Mutated gene reduced male fertility: study

Mutated gene reduced male fertility: study - A genetic mutation that reduces a coating of carbohydrates to remove sperm and their motility may explain why some men are less fertile than others, said investigators on Thursday.

The study, published in the journal Science, Translational Medicine, found that couples who had the most problems, the concept, where the men inherited both copies of the mutated gene, one from their father and one was from the mother.

The loss of this coating makes it more difficult for sperm to travel through fluids in the female genital tract, which in turn reduces the rate of conception, said lead author Theodore Tollner.

With sperm donated by 19 participants, observed Tollner and colleagues found that sperm from donors who both copies of the mutated gene, DEFB126 had the most limp issued.

"We have found that sperm from donors lacking the normal gene have difficulty penetrating the mucus surrogate or swimming (in the laboratory dish)," said Tollner, assistant adjunct professor at the Center for Environmental Health at the University of California.

"The speed with which they are able to penetrate the mucus-like gel is 15 to 20 percent of that observed for sperm from donors with the normal gene," Tollner said in an e-mail response to questions from Reuters.

The World Health Organization defines infertility become pregnant and the problem occurs about 13 to 14 percent of couples in many countries around the world as the inability of a couple, after a year of unprotected sex.

In about half of infertile couples the cause was with the men and experts traditionally low sperm count have been responsible. The paper by Tollner and colleagues is the first time that experts in order to show the loss of a coating to sperm.

Steven Rozen of the Duke University-NUS Graduate Medical School in Singapore, which was not related to the study, said this genetic mutation is "quite common".

"This means that a large proportion of men were affected. Depending on the population, 20 to 30 percent of men have two copies of the variant low birth rates, which means their sperm defect in the coating," Rozen said Reuters.

COUPLES TRACKED

To test their hypothesis, the researchers recruited 509 young couples in China and pursued it for almost two years. The average age of men was 25.8 and women 23.4.

Men without gene mutation, men with a copy of the mutated gene and men with two copies of the mutation: The couples were placed into three groups according to the DNA of humans.

By the end of the study, women had 71 percent of the men designed with two copies of the mutated gene, compared to 81 percent of the wives of men with one or none of the mutated gene.

"Our key finding was that the rate of births among couples where the man had two copies of the mutation was DEFB126 30 percent lower than in other couples," Scott Venner, assistant professor, wrote of Epidemiology at Simon Fraser University Faculty of Health Sciences.

"This most likely indicates that the DEFB126 mutation reduces the rate of conception in these couples and it took longer to achieve pregnancy," he told Reuters.

When helping couples conceive, the doctors should more direct interventions such as in vitro fertilization or intrauterine insemination, when they see that the male partner has this gene mutation found, said Toellner.