A new study says children who have older siblings with autism have a higher risk of developing the disorder than previously thought.

Researchers at the University of California at Davis studied more than 650 infants who have an older sibling with autism, and found 19 percent of the younger children were also diagnosed with the disorder.

Previous studies showed the rate between 3 percent and 14 percent.

The risk of developing autism was higher for male infants in the study, and highest for those with more than one older sibling with autism. The disorder is known to be more common in boys.

There has been no established cause shown for autism, which affects a child's social skills and limits the ability to interact with the outside world.

The study was published online Monday and will appear in the journal Pediatrics.