MONDAY, Feb. 18 (HealthDay News) -- A protective effect in females may help explain one of the biggest mysteries of autism: Why boys are five times more likely to develop the developmental brain disorder than girls.
A new, preliminary study suggests that developing females are much better able than males to fight off genetic pressure to develop symptoms of autism.
The findings aren't definitive and don't point to a treatment or cure. Still, "first steps like this are important" and could lead to greater understanding of autism, said study lead author Elise Robinson, an instructor in the department of medicine at Harvard Medical School in Boston.
An estimated 1 in 88 children in the United States has an "autism spectrum disorder." The condition, which can range from mild to severe, is characterized by impaired communication and social interaction. Prevalence of autism is increasing in the United States, although it's not clear if that's largely because there's more awareness of the disorder.
According to the U.S. Centers for Disease Control and Prevention, boys are almost five times more likely than girls to have a form of the disorder -- 1 in 54 boys compared to 1 in 252 girls.
There are many theories about why this autism "gender gap" exists. One idea is that males are threatened in the womb by exposure to testosterone, the male hormone. Another theory holds that females might be somehow inherently better protected against the threat of the condition.
This may fit in with the idea that males are weaker in the womb than females. Boys are generally more prone to develop neurological disorders than girls, noted Dr. Andrew Zimmerman, director of clinical trials at the Lurie Center for Autism at Massachusetts General Hospital.
"We poor males are vulnerable," he said. "Girls have two X chromosomes, so if there's a problem on one, they have a spare." On
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