A CRISPR-engineered Isogenic Model Reveals Altered Neuronal Phenotypes of the 22q11.2 A-B Syndromic Deletion

The 22q11.2 deletion syndrome (22q11.2DS), associated with congenital and neuropsychiatric anomalies, is the most common copy number variant (CNV)-associated syndrome. Patient-derived, induced pluripotent stem cell (iPS) models have provided important insight into the mechanisms of phenotypic features of this condition. However, patient-derived iPS models may harbor underlying genetic heterogeneity that can confound analysis of pathogenic CNV effects. Furthermore, the [~]1.5 Mb "A-B" deletion at this locus is inherited at higher frequency than the more common [~]3 Mb "A-D" deletion, but remains under-studied due to lack of relevant models. To address these issues, here we leveraged a CRISPR-based strategy in Cas9-expressing iPS cells to engineer novel isogenic models of the 22q11.2 "A-B" deletion. After in vitro differentiation to excitatory neurons, integrated transcriptomic and cell surface proteomics identified deletion-associated alterations in surface adhesion and cell signaling. Furthermore, implantation of iPS-derived neuronal progenitor cells into the cortex of neonatal mice found accelerated neuronal maturation within a relevant microenvironment. Taken together, our results suggest pathogenic mechanisms of the 22q11.2 "A-B" deletion in driving neuronal and neurodevelopmental phenotypes, both in vitro and in vivo. We further propose that the isogenic models generated here will provide a unique resource to study this less-common variant of the 22q11.2 microdeletion syndrome.