Genetic Find Could Open Door for New Male Contraceptives

Study reveals gene behind sperm development, offering hope for families as well as new contraceptives.

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Sedentary behavior has been linked to higher scrotal temperatures before.

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Scientists have found a gene that plays an integral part in male fertility, giving researchers hope for the future development of hormone-free male birth control and perhaps solving some men's infertility woes within the next five years.

In mice, a mutation to the Katnal1 gene prevents the production of viable sperm, which makes it impossible for them to fertilize an egg.

['The Pill' for Him]

"It stops the production of functional sperm, so they're released before they mature," says Lee Smith, a University of Edinburgh researcher and lead author of the study. Smith's team believes the gene likely has the same function in humans. "There's very good male contraceptives out there based on testosterone treatments and non-hormonal concepts based on preventing passage of sperm from the vas deferens, but what we're trying to do here is provide different birth control options."

His team says a re-engineered virus carrying a mutated form of the gene could be injected into the testes to render a man permanently sterile, essentially creating a "genetic vasectomy," with a long-term goal of creating a reversible procedure.

[Should Men Care That Birth Control Options are Languishing?]

Effective, non-hormonal male birth control has remained elusive for researchers, but in recent months, doctors have made progress. In India, several people have gotten what's known as a RISUG treatment—a 15-minute procedure in which a gel is injected into the vas deferens, making it impossible for sperm to exit the penis. The procedure is reversible and effective for about 10 years.

For infertile men, Smith says his team is working on a method to "reverse infertility" in mice who have a mutated Katnal1 gene using a similar viral process—a working version of the gene would be injected into the testes.

Before the Edinburgh College study, scientists didn't know the gene played any role in sperm development. Smith says the discovery could be "one piece of the puzzle" to determining male infertility problems. As personalized genome sequencing becomes cheaper and more common, doctors could quickly scan to see if a patient had a mutated Katnal1 gene.

"Taking it to humans would be a long process," he says. "But it could be a factor in some male infertility cases. It's one of the genes that clinicians will sequence to determine which gene is causing a problem in each individual guy."

Jason Koebler is a science and technology reporter for U.S. News & World Report. You can follow him on Twitter or reach him at jkoebler@usnews.com