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. 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. In severe cases, they may become aggressive or injure themselves. The hunt for autism genes is complicated. It's not a case of a single flawed gene causing a disease, as in Huntington's or cystic fibrosis . Rather, autism appears to be brought on by unknown environmental influences coupled with a dimly understood combination of genes that makes people vulnerable.