The link between mutations believed to cause autism spectrum disorders and different molecular and behavioral effects, is reported this week in Nature Neuroscience. These findings begin to unravel the relationship between diverse autism mutations and their widely varying clinical presentation.

Dennis Vitkup and colleagues grouped nearly 1000 genes, which have previously been found to be mutated in patients with autism spectrum disorders, based on their genetic effects. Mutations found in patients with autism spectrum disorders, compared to the benign mutations in their healthy siblings, affect genes that are more highly expressed in the brain. The authors found that this was more pronounced in female patients where the genes were expressed at levels up to twice as high as those in males.

In addition, mutations that abolish the function of a gene completely were found in patients with low IQ scores, whereas those with less severe mutations had normal intellectual function. Given that both classes of mutations affect the same molecular and cellular processes the results indicate that mutations with stronger functional effects are associated with worse autism features.