Sexual identity is wired into the genes, which discounts the concept that homosexuality and transgender sexuality are a choice, University of California researchers reported.
"Sexual identity is rooted in every person's biology before birth and springs from a variation in our individual genome," a UCLA genetics professor, said in a statement. His team has identified 54 genes in mice that may explain why male and female brains look and function differently.
Since the 1970s, scientists have believed that estrogen and testosterone were wholly responsible for sexually organizing the brain. Recent evidence, however, indicates that hormones cannot explain everything about the sexual differences between male and female brains.
Published in the latest edition of the journal Molecular Brain Research, the UCLA discovery may also offer physicians an improved tool for gender assignment of babies born with ambiguous genitalia. Mild cases of malformed genitalia occur in 1 percent of all births -- about 3 million cases. More severe cases -- where doctors can't inform parents whether they had a boy or girl -- occur in one in 3,000 births.
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Adult hyperactivity drug approved: British drugmaker Shire Pharmaceuticals Group said that U.S. authorities had signaled their readiness to approve an adult version of the firm's top-selling hyperactivity drug.
Britain's third-biggest drugmaker, which already draws over a third of revenues from Adderall XR for use in children, said the adult market was twice the size of the pediatric market. It said it had received an "approvable" letter from the FDA for adult Adderall, used to treat attention deficit hyperactivity disorder.
The FDA issues such a letter when it is ready to approve a drug but still requires a firm to meet certain conditions, such as labeling. Shire's research and development director said the approvable letter enabled the firm to develop its position as market leader in the treatment of hyperactivity.
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Hope for migraine sufferers: Pozen said one of its experimental migraine drugs provided both reduced pain and relieved other symptoms of migraine, such as nausea and sensitivity to sound and light, in late-stage clinical trials.
The issue of relieving both "primary" and "secondary" targets is important because earlier in the day Pozen reported that the FDA rejected a different migraine drug because it did not significantly reduce the secondary goals, despite relieving pain. But the drug MT 100, a combination of a painkiller and an anti-nausea drug, significantly reduced nausea and sensitivity to sound and light, said Pozen's CEO.
The FDA declined to approve one of the company's other migraine drugs, MT 300, because it did not significantly reduce nausea and sensitivity to sound and light.
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Americans want health care: The public's growing unease with the current health-care system has built support for a new approach that would mean care for all Americans and changes in laws governing prescription drugs, a poll suggests.
A sizable majority, 70 percent, said it should be legal for Americans to buy prescription drugs outside the United States, according to the ABC News-Washington Post poll. One in eight respondents said they or someone in their home has done that. Such purchases can save money but they violate the law.
The poll released Sunday found that more than half of Americans, 54 percent, are dissatisfied with the overall quality of health care in the United States, while 44 percent are satisfied. That dissatisfaction is 10 percentage points higher than in 2000 and higher than it has been in the past decade when compared with earlier surveys.
While a solid majority of people tended to be happy with their own quality of health care, the poll found "significant concern with the system more broadly," said ABC pollster Gary Langer, who directed the extensive survey. Those concerns included worries about future costs, declining coverage and the problems of people who lack insurance.
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Compiled by Kari L. Dean. Reuters and AP contributed to this report.
