Modeling MPPH syndrome in vivo using Breasi-CRISPR.

The increasing availability and affordability of genetic testing has resulted in the identification of numerous novel variants associated with neurodevelopmental disorders. There remains a need for methods to analyze the functional impact of these variants. Some methods, like expressing these variants in cell culture, may be rapid, but they lack physiologic context. Other methods, like making a whole-mouse model, may provide physiologic accuracy, but these are costly and time-consuming. We recently developed a technique, Breasi-CRISPR (Brain Easi-CRISPR), which results in efficient genome editing of neural precursor cells via electroporation of CRISPR-Cas9 reagents into developing mouse brains. Since Breasi-CRISPR is extremely rapid and enables the analysis of targeted genes in vivo, we wondered whether this technique would accelerate the study of monogenic neurodevelopmental disorders. Here, we use Breasi-CRISPR to model megalencephaly postaxial polydactyly polymicrogyria hydrocephalus (MPPH) syndrome. We found that 2 days after Breasi-CRISPR, we were able to see neurodevelopmental phenotypes known to be associated with MPPH syndrome, including increased cyclin D2 protein abundance and an increase in neural progenitor proliferation. Thus, Breasi-CRISPR can efficiently model MPPH syndrome and may be a powerful method to add to the toolbox of those investigating the functional impact of patient variants in neurodevelopmental disorders.