Autism Spectrum Disorder: gene variants involved in the nonsense-mediated mRNA decay pathway

Genetic factors account for 50-80% of the familial risk of Autism Spectrum Disorder (ASD), but most of the genetic determinants are still unknown and a role for other regulatory mechanisms is likely. The nonsense-mediated decay (NMD) pathway is essential to control mRNA quality and has an important role in the regulation of the transcriptome. Mutations in genes involved in the NMD pathway, such as the UPF3B gene, a core component of this pathway, were previously linked to ASD. In this study we explored the potential role of NMD factors in ASD. We generated a list of 153 genes involved in the NMD pathway using AmiGO, Reactome and a systematic literature review. To identify potentially pathogenic variants in the NMD genes, we analyzed whole exome sequencing data (WES) data from 1338 ASD subjects. We also searched for Copy Number Variants (CNVs) targeting NMD genes in ASD patients (n=3570) and checked their frequency in controls (n=9649). We identified 43 high impact variants in 28 NMD genes, including the UPF3B and ACE, two genes previously implicated in ASD. Importantly, 11 were novel candidate genes that carry loss-of-function and missense (deleterious and damaging) variants with a frequency of 1 to 5% in this ASD dataset. Additionally, 5 NMD genes were found to be targeted by CNVs in 12 ASD subjects but none of the controls. The discovery of 33 NMD genes that are intriguing candidates for ASD in large patient genomic datasets provides evidence supporting the involvement of the NMD pathway in ASD pathophysiology.A.R.Marques is recipient of a fellowship from BioSys PhD programme (Ref PD/BD/113773/2015 from FCT (Portugal).