We therefore generated Msx2 knockout lines (Msx2164fs/+ and Msx2165fs/+) carrying c.491_492insC and c.492_493insA truncations by frameshift (p.K164fs and p.Q165fs, respectively), mimicking the p.A173fs variant in the patient with NDD and partial epilepsy (Fig. S8A and B) and investigated whether these mice show NDD‐like phenotypes. The gene discussed is MSX2; the disease is Neurodevelopmental delay.