CDKL5 and craniodiaphyseal dysplasia: To date, several different mutations have been described in the CDKL5 gene, mainly located within the CDKL5 catalytic domain (Kilstrup-Nielsen et al., 2012; Das et al., 2013; Fehr et al., 2013), suggesting that impaired CDKL5 kinase activity plays an important role in the pathogenesis of CDD (Tao et al., 2004; Bahi-Buisson et al., 2012).