Scientists close in on sex gene mystery

Updated December 23, 2010 15:08:00

Scientists say they are one step closer to solving one of the mysteries of human sexual development.

Scientists at the University of Adelaide have found an ancient brain gene responsible for tricking foetuses into forming male sex organs without a Y chromosome.

They have created a male mouse without a Y chromosome by activating the gene in the foetus.

Males usually have an X and Y chromosome, while females have two X chromosomes.

The gene was known to have been important for brain development, but scientists were not aware of its ability to trigger the development of testicles.

Associate Professor Paul Thomas from the university's school of molecular and biomedical science says it is an important breakthrough.

"What we've done is generate mice that have extra copies of this brain gene and shown that they develop as males instead of females," he said.

"This came as quite a surprise to us, as you might imagine.

"We found we had many more males than predicted and that's because the gene is causing them to develop as males."

Associate Professor Thomas says the gene is responsible for about 20 per cent of the cases for the rare X-X male sex change syndrome, seen in one in every 20,000 men.

"It is all happening during embryonic development, so it's very difficult to reverse that," he said.

"I think the main impact for the foreseeable future is that we'll be able to help with the diagnosis of this condition at a genetic level," he said.

Topics: research, university-and-further-education, science-and-technology, animal-science, breakthroughs, dna, genetics, adelaide-5000, sa

First posted December 23, 2010 12:12:00