Gene Tied to Female Infertility Found

Mouse equivalent produces early ovarian failure

THURSDAY, May 2, 2002 (HealthDayNews) -- Federal scientists have discovered a gene that may make some women infertile.

While the research is in its preliminary stages, the findings may lead to treatments for women with two separate problems -- premature menopause and an inability to produce viable eggs, says Dr. Lawrence Nelson, a clinical investigator with the National Institute of Child Health and Human Development.

"We're starting down a path," he says, "but who knows if we'll get there?"

The discovery is of the human equivalent of a gene that scientists dubbed Mater. They know what it does in mice, but not whether it behaves the same way in humans.

Nelson and his colleagues found the gene while studying premature ovarian failure, a little-understood disorder that causes women under 35 to undergo symptoms of menopause, including hot flashes and the cessation of periods.

"We only understand the cause in about 10 percent of the women," Nelson says. "In most cases, it remains a mystery."

The cure is also elusive. Doctors can replace missing female hormones with drug treatment, but that won't restore the women's fertility, Nelson says.

In some cases of premature ovarian failure, a woman's immune system attacks her ovaries. The researchers were trying to determine exactly what the immune system was attacking in the ovaries. They found a protein that looked like a target and bred mice without the Mater gene, which creates the protein.

They report their findings in the April issue of the journal Human Reproduction.

"The male and female mice looked completely normal in every way we could test," Nelson says, but the female mice turned out to be infertile.

While their bodies created eggs and sperm from male mice fertilized them, the embryos died after dividing into two cells. That suggests the gene creates a protein the embryos need in order to live, Nelson says.

"We expect it will have the same function in humans as in mice, but we haven't proven that yet," he says.

If the gene does function in a similar fashion in humans, it could explain the mystery of infertility in some women.

"There are women who show up in a fertility clinic, go through a complete evaluation and everything looks normal, but they just can't explain their lack of fertility," Nelson says.

Doctors may find some women are infertile because they are missing the gene and don't create a protein necessary for embryo development, Nelson says. In that case, doctors could inject the woman's eggs with the missing protein and then reinsert them into the womb.

Those hopes may be optimistic, cautions Alan Schneyer, an associate professor of medicine at Harvard Medical School. While the researchers offer "interesting conjecture," they haven't confirmed their findings in mice have anything to do with humans, he says.

What To Do: For more information on infertility, visit the InterNational Council on Infertility Information Dissemination. Learn more about premature ovarian failure from the POF Support Group.

SOURCES: Lawrence Nelson, M.D., clinical investigator, National Institute of Child Health and Human Development, Bethesda, Md.; Alan Schneyer, Ph.D., associate professor, medicine, Harvard Medical School, Boston; April 2002 Human Reproduction
Consumer News