However, the patients in our survey were part of an epidemiologic study that failed to identify significant in utero exposures accounting for their IL.17 A recent review of de novo mutation rates in autistic spectrum disorders reports that only one de novo mutation per exome is observed in cases that are significantly enriched for de novo mutations.31 Thus, although we cannot distinguish paternal variation from de novo mutations, elevated rates of de novo mutation are insufficient to account for the overall enrichment of variation in candidate genes we have identified in this survey. This evidence concerns the gene IL17A and autism spectrum disorder.