CDKL5 and Intellectual disability: Dozens of mutations of the CDKL5 gene are causative of CDKL5 Deficiency Disorder (CDD; OMIM 300203; 300672) [1, 2], a severe condition that is manifested with intellectual disability, autistic behavior, motor and visual impairments, infantile-onset refractory epilepsy, and many other symptoms [3].