Maybe one of the reasons is that there is not a definitive diagnosis/screening, hence a significant rate of misdiagnosis.<p><a href="http://en.wikipedia.org/wiki/Autism#Screening" rel="nofollow">http://en.wikipedia.org/wiki/Autism#Screening</a><p>I've even seen claims of 1 in 120 people having some degree of autism which I find ludicrous:<p><a href="http://www.dailypennsylvanian.com/article/penn-study-discovers-increasing-autism-locally-and-nationally" rel="nofollow">http://www.dailypennsylvanian.com/article/penn-study-discove...</a>