The relationship between gene mutation types and clinical phenotypes in Dravet syndrome

Abstract

Objective To investigate the relationship between different types of gene mutations and clinical phenotypes in Dravet syndrome. Methods The clinical data of three patients with different types of gene mutations were analyzed retrospectively to illustrate the heterogeneity between gene mutation types and phenotypes in typical and atypical Dravet syndrome.Relevant literatures about the different types of gene mutations in Dravet syndrome and their corresponding clinical features were reviewed. Results The first patient suffered from a very typical manifestation of Dravet syndrome, such as heat sensitivity, mental retardation, the onset time gradually extended, epileptic status, resistance to a variety of antiepileptic drugs, with a new sodium channel α1 gene (SCN1A) mutation which indicated its pathogenicity.The second patient was with some atypical characteristics of Dravet syndrome, such as no febrile seizure, short episodes of attack, mild mental development only showing the language or social retardation.He carried a rare γ-aminobutyric acid receptor subunit (GABRA6) mutation.The third patient had CHD2 gene mutation with the typical myoclonus performance, but didn′t manifest the absence of seizure generalized tonic-clonic seizure and status epilepticus, with dysphonia as the main performance of the movement retardation. Conclusion The phenotypic differences of Dravet syndrome in typical mutations other than SCN1A is very common , and the definition of Dravet syndrome should be more broad spectrum series. Key words: Dravet syndrome; Epilepsy encephalopathy; Gene; Mutation