Other hints came from methodically trolling through the human genes. And now, scientists hope they've picked up the scent for identifying genes that set up some babies to develop autism.
Nobody can declare a clear victory yet.
A proposed autism gene that captured headlines in November, for example, will have to be confirmed by further research before it's widely accepted. But gene-hunters say the search has been heating up in the past few years, with more funding luring in more investigators, sophisticated tools and techniques being brought to bear, and an encouraging run of tantalizing results. Autism usually appears by age 3, mostly in boys. Affected children have trouble communicating and interacting with others. They may not respond to their names or even look at other people.