Researchers from UC Davis have found a connection between the outer protein coating of sperm and male fertility. According to researchers, when the outer protein coating is lost, fertility is lost. The protein coating acts as a protective barrier between sperm and the female immune system. The sperm remains “hidden” as it swims toward the egg. When the sperm’s protein coating is lost, the immune system recognizes the sperm as an outside force and attacks it. The result is reduced fertility or infertility. 

It is estimated that as many as 25-percent of the men carry a defective gene that inhibits the production of DEFB126, also known as the protein coating on sperm. Despite current practices of evaluating sperm quantity and quality, there are still many unanswered questions regarding male infertility. About 70-percent of men who suffer from male infertility have no idea why they cannot produce children. At least some of these cases may be attributed to the defective DEFB126 gene. 

DEFB126 first came to the attention of researchers when doctors were trying to create a male birth control. According to Professor Charles Bevins from the UC Davis Department of Medical Microbiology and Immunology, “If we hadn't seen this in the first clone, we would be confused to this day.” If a treatment were developed to stop the production of DEFB126, sperm could not survive in the female body and thus, the treatment would have a birth control effect. Now, it seems, this protein could be the cause of natural male infertility, in some cases. 

The study revealed that about 50-percent of men have one copy of the defective gene and 25-percent of men carry two copies of the defective gene. Men with two copies are more likely to suffer from male infertility. Some experts believe low sperm quality and defective DEFB126 genes may be associated with monogamy. Conceiving children in a monogamous relationship simply means there is more time to procreate. Many animal species breed at select times during the year and switch partners every breeding season. In animal species, sperm quality is much higher and there are much fewer cases of infertility. 


Source: Science Transitional Medicine. T. L. Tollner, S. A. Venners, E. J. Hollox, A. I. Yudin, X. Liu, G. Tang, H. Xing, R. J. Kays, T. Lau, J. W. Overstreet, X. Xu, C. L. Bevins, G. N. Cherr. 21 July, 2011.