Nonrandom occurrence of multiple de novo coding variants in a proband indicates the existence of an oligogenic model in autism.

ABSTRACT

PURPOSE: Elucidating the genetic architecture underlying autism spectrum disorder (ASD) will aid in the understanding of its genetic etiology and clinical diagnosis. METHODS: A comprehensive set of coding de novo variants (DNVs) from 4504 trios with ASD and 3012 control/sibling trios from several large-scale sequencing studies were collected and combined. Multiple in-depth analyses including DNVs burden, clinical phenotypes, and functional networks underlying the combined data set were used to evaluate the nonrandom occurrence of multiple extreme DNVs (loss-of-function and damaging missense variants) in the same patients. RESULTS: We observed a significant excess of multiple extreme DNVs among patients with ASD compared with controls. Meanwhile, patients with ASD carrying 2+ extreme DNVs had significantly lower IQs than patients carrying 0 or 1 DNV. Moreover, much closer functional connectivity than expected was observed among 2 or more genes with extreme DNVs from the same individuals. In particular, we identified 56 key genes as more confident ASD genes compared with other known ASD genes. In addition, we detected 23 new ASD candidate genes with recurrent DNVs, including VIP, ZWILCH, MSL2, LRRC4, and CAPRIN1. CONCLUSIONS: Our findings present compelling statistical evidence supporting an oligogenic model and provide new insights into the genetic architecture of ASD.