Gene defect found for unexplained male infertility
Baku, July 25 (AZERTAC). Researchers may have found a clue to male infertility that could help explain why so many cases can`t be explained. University of California -Davis scientists discovered a defect in the DEFB126 gene that they say is carried by a high number of men. When the gene is mutated, sperm can`t get through cervical mucus because it lacks a protein coat needed to evade the immune system.
The researchers note the importance of the finding. In their DNA sampling from the U.S., United Kingdom, China, Japan and Africa they found that half of men have at least one DEFB126 gene mutation. Twenty five percent of men were found to have two defective copies of the gene that they say significantly affects male fertility.
The gene acts like a cloaking device, providing sperm with a necessary protein that has nothing to do with sperm quality and quantity. Even when sperm looks good under the microscope, it can`t get to the egg without the protein coat.
Gary Cherr, a professor at the UC Davis Bodega Marine Laboratory and Center for Health and Environment and senior author of the paper explains, "In 70 percent of men, you can`t explain their infertility on the basis of sperm count and quality.”
Ted Tollner, first author of the paper says it`s been a mystery as to why sperm quality and quantity has so little to do with male fertility.
The discovery came about when Tollner and Cherr were investigating how to make contraceptive vaccines.
The researchers explain DEFB126 is made in the epididymis where sperm is stored. The gene provides a thick coating. The scientists were trying to make an antibody against the protein that belongs to a class of defensins, with little success.
Male fertility seems to be on the decline worldwide. The researchers say the DEFB126 gene mutation, found in a significant number of men, might explain high rates of male infertility. They also say there may be a reason the gene mutation is so prevalent. The next step is to understand why the sperm mutation is so prevalent.
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