It is one of many facets of autism they learn to accommodate: their kids' tendency to wander off. Sometimes it's because, like all kids, they are curious. Sometimes it's because their senses are overloaded and they need to get away.

But what's most troubling about the tendency, said Anna Wang, an advocate for children with special needs, is that autistic kids don't always understand danger.

"They don't necessarily run away. They want to explore and just wander off. But they don't know how to identify danger," said Wang, founder of the Friends of Children with Special Needs Dream Center in Fremont. "They don't know it is dangerous to cross the highway."