I thought this would be an easy find. As she and others looked for the genes, however, they came to think that this inherited influence was split up among more genes than expected, leaving no gene with a powerful and easily traceable influence. That made it harder to find any of them. We now think our estimates of the number of genes is too low, because we haven't done it. Yet he and some others say it's possible that autism will be the next common psychiatric disorder, after Alzheimer's, to yield susceptibility genes.
Scientists can point to encouraging results from a variety of approaches.
One is to scan all the human chromosomes, the rodlike structures that hold genes, for locations that show evidence of harboring an autism gene. That involves analyzing inheritance patterns for particular bits of DNA along the chromosomes. A half-dozen of these scans have been done for autism, and while results have not been uniform, researchers say at least two locations show promise. The big job now, of course, is to search those locations to identify any autism genes they hold. The hunt is already on.