Unraveling the Genetic Programs Engaged in ASD Neurons Through Coupled Transcriptomic and Phenotypic Readouts

Broad Institute, Inc., Cambridge MA

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Abstract

Autism spectrum disorders (ASD) are genetically diverse, characterized by both rare variants of large effect size and common variants of small effect size. Identifying the molecular mechanisms resulting from these variants presents a key challenge for the development of clinical interventions. Human pluripotent stem-cell derived neurons (hPSC-Ns) allow studies against a human genetic background, and show altered morphology and electrophysiology in ASD conditions. However, identifying mechanisms remains difficult with small numbers of lines, especially for common genetic variants. To overcome this challenge, we will leverage multi-omic characterization of hPSC-Ns perturbed with CRISPRi knockdown of both large effect size ASD risk genes and genes related to neuronal morphology (Aim 1) and electrophysiology (Aim 2). We will complement these screens with a characterization (Aim 3) of a larger, diverse cohort of 46 ASD lines and 46 matched controls which do not harbor coding variants in the genes perturbed in the previous Aims. An integrative analysis of this data (Aim 4) will generate interpretable genetic signatures related to each of these phenotypes and will show how these signatures interact with ASD risk genes. This approach is made possible by new techniques for pooled stem cell culture developed in Dr. Ralda Nehme’s lab, high content optical profiling methods developed by Dr. Samouil Farhi’s team, and data integration tools developed by Dr. Ernest Fraenkel’s group. The overall project will provide a basic neurobiological understanding of hPSC-Ns; provide valuable insight into how both common and rare variants induce observed cell-intrinsic phenotypes; and define an analytic framework and genetic signatures which can be used to understand mechanistic recruitment of new genetic risk loci and other psychiatric diseases.