Vitamin D-related genes are subjected to significant de novo mutation burdens in autism spectrum disorder

Exome sequencing of 343 families, each with a single child on the autism spectrum and at least one unaffected sibling, reveal de novo small indels and point substitutions, which come mostly from the paternal line in an age-dependent manner. We do not see significantly greater numbers of de novo missense mutations in affected versus unaffected children, but gene-disrupting mutations (nonsense, splice site, and frame shifts) are twice as frequent, 59 to 28. Based on this differential and the number of recurrent and total targets of gene disruption found in our and similar studies, we estimate between 350 and 400 autism susceptibility genes. Many of the disrupted genes in these studies are associated with the fragile X protein, FMRP, reinforcing links between autism and synaptic plasticity. We find FMRP-associated genes are under greater purifying selection than the remainder of genes and suggest they are especially dosage-sensitive targets of cognitive disorders. Copyright © 2012 Elsevier Inc. All rights reserved.

Evidence for the etiology of autism spectrum disorders (ASD) has consistently pointed to a strong genetic component complicated by substantial locus heterogeneity 1,2 . We sequenced the exomes of 20 sporadic cases of ASD and their parents, reasoning that these families would be enriched for de novo mutations of major effect. We identified 21 de novo mutations, of which 11 were protein-altering. Protein-altering mutations were significantly enriched for changes at highly conserved residues. We identified potentially causative de novo events in 4/20 probands, particularly among more severely affected individuals, in FOXP1, GRIN2B, SCN1A, and LAMC3. In the FOXP1 mutation carrier, we also observed a rare inherited CNTNAP2 mutation and provide functional support for a multihit model for disease risk 3 . Our results demonstrate that trio-based exome sequencing is a powerful approach for identifying novel candidate genes for ASD and suggest that de novo mutations may contribute substantially to the genetic risk for ASD.

New technologies enabling genome-wide interrogation have led to a large and rapidly growing number of autism spectrum disorder (ASD) candidate genes. Although encouraging, the volume and complexity of these data make it challenging for scientists, particularly non-geneticists, to comprehensively evaluate available evidence for individual genes. Described here is the Gene Scoring module within SFARI Gene 2.0 (https://gene.sfari.org/autdb/GS_Home.do), a platform developed to enable systematic community driven assessment of genetic evidence for individual genes with regard to ASD.