>> this naib --neighborhood may be typical now, two families with autistic children, aiden, who lives here, is one of about 30,000 bay area children diagnosed with autism. two hours ago, nine-year-old aiden stepped off the bus. he goes to a special school. his mom says he was diagnosed at two years old. >> he was 26 months. didn't talk. through -- threw tantrums all day long. screamed, cried. he was miserable. i couldn't reach him. >> reporter: 1 in 88 children now have diagnoseable autism. that's a startling increase in a decade. >> there's a sense of urgency now. >> how much of the increase is a result of better tracking and how much of it is the result of an actual increase? we still don't know. >> scientists discovered several genes associated with autism. experts point to external triggers. >> we're talking about infections, social conditions, and we're talking about exposures to toxicants, things in the environment. >> intensive treatment, if begun early, can significantly help children. the problem is, autism-related costs have tripled in a decade. now $126 billion a year, acco