Heterogeneity in the genetics of autism

Although it is well accepted that genetics makes a strong contribution to autism spectrum disorder, most of the underlying causes of the condition remain unknown. Three groups present large-scale exome-sequencing studies of individuals with sporadic autism spectrum disorder, including many parent–child trios and unaffected siblings. The overall message from the three papers is that there is extreme locus heterogeneity among autistic individuals, with hundreds of genes involved in the condition, and with no single gene contributing to more than a small fraction of cases. Sanders et al. report the association of the gene SCN2A, previously identified in epilepsy syndromes, with the risk of autism. Neale et al. find strong evidence that CHD8 and KATNAL2 are autism risk factors. O'Roak et al. observe that a large proportion of the mutated proteins have crucial roles in fundamental developmental pathways, including β-catenin and p53 signalling.