CDKL5 and craniodiaphyseal dysplasia: Previous studies have shown that Cdkl5 knockout (KO) mice recapitulate many features of CDD, exhibiting severe neuronal impairment leading to deficits in learning, memory and social behaviour (Fuchs et al., 2018; Ren et al., 2019; Tang et al., 2017; Wang et al., 2012).