Mitochondrial encephalopathy, lactic acidosis and stroke-like episodes / myoclonus epilepsy with ragged-red fibers /Leigh overlap syndrome caused by mitochondrial DNA 8344A>G mutation / 北京大学学报(医学版)

OBJECTIVE@#Mitochondrial deoxyribonucleic acid (mtDNA) 8344 A>G (m.8344A>G) mutation is the common mutation associated with mitochondrial myoclonus epilepsy with ragged-red fibers (MERRF) syndrome. Herein we report a rare case with mitochondrial encephalopathy, lactic acidosis and stroke-like episodes/MERRF/Leigh (MELAS/MERRF/Leigh) overlap syndrome caused by m.8344A>G mutation.@*METHODS@#The clinical and imaging data of the patient were collected and an open muscle biopsy was carried out. We further employed molecular genetic analyses to detect mtDNA mutation in the proband and his mother. And then a clinical and neuroimaging follow-up was performed.@*RESULTS@#This patient was a 25-year-old male, who developed exercise intolerance since the age of 6. At age 10, he suffered from acute episodes of hemianopia, and cranial magnetic resonance imaging (MRI) showed occipital stroke-like lesions and cranial magnetic resonance spectroscopy (MRS) revealed a lactate peak corresponding to the lesion. After that the patient presented slowly progressive psychomotor decline. He had myoclonic seizures and cerebellar ataxia since the age of 12. At age 21, he was admitted to our hospital because of confusion and cranial MRI revealed symmetrical lesions in bilateral posterior putamen, thalami and midbrain. Then repeated MRI showed progression of original lesions and new frontal multiple stroke-like lesions. Symptomatic and rehabilitation treatment relieved his condition. Follow-up cranial MRI at age 24 showed the lesions in basal ganglia and thalami diminished, and the midbrain lesions even completely vanished. Muscle pathology indicated the presence of numerous scattered ragged-red fibers (RRF), suggestive of a mitochondrial disorder. Polymerase chain reaction-restricted fragment length polymorphism (PCR-RFLP) detected the m.8344A>G mutation of the MT-TK gene encoding mitochondrial transfer RNA for lysine in the patient's blood. Next generation sequencing (NGS) of the whole mitochondrial genome identified that the proportion of m.8344A>G was 90%, and no other mtDNA mutation was detected. Sanger sequencing further identified this mutation both in the proband and his mother's blood, although the mutation load was much lower in his mother's blood with approximately 10% heteroplasmy.@*CONCLUSION@#The present study is the first to describe a patient with m.8344A>G mutation in association with the MELAS/MERRF/Leigh overlap syndrome, which expands the phenotypic spectrum of the m.8344A>G mutation.

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.

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>

Mitochondrial diseases with the main manifestations of cardiomyopathy and respiratory muscle damage / 中华实用儿科临床杂志

Objective The 3243A ＞ G mutation in mitochondrial DNA is a common cause of the classical mitochondrial diseases characterized by neuro-muscular disorders.This study reports a rare case with the main manifestations of mitochondrial disease in children of mitochondrial cardiomyopathy and respiratory muscle damage.Methods The clinical characteristics,diagnosis and treatment,biochemical,pathological and genetic features of a 10-year-old girl were studied.Results The girl was admitted because of heart failure and respiratory failure at the age of 10.Ragged red fibers in skeletal muscles had been noticed.On her mitochondrial gene,3243A ＞ G mutation,Leu tRNA (UUR),was detected.The mutation rate in the peripheral blood cells was 94％.After the treatment with a high dose of creatine phosphate sodium,coenzyme Q10 and L-carnitine with assisted ventilation,the patient improved rapidly.The child was followed up for 2 years without recurrence.Meanwhile the growth,development and daily life were normal.Conclusions Cardiac and respiratory muscle impairments that appeared at the same time as the first manifestations of the children's mitochondrial disease is not common,and it is rare to have cardiomyopathy based mitochondrial gene 3243A ＞ G mutation is seldom seen clinically.Skeletal muscle biopsy and genetic test is the key for accurate diagnosis.Improving mitochondrial metabolism and assisted ventilation appear to be helpful treatments.

Síndrome de Kearns-Sayre, presentación de un caso clínico / Kearns-Sayre Syndrome

El síndrome de Kearns Sayre es una mitocondriopatía caracterizada por disfunciones multiorgánicas que clásicamente se desarrolla antes de los veinte años de edad. Esta rara enfermedad fue descrita en 1958 por Thomas P. Kearns y George P. Sayre a través del reporte de un caso que representaba la triada clínica de oftalmoplejia externa, retinopatía pigmentaria y bloqueos de la conducción cardíaca; siendo esta última alteración la que determina el pronóstico. Aún no se cuenta con un tratamiento curativo para esta enfermedad. En este artículo presentamos el caso clínico de una paciente de 39 años a la que se realizó el diagnóstico de Kearns-Sayre.

