Background: Myoclonic epilepsy with ragged red fibers (MERRF) syndrome is characterized by myoclonus, generalized epilepsy, cerebellar ataxia, and ragged red fibers (RRFs) in the muscle. T-to-C transition at nucleotide position 14709 in the mitochondrial tRNA glutamic acid (tRNAGlu) gene has previously been associated with maternally inherited diabetes and deafness. However, the association between MERRF and mitochondrial T14709C mutation (m.T14709C) has never been reported before.
Methods: Clinical information of a 17-year-old patient was collected; muscle biopsy and next-generation sequencing (NGS) of whole mitochondrial and neuromuscular disease panel were then conducted. Finally, sanger sequencing was carried out to confirm the mutations.
Results: The patient presented a typical MERRF phenotype with muscle weakness, epileptic seizure, clonic episodes, cerebellar ataxia, and spinal scoliosis. Muscle biopsy showed RRFs which indicated abnormal mitochondrial functions. NGS of whole mitochondrial gene revealed m.T14709C mutation, confirmed by Sanger sequencing.
Conclusion: We present a sporadic patient with typical MERRF presentation carrying the mutation of m.T14709C, which expanded the spectrum of m.T14709C.
一例中国肌阵挛性癫痫伴碎红纤维（MERRF）患者的新发线粒体基因T14709C点突变摘要背景：肌阵挛性癫痫伴碎红纤维（MERRF）综合征以肌阵挛、癫痫发作、小脑共济失调和肌活检发现破碎红纤维为主要特征。线粒体tRNAGlu基因14709位碱基的T到C突变（m.T14709C）此前报道与母系遗传性糖尿病与耳聋（MIDD）有关。但MERRF 与线粒体基因14709位碱基（m.T14709C）突变相关性未见报道。 方法：收集患者临床表现、肌活检表现和二代测序（全线粒体基因组和神经肌肉病靶向芯片）结果，并用Sanger测序来y验证点突变。 结果：患者表现为典型的MERRF表型，即肌无力、癫痫发作、肌阵挛、小脑共济失调伴有脊柱侧弯。肌活检可见破碎红纤维（RRF），提示线粒体功能异常。线粒体全基因组二代测序检出m.T14709C点突变，并由Sanger测序验证。 结论：报道一例典型MERRF表现的患者携带m.T14709C点突变，从而扩展了m.T14709C的临床表现谱系。.
Keywords: Myoclonic Epilepsy with Ragged Red Fibers Syndrome; Novel Mutation; m.T14709C.