Probing neuropsychiatric disorders through in vivo CRISPR screening

Although there are many known risk alleles associated with adult-onset psychiatric disorders such as schizophrenia [1-4], bipolar disorder [5-7], and major depressive disorder [8-10], the mechanistic links between these risk alleles and disease pathology, especially on a circuit-level, remain unclear. In vivo pooled CRISPR screening with single‑cell readout (in vivo Perturb‑seq) has begun to fill this gap by mapping causal genes to defined cell states directly in animal tissues [11-14]. Here, we review recent developments and applications of in vivo Perturb-seq in the mouse brain and highlight the potential of utilizing human cellular systems to extend these approaches. Additionally, we discuss how in vivo Perturb-seq can couple genetic perturbation with physiological or environmental perturbations to better model psychiatric diseases with environmental triggers.