Aspectos morfológicos de biópsias musculares em equinos com miopatia sob forma de surto / Morphological features of muscle biopsies from horses of a myopathy outbreak

As miopatias em equinos são classificadas de acordo com aspectos clínicos, morfológicos e moleculares, em três grandes grupos: não associadas ao exercício, associadas ao exercício e devido alteração da condução elétrica do sarcolema. Apesar dos avanços no diagnóstico, a literatura ainda relata surtos de miopatia em equinos sem etiologia esclarecida em diversos países. O objetivo desse estudo foi descrever as alterações histológicas e histoquímicas de biópsias musculares de equinos acometidos por miopatia. Sete equinos da raça Quarto de Milha, com 18-24 meses de idade, apresentaram sinais clínicos de miopatia. Dentre esses animais, cinco apresentaram sinais subagudos leves a moderados e dois apresentaram sinais hiperagudos severos e decúbito lateral. Foram realizadas biópsias musculares utilizando a técnica percutânea, por agulha tipo Bergström, no músculo glúteo médio em todos os animais acometidos. As amostras foram processadas por meio de técnicas histológicas (HE, Tricrômio de Gomori modificado) e histoquímicas (PAS, NADH, ATPase). Nos quadros clínicos mais leves, a principal alteração encontrada foi a presença de fibras vermelhas rajadas do tipo I e IIA, que estão associadas às alterações do metabolismo oxidativo e das funções mitocondriais, como ocorrem nas miopatias mitocondriais. Também foram observadas fibras atróficas do tipo I e IIA, além da presença de agregados subsarcolemais. Nos quadros mais severos o tecido muscular apresentou infiltrado inflamatório, aumento de colágeno, fagocitose, necrose, calcificação e regeneração muscular. Diante dos achados morfológicos, da resposta à terapia com vitamina E e Se e da baixa mortalidade quando comparado aos relatos de miopatia atípica, conclui-se que esse surto foi desencadeado por lesões mitocondriais, caracterizadas pelas fibras musculares vermelhas rajadas, possivelmente devido uma quebra da homeostase de vitamina E e Se, sendo compatível com o diagnóstico de miopatia nutricional.

Equine myopathies are classified according clinic, morphologic and molecular features in three groups: Non-exertional, exertional, and abnormal muscle membrane conduction. In spite the advances in diagnostic, the literature has reported outbreaks of equine myopathy without clear etiology in several countries. The aim of this study was to describe the histological and histochemical findings of muscle biopsies in an outbreak of equine myopathy. Seven 18 to 24-month-old Quarter horses showed clinical signs of myopathy. Five horses presented mild clinical signs and two horses had severe clinical signs with recumbency. Muscle biopsies were obtained from gluteal medium muscle by percutaneous technique with Bergstrom needle in all affected horses. Muscle samples were processed by histological (HE, modified gomori-trichrome) and histochemical (PAS, NADH, ATPase) technics. In animals with mild clinical signs, ragged red fibers type I and IIA, related to the oxidative metabolism dysfunction of mitochondria, was the main abnormality found. Muscle fiber atrophy and presence of subsarcolemmal aggregates in type I and IIA muscle fibers were also observed. More severe affected horses presented inflammatory infiltrate, proliferation of collagen, phagocytosis, necrosis and calcification. Based on the morphological findings, vitamin E therapy response associated with the low mortality when compared with atypical myopathy reports, We concluded that this outbreak was triggering for mitochondrial lesions, characterized by ragged red muscle fibers, probably due a breakdown homeostasis in vitamin E and Se, being compatible with nutritional myopathy diagnosis.

Dysferlinopathy: Spectrum of pathological changes in skeletal muscle tissue.

Background: Dysferlinopathy is an autosomal recessive-limb girdle muscular dystrophy (AR-LGMD) caused due to the defect in gene encoding dysferlin, a sarcolemmal protein. Awareness of the variants and their relative frequency is essential for accurate diagnosis. Aim: To study the spectrum of morphologic changes in immunohistochemically proven cases of dysferlinopathies, to correlate the findings with clinical phenotype and durations of illness and determine the frequency. Materials and Methods: Dysferlinopathies seen over a period of 2 years at a tertiary neurological center were analyzed. Results: Clinically, majority had Miyoshi phenotype (46.6%) with distal involvement and LGMD phenotype (40%) with proximal muscle involvement. In addition, a proximo-distal and tibial muscle phenotype was encountered. Morphologically, rimmed vacuoles were noted in the Miyoshi phenotype. The presence of ragged red fibers, lobulated fibers and inflammation had no preference to a particular phenotype. Significant atrophy and lobulated fibers were noted in patients with longer duration of illness. Conclusions: Dysferlinopathy was the second most common identifiable cause (21%) of LGMD next to sarcoglycanopathies (27%).

