Almost half of US children diagnosed with Autism Spectrum Disorder wander away from safe places, and about half go missing long enough to alarm their parents, a new study out Monday found.

The study published in the journal Pediatrics on research by the Kennedy Krieger Institute that looked at more than 1,200 families highlighted how significant a concern the issue is, the authors wrote.

"We have (long) heard from families of children with autism that their children often place themselves in danger by wandering or eloping," said lead author Dr Paul Law, senior author and director of the IAN Project at the Kennedy Krieger Institute.

"These are the first published findings in the United States that provide an estimate of the number of children with ASD who not only wander or elope, but go missing long enough to cause real concern."

The study found that 49 percent of children with ASD attempted to run away at least once after age 4. And of those who attempted to wander or bolt, 53 percent went missing long enough to cause concern.

"Children who were reported as missing were older, more likely to have experienced skill loss and less likely to respond to their name. They were also more likely to have lower intellectual and communication scores than non-missing children," Law wrote.

Autism, Asperger Syndrome and other related disorders are diagnosed in one out of 88 children in the United States, according to the Centers for Disease Control.