Mutation of a gene for a protein that coats sperm may be the cause of most cases of male infertility, according to a study published in the journal Science Translational Medicine.
The report, which has involved an international team of researchers and has been led by Professor Gary Cherr, University of California Davis, could open new ways to solve problems of infertility of couples.
The scientists took DNA samples in the U.S., UK, China, Japan and Africa, and found that a quarter of the world’s men carry a defective gene that affects DEFB126 protein, which is responsible for coating the surface of sperm and helps penetrate the cervical mucus of women.
In men with this variant of the protein DEFB126, lack the Beta Defensin 126, which makes it much more difficult for the sperm to swim through mucus and eventually join an egg, according to researchers who suggest that this genetic variation ” is possibly responsible for several cases of unexplained infertility. ”
In examining 500 newly married Chinese couples, scientists discovered that the lack of Beta Defensin 126 in males with the mutation DEFB126 decreased fertility by 30%.
Ted Tollner associate professor of urology at UC Davis and co-author of the study said in a statement that one of the mysteries of human fertility is that the quality and quantity of sperm has little to do with male fertility.
So this new discovery could open new avenues for further study of the role of this mutation in infertility.
Tollner said that compared with sperm from monkeys and other mammals, human sperm are generally of poor quality, slow swim and have a high rate of defective cells.
Professor Cherr said may be due to the fact that humans, unlike most mammals, the perpetuation of the race is based on a monogamous relationship and “sperm quality just does not matter much.”
Experts say some researchers believe that, for reasons unknown, human male fertility has been declining worldwide in recent decades and believe that behind these figures could be problems related to the mutation of the protein DEFB126.