association with Success Rate of Intrauterin Insemination

Abstract

Introduction: Human β-defensin 126 (DEFB126) is a small cationic glycoprotein that is considered as an important component of the primates and human sperm glycocalix. It protects sperm from infection-causing microbes and against the female immune system antibodies. Human DEFB126 gene is located on the sub-telomeric region of 20p13. DEFB126 variations caused by a frame shift deletion of two cytosines was found to affect the sperms functionality. The aim of this study was to verify the correlation of this gene mutation with success rate of IUI.

Methods: In the present study, the rate of DEFB126 gene mutation was elucidated in 76 Iranian men with unexplained infertility whose wives had undergone IUI with either positive or negative results. DNA properties quantified with NanoDrop spectrophotometers. Standard PCR, Single-strand conformation polymorphism (SSCP) and sequencing were used to confirm the results. Moreover,immunocytochemistry was performed for the assessment of the protein expression on sperm cells.

Results: DNA quantification revealed that 24.4% of men, whose wives showed a negative result for IUI, were homozygote for this mutation, whereas none of the couples with a positive IUI result carried the mutation for this gene (P≤0.05). Moreover, the amount of this protein was decreased on the sperms of men who carried the mutant allele.

Conclusion: Results of the present study suggested that common alteration in DEFB126 gene could be considered as a critical factor in the success rate of IUI operation.