The CDKL5 gene encodes a serine/threonine protein kinase that is highly expressed in the brain, mediates phosphorylation of MECP2, and is associated with variable clinical phenotypes.19, 20, 21CDKL5-related disorders are X-linked dominant and often result in male lethality or, less commonly, in a severe phenotype with early-onset epileptic encephalopathy and intellectual disability. The gene discussed is MECP2; the disease is genetic developmental and epileptic encephalopathy.