Study Of The Relationship Of SCN1A Genotype,Clinical Phenotype And The Effect Of Treatment In Severe Myoclonic Epilepsy In Infancy

【Objective】To screen SCN1A gene in severe myoclonic in infanct , to study the relationship of SCN1A genotype,clinical phenotype and the effect of treatment , and explore the possible factors leading to severe myoclonic epilepsy in infanct.【Subjects and methods】36 patients were diagnosed with severe myoclonic epilepsy in infancy (SME) according to criteria of the International League against Epilepsy (ILAE) in 2001.The clinical information and blood of the patients and their relatives who had FS or epilepsy history were collected. Blood genome DNA were extracted, all 26 exons of SCN1A gene were PCR amplified and screened with denaturing high performance liquid chromatography(DHPLC)technology, and then sequence analysis was performed.【Result】The blood sample of 36 SME patients and their relatives were collected, 4 patients were lost. 36 SME patients inclulding 25 SMEI and 11 SMEB,28 male and 8 female.14 SME patients had FS or epliepsy family history. All patients had multiple seizure types, generalized seizures included tonic-clonic, myoclonic, absence, tonic and atonic seizures and partial seizures.Some of the patients had ataxia and pyramidal symptoms. VPA, TPM and CNZ were the most effective medicines, LTG and CBZ aggravated in most of patients. 11 exon mutations were found out in screening of SCN1A genes among these patients.Three of them were inherited mutations. 10 patients were found mutations in 5'-untranslated and promoter region among these patients in our previous study. These 36 patients were divided into three groups, exon mutation group,promoter mutation group and without mutation group.The clinical phenotypes of all patients were the same before treating, the effect of treatment and the prognosis of exon group were serious than other groups .【Conclusion】SCN1A is the pathogenic gene for SME. Different mutation type and mutation site have important impact on the clinical phenotype of SME. The same mutation of SCN1A gene can be related to different clinical phenotypes in inherited SME families.If the relatives of SME patients have mild epilepsy or FS, even some of them have no clinical manifestations, we can not excluded the possibility that the pathogenic gene inherited from their relatives. It is probable that other factors have effect on sodium channel and lead to SME except SCN1A.