Modeling patient variants of Cnot1 and Cdc42bpb lead to distinct forms of congenital diaphragmatic hernia in mice

Each gene was found to have a damaging, de novo missense variant in a recent large-scale CDH patient sequencing screen. Loss of Cdc42bpb leads to ventral diaphragmatic hernia, heart septal defects and minor lung epithelial differentiation defects in mouse embryos. Installation of the orthologous patient missense variant through CRISPR/Cas9 editing leads to less severe ventral diaphragm defects.

Mouse embryos with either one or two copies of the orthologous Cnot1 variant, c.1867C>T (p.R623W), develop dorsal diaphragmatic hernias with low (<50%) penetrance, and mutants showed alterations in mRNA isoform expression consistent with the molecular role of Cnot1 in RNA splicing. Taken together, these results underscore the power of in vivo functional modeling and reveal two previously unrecognized genetic drivers of diaphragm development and CDH pathogenesis.