同卵双生的界限型婴儿重症肌阵挛癫痫患者中的钠通道α1基因新突变

De novo sodium channel α1-subunit mutation of monozygotic twins with borderland severe myoelonic epilepsy in infancy

目的筛查一对同卵双胞胎界限型婴儿重症肌阵挛癫痫（borderland severe myoclonic epilepsy of infancy，SMEB）患儿的钠通道α1（sodium channel α1-subunit，SCN1A）基因并探讨其临床特性。方法总结这对同卵双生子患者的临床特点，应用变性高效液相色谱（denaturing high performance liquid chromatography，DHPLC）技术筛查SCN1A基因全部26个外显子，对发现有异常洗脱峰者再进行直接测序。结果这对孪生姐妹患者均具有典型SMEB的临床特点，她们在SCN1A基因第26号外显子被发现有相同的杂合突变（c．5348C〉T），并导致编码的氨基酸改变（A1783E），为国际上首次发现该位点突变。结论临床表型相似的SMEB同卵双胞胎存在相同位点的SCN1A基因突变，证实SMEB与婴儿重症肌阵挛癫痫同样是基因异常引起的疾病，而且基因与临床表型密切相关。

Objective To study the sodium channel α1-subunit （SCN1A） gene in a pair of monozygotic twins with borderland severe myoclonic epilepsy in infancy （SMEB） and its characteristic of clinical manifestations. Methods The clinical features of 2 monozygotic twins were summarized. All 26 exons of SCN1A genes were screened with denaturing high performance liquid chromatography （DHPLC） , and direct sequence analysis was performed on those with abnormal elution peak. Results The proband and her sister showed typical clinical features of SMEB. The same heterozygous mutations on exon 26 which caused the related amino acid change were found among them （c. 5348C 〉 T, A1783E）. Conclusion Monozygotic twins with similar clinical phenotype of SMEB have same SCN1A gene mutation.