A Novel Mutation of Mitochondrial T14709C Causes Myoclonic Epilepsy with Ragged Red Fibers Syndrome in a Chinese Patient / 中华医学杂志(英文版)

<p><b>Background</b>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 (tRNA) 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.</p><p><b>Methods</b>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.</p><p><b>Results</b>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.</p><p><b>Conclusion</b>We present a sporadic patient with typical MERRF presentation carrying the mutation of m.T14709C, which expanded the spectrum of m.T14709C.</p>

Antimyoclonic Effect of Levetiracetam and Clonazepam Combined Treatment on Myoclonic Epilepsy with Ragged-Red Fiber Syndrome with m.8344A>G Mutation / 中华医学杂志(英文版)

<p><b>Background</b>Treatment of myoclonic seizures in myoclonic epilepsy with ragged-red fibers (MERRFs) has been empirical and ineffective. Guideline on this disease is not available. Additional trials must be conducted to find more suitable treatments for it. In this study, the antimyoclonic effects of monotherapies, including levetiracetam (LEV), clonazepam (CZP), valproic acid (VPA), and topiramate (TPM) compared to combination therapy group with LEV and CZP on MERRF, were evaluated to find a more advantageous approach on the treatment of myoclonic seizures.</p><p><b>Methods</b>Treatments of myoclonic seizures with VPA, LEV, CZP, and TPM were reported as monotherapies in 17 MERRF patients from Qilu Hospital between 2003 and 2016, who were diagnosed through clinical data and genetic testing. After 1-4 months of follow-up (mean: 82.9 ± 28.1 days), 12 patients that exhibited poor responses to monotherapy were given a combined treatment consisting of LEV and CZP subsequently. The follow-up period was 4-144 months (mean: 66.3 ± 45.3 months), the effective rates of monotherapy group (17 patients) and combination therapy group (12 patients) were analyzed by Chi-square test.</p><p><b>Results</b>The m.8344 A>G mutation was detected in all patients. There were four patients with partial response (4/17, two in the CZP group and two in the LEV group), ten patients with stable disease (10/17, six in the CZP group, three in the LEV group, and one in the TPM group), and three patients with progressive disease (3/18, two in the VPA group and one in the TPM group). Twelve of the patients with LEV combined with CZP showed a positive effect and good tolerance (12/12), eight of them demonstrated improved cognition and coordination. There was a significant difference between the monotherapy group and combination therapy group in the efficacy of antimyoclonic seizures (χ = 13.7, P < 0.001).</p><p><b>Conclusions</b>LEV in combination with CZP is an efficient and safe treatment for myoclonic seizures in patients with this disease exhibiting the m.8344A>G mutation.</p>

Construction of model for cardiomyocyte disease MERRF using patient-derived iPSC / 临床检验杂志

Objective To obtain myoclonic epilepsy with ragged-red fibers (MERRF)-specific cardiomyocytes by the differentiation in vitro of inducing pluripotent stem cells (iPSC) derived from a MERRF patient and evaluate the application of the prepared cardiomyocytes in construction of MERRF syndrome model.Methods The patient-derived iPSCs and H9 embryonic stem (ES) cells,the control cell line,were unidirectionally differentiated into cardiomyocytes n in vitro.The obtained cardiomyocytes were identified and validated by detecting the presence of cardiomyocyte-specific markers using immunofluorescence staining and RT-PCR.The beating frequencies were recorded to compare the functional evaluation for the two groups of cardiomyocyte.Results Both the patient-derived iPSC and H9 ES cells were differentiated into cardiomyocytes successfully.The average beating frequencies of MERRF-induced cardiomyocytes (iCMs) were 13,24,15 and 18 times/min on the day 10,13,15 and 16 during the cell differentiation process.The average beating frequencies of H9-iCMs were 80,96,120 and 120 times/min,respectively.The beating ability of iPSC-differentiated cardiomyocytes was significantly lower than that of corresponding control (all P ＜ 0.05).Conclusion The patient-derived iPSCs may differentiated into cardiomyocytes.Based on the functional evaluation for these cardiomyocytes,the model for MERRF syndrome with mitochondrial mutations was generated and characterized in vitro.