everyone knows when we do that, when we have the genetic land scain, when we understand what the genetic risk factors are, then we have to find out where in the brain these genes are working, when in the brain they're operative. is it prenatal during the first, second or third trimester of birth or is it in certain critical periods later in development? there's evidence that some autism follows a pattern of regression, children that develop normally for a period of time. although this is a strong debate in the literature but it may be there are different critical periods. autism is not going to be a simple one gene one disease phenomenon. in fact the best estimates i know of suggest there may be more than 100 genes that enhance the risk of autism. and they may act at different times in different ways. that's what challenge is. >> charlie: the most important thing is identifying these genes or are there other things that we're making dramatic progress in autism because it is something i've heard more and more about over the last four or five years. is that because there are more cases or