In one case series of 10 patients with CDKL5 mutations, all (100%) patients had “autistic features” in addition to epilepsy, though the cohort was enriched for patients with early-onset epileptic encephalopathy and/or a clinical diagnosis of Rett syndrome with negative MECP2 sequencing [27]. This evidence concerns the gene CDKL5 and Epileptic encephalopathy.