This new study reported by CNN might show that autism is even more prevalent than we thought:

South Korean study may lead to higher autism estimates
By Miriam Falco, CNN
May 9, 2011 10:29 a.m. EDT

(CNN) — Researchers believe the number of children who have an autism spectrum disorder (ASD) is much higher than previously believed, according to a new study published Monday in the American Journal of Psychiatry.

By looking at a total population sample in South Korea, the study authors estimate that 1 in 38 children in the country — or 2.64% — has some form of autism. The approach is a new one. Previously, researchers have examined only children known to have the neurological disorder or at high risk of developing it.