Title: Sporadic autism exomes reveal a highly interconnected protein network of de novo mutations.

Authors: Brian J O'Roak, Laura Vives, Santhosh Girirajan, Emre Karakoc, Niklas Krumm, Bradley P Coe, Roie Levy, Arthur Ko, Choli Lee, Joshua D Smith, Emily H Turner, Ian B Stanaway, Benjamin Vernot, Maika Malig, Carl Baker, Beau Reilly, Joshua M Akey, Elhanan Borenstein, Mark J Rieder, Deborah A Nickerson, Raphael Bernier, Jay Shendure, Evan E Eichler

Journal, date & volume: Nature, 2012 May 10 , 485, 246-50

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/22495309

Abstract
It is well established that autism spectrum disorders (ASD) have a strong genetic component; however, for at least 70% of cases, the underlying genetic cause is unknown. Under the hypothesis that de novo mutations underlie a substantial fraction of the risk for developing ASD in families with no previous history of ASD or related phenotypes--so-called sporadic or simplex families--we sequenced all coding regions of the genome (the exome) for parent-child trios exhibiting sporadic ASD, including 189 new trios and 20 that were previously reported. Additionally, we also sequenced the exomes of 50 unaffected siblings corresponding to these new (n = 31) and previously reported trios (n = 19), for a total of 677 individual exomes from 209 families. Here we show that de novo point mutations are overwhelmingly paternal in origin (4:1 bias) and positively correlated with paternal age, consistent with the modest increased risk for children of older fathers to develop ASD. Moreover, 39% (49 of 126) of the most severe or disruptive de novo mutations map to a highly interconnected β-catenin/chromatin remodelling protein network ranked significantly for autism candidate genes. In proband exomes, recurrent protein-altering mutations were observed in two genes: CHD8 and NTNG1. Mutation screening of six candidate genes in 1,703 ASD probands identified additional de novo, protein-altering mutations in GRIN2B, LAMC3 and SCN1A. Combined with copy number variant (CNV) data, these results indicate extreme locus heterogeneity but also provide a target for future discovery, diagnostics and therapeutics.