Researchers Discover Sex-Change Gene

Researchers at the University of Minnesota Medical School and College of Biological Sciences have discovered a gene that is required to maintain male sex throughout life.

The research team, led by David Zarkower and Vivian Bardwell of the University of Minnesota’s department of genetics, cell biology, and development, found that removing an important male development gene, called Dmrt1, causes male cells in mouse testes to become female cells. The findings were published today in the online edition of Nature.

According to Medical Xpress, a Web-based medical and health news service, the study determined that in mammals, sex chromosomes (XX in female, XY in male) determine the future sex of the animal during embryonic development by establishing whether the gonads will become testes or ovaries.

"Scientists have long assumed that once the sex determination decision is made in the embryo, it's final," Zarkower said. "We have now discovered that when Dmrt1 is lost in mouse testes — even in adults — many male cells become female cells and the testes show signs of becoming more like ovaries."

Previous research has shown that removing a gene, called Foxl2, in ovaries caused female cells to become male cells and the ovaries to become more like testes. According to Zarkower, this latest research determines that the gonads of both sexes must actively maintain the original sex determination decision throughout the remainder of life.

This discovery is a breakthrough for genetic researchers and may have implications for transgender and intersex individuals.

"This work shows that sex determination in mammals can be surprisingly prone to change and must be actively maintained throughout an organism's lifetime," said Susan Haynes, who oversees developmental biology grants at the National Institute of General Medical Sciences of the National Institutes of Health. "These new insights have important implications for our understanding of how to reprogram cells to take on different identities and may shed light on the origin of some human sex reversal disorders."