Complete Disruption of Autism-Susceptibility Genes by Gene Editing Predominantly Reduces Functional Connectivity of Isogenic Human Neurons

Abstract

Summary: Autism spectrum disorder (ASD) is phenotypically and genetically heterogeneous. We present a CRISPR gene editing strategy to insert a protein tag and premature termination sites creating an induced pluripotent stem cell (iPSC) knockout resource for functional studies of ten ASD-relevant genes (AFF2/FMR2, ANOS1, ASTN2, ATRX, CACNA1C, CHD8, DLGAP2, KCNQ2, SCN2A, TENM1). Neurogenin 2 (NGN2)-directed induction of iPSCs allowed production of excitatory neurons, and mutant proteins were not detectable. RNA sequencing revealed convergence of several neuronal networks. Using both patch-clamp and multi-electrode array approaches, the electrophysiological deficits measured were distinct for different mutations. However, they culminated in a consistent reduction in synaptic activity, including reduced spontaneous excitatory postsynaptic current frequencies in AFF2/FMR2-, ASTN2-, ATRX-, KCNQ2-, and SCN2A-null neurons. Despite ASD susceptibility genes belonging to different gene ontologies, isogenic stem cell resources can reveal common functional phenotypes, such as reduced functional connectivity. : In this article, Scherer and colleagues present a human induced pluripotent stem cell (iPSC) knockout resource for functional studies of ten genes associated with autism spectrum disorder. They also show that some of these genes, pertaining to diverse functional categories, can underlie common phenotypes in CRISPR-isogenic iPSC-derived glutamatergic neurons. Keywords: iPSC, CRISPR, isogenic, knockout, StopTag, NGN2, autism, convergence, sEPSC