Cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) is a rare encephalopathy characterized by early-onset intractable epileptic seizures, severe intellectual disability, gross motor impairment, stereotypies, visual impairments and autistic-like features (Kalscheuer et al., 2003; Weaving et al., 2004; Bahi-Buisson et al., 2008; Bahi-Buisson and Bienvenu, 2012; Moseley et al., 2012; Paine et al., 2012; Stalpers et al., 2012; Fehr et al., 2013). The gene discussed is CDKL5; the disease is craniodiaphyseal dysplasia.