Recently, we assessed the presence of pupillary abnormalities in a mouse model of cyclin-dependent kinase-like 5 (Cdkl5) deficiency disorder (CDD), a severe neurodevelopmental disorder characterized by early-onset seizures, intellectual disability, motor and cortical visual impairment (Weaving et al., 2004; Moseley et al., 2012). Here, CDKL5 is linked to neurodevelopmental disorder.