Pinpointing the specific genes involved in ASDs has been a challenge. The most frequent recurrent CNVs tend to be large (>500 kb) and contain multiple genes. Rare or de novo CNVs have been identified that are smaller (<100 Kb) in size, sometimes disrupting a single gene, but strong statistical evidence is lacking. There are a few genes in which mutations have been consistently detected in multiple studies, and thus these genes are recognized as bona fide risk factors for ASDs. These genes include NGLN4X (Jamain et al., 2003; Laumonnier et al., 2004), SHANK3 (Durand et al., 2007; Gauthier et al., 2009; Moessner et al., 2007), NRXN1(Bucan et al., 2009; Kim et al., 2008; Szatmari et al., 2007), SHANK2 (Berkel et al., 2010; Pinto et al., 2010), CNTN4 (Fernandez et al., 2004, 2008; Glessner et al., 2009; Roohi et al., 2009) and CNTNAP2 (Bakkaloglu et al., 2008; Strauss et al., 2006). Other novel ASD candidate genes include DPYD and DPP6 (Marshall et al., 2008), RFWD2, NLGN1, and ASTN2 (Glessner et al., 2009), SYNGAP1, DLGAP2, and the X-linked DDX53-PTCHD1 locus (Noor et al., 2010; Pinto et al., 2010).
