Male Infertility Cure May Lie in Sperm Proteins

Little is understood about male infertility, but if faulty sperm proteins can be found, the discoveries may lead to new approaches to infertility testing and treatment, according to a paper by two San Francisco State University researchers. Co-authors Diana Chu and Tammy Wu claim that roughly 50 percent of male infertility cases have no clearly identifiable cause and therefore no direct treatment.

Chu adds that study of infertility on the molecular level has tremendous potential to inform development of effective diagnostic tools and successful treatments. The researchers suggest that the study of sperm proteins has great use in the clinic and can help people move from infertile to fertile and ultimately help couples conceive.

For their paper, Chu and Wu carefully examined a selection of recent studies that have discovered a correlation between male infertility and a selection of more than 2,000 proteins present in each man’s sperm, a number of which are unique in all of the body. Amongst each individual man, there are slight variations in the sperm protein content. Scientists suspect that these variations can contribute to male infertility.

If these suspicions are true, techniques can be engineered to test for these specific protein abnormalities, and certain pharmaceuticals can be developed to address these issues. Chu concludes that the ultimate goal is for a doctor to be able to say to their patient, ‘There is a misregulated protein in yours sperm, but there is a drug that corrects it or decreases the level of that protein.’ Understanding these complex proteins also allows the doctor to inform patients about the likely success rates of varying fertility therapies, an important factor, considering the high cost of fertility treatments.

Research published in the journal Science Translational Medicine indicates that a team of researchers led by UC Davis have identified the loss of a sperm-coating protein that could account for a large proportion of infertility among males. This research has the potential to open up new avenues of screening and treatment for male infertility.

According to senior author of the paper, Gary Cherr, the protein DEFB126 works as a “cloaking device” that allows sperm to successfully swim through mucus and avoid the immune system in order to reach the egg. However, researchers have discovered that a number of men carry a defective gene for DEFB126. A survey of samples collected from the U.S., U.K. and China indicates that as many as a quarter of men worldwide carry two copies of the defective gene, which may greatly affect their fertility.

If the discovery is successfully engineered into a test, it could be used to send couples directly to treatment with intracytoplasmic sperm injection (ICSI), in which eggs are removed from the women and injected directly with sperm, avoiding additional expensive testing to exclude other possible causes. Cherr believes that the next major step is collaboration with a major infertility program in the U.S. to further explore the role of the mutation in male infertility.


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