Abstract: AbstractObjective: To explore the clinical and genetic features of CDKL5 disorder.Methods: Using the next genomic sequencing technology to detect 7 cases of unexplained early infantile epileptic encephalopathy diagnosed by Xiangya Hospital of Central South University from the year 2011 to 2017,the clinical and molecular features of 7 cases with CDKL5 mutations were summarized ,and the related literatures were reviewed. Results: Five females and two males were diagnosed as CDKL5 disorder.Before the genetic tests,four patients were diagnosed as west syndrome and the other three patients were diagnosed as unclassified early onset epilepsy encephalopathy. The median age of seizure onset was 2 months,and the epilepsy started with partial seizure or tonic seizure,then turned into spasm or myoclonus.The EEG findings in five patients indicated hypsarrhythmia.Seven mutations of CDKL5 were found in seven patients,including three missenses mutations(c.464G>A / p．G134P、c.58G>C / p．G20R、c.464G>A / p．G155D),four frameshift mutations(c.1110del C / p．E370fs、c.160-163del / p．K54fs,c.278dupA / p．E93fs,heterozygous large deletion of the exon 3-8).All the mutations were not found in the parents.The median follow-up time was 36 months,the epileptic seizure of all patients could not be controlled.The number of antiepileptic drugs used ranged from 1 to 8.Four cases underwent the ACTH therapy but didn't get remarkable progress, five cases received ketogenic diet and only two of them achieved a little.All the patients had psychomotor develpoment retardation.Conclusion: CDKL5 disorder is a newly defined central nervous system syndrome caused by CDKL5 mutation,patients with different mutations have different phenotypes and prognosis.