健康英语新闻:Sperm coat protein may be key to male infertility: study

WASHINGTON, July 20 (Xinhua) -- The loss of a protein that coats sperm may explain a significant proportion of infertility in men worldwide, according to a study by an international team of researchers led by University of California Davis.

A paper describing the work was published Wednesday in the journal Science Translational Medicine. The research could open up new ways to screen and treat couples for infertility.

The gene DEFB126 encodes a protein called Beta Defensin 126, which coats the surface of sperm and helps it penetrate cervical mucus in the female. A survey of samples from the U.S., Britain and China showed that as many as a quarter of men worldwide carry two copies of the defective gene.

In the new study, researchers found that men with a muted DEFB126 lack Beta Defensin 126, making it much more difficult for sperm to swim through the mucus and eventually join with an egg.

Examining 500 newly married Chinese couples, researchers found that the lack of Beta Defensin 126 in men with the DEFB126 mutation lowered fertility (even among men that did not display other deficiencies usually associated with infertility, like inadequate semen volume and low sperm motility). Wives of men with the Beta Defensin 126 variant were significantly less likely to become pregnant than were other couples, and 30 percent less likely to have a birth.

This genetic variation in DEFB126 likely accounts for many unexplained cases of infertility, researchers say. They hope next to work with a major infertility program in the U.S. to further explore the role of the mutation.