Cyclin-dependent kinase-like 5 (CDKL5, OMIM:300203, 300672) deficiency disorder (CDD, OMIM #300203) is a rare encephalopathy that affects between 1:40 000 to 1:60 000 newborns, with females making up about 90 percent of diagnosed patients [1,2]. The gene discussed is CDKL5; the disease is craniodiaphyseal dysplasia.