Kearns-Sayre Syndrome: 3 Case Reports and Review of Clinical Feature

Kearns-Sayre syndrome, first described by Kearns and Sayre in 1958, is a rare disorder consisting of ptosis, limited movement of both eyes and atypical retinal pigmentary change (salt-pepper like appearance). Most cases have shown an increase in the concentration of mitochondria and ragged-red fiber under Gomori-trichrome staining on muscle biopsy. Occasionally, it is combined with other neurologic and endocrinologic symptoms such as ataxia, dementia, diabetes, and hyperaldosteronism. We recently experienced three cases of male teenaged patients who expressed the clinical features of Kearns-Sayre syndrome.

A Case of Rhabdomyolysis and Acute Renal Failure Associated with Mitochondrial Myopathy / 대한신장학회잡지

Mitochondrial myopathies are diseases caused by defects in metabolic pathway of mitochondria. Mitochondrial myopathy is known as one of the causes of recurrent myoglobinuria, while clinically, rarely causes acute renal failure requiring medical treatments. We report a case of rhabdomyolysis and acute renal failure associated with mitochondrial myopathy. A 58-year-old male was presented with dyspnea and hypotensive shock. The patient had a history of recurrent dark colored urine and cramping leg pain after prolonged fasting. Laboratory findings showed hyperkalemia, azotemia, metabolic acidosis, and elevated AST, ALT, and creatinine kinase. He had no history of trauma or medication. Muscle biopsy showed "ragged red fibers" in modified Gomori staining. On electron microscope, increased number of mitochondria and abnormal mitochondria were seen. He received hemodialysis and his renal function recovered after 1 month.

Pathologic Findings of Mitochondrial Myopathy

Mitochondrial myopathy (MM) has been applied to muscle disease in which mitochondria have abnormal structure, function or both. To characterize the pathologic findings of MM, we examined the ultrastructural and histochemical findings of 24 cases of MM. The ultrastructures of the MM were characterized by abnormal mitochondria in number (pleoconia) and size (megaconia), and showed predominant accumulation of mitochondria in the subsarcolemmal space of myofibers in all cases. Mitochondria contained abnormally shaped cristae (concentric form and gyriform) in 79% of cases. Paracrystalline inclusion which was known to be a characteristics of MM were seen only in 7 cases (29%). Electron dense deposits were more frequently found (77%) in abnormal mitochondria of chronic progressive external opthalmoplegia and Kearn-Sayre syndrome. But, other findings were not specific for the specific clinical entities. On succinate dehydrogenase (SDH) stain, ragged red fibers (RRF) showed more intense positivity than modified Gomori-trichrome stain and definite strong reactive products were present along the periphery of myofibers which showed normal findings on modified Gomori-trichrome stain. In conclusion, ultrastructural findings such as mitochondria showing pleoconia with megaconia, and bizarre shaped cristae may be helpful for the diagnosis of MM and SDH stain is more useful for identification of RRF than modified Gomori-trichrome stains.

Enzyme histochemical study of germanium dioxide-induced mitochondrial myopathy in rats

The purpose of this study were 1) to determine the earliest pathological changes of germanium dioxide (GeO2)-induced myopathy; 2) to determine the pathomechanism of GeO2-induced myopathy; and 3) to determine the minimal dose of GeO2 to induce myopathy in rats. One hundred and twenty five male and female Sprague-Dawley rats, each weighing about 150 gm, were divided into seven groups according to daily doses of GeO2. Within each group, histopathological studies were done at 4, 8, 16, and 24 weeks of GeO2 administration. Characteristic mitochondrial myopathy was induced in the groups treated daily with 10 mg/kg of GeO2 or more. In conclusion, the results were as follows: 1) The earliest pathological change on electron microscope was the abnormalities of mitochondrial shape, size and increased number of mitochondria; 2) The earliest pathological change on light microscope was the presence of ragged red fibers which showed enhanced subsarcolemmal succinate dehydrogenase and cytochrome c oxidase reactivity; 3) GeO2 seemed to affect the mitochondrial oxidative metabolism of muscle fibers; 4) GeO2 could induce mitochondrial myopathy with 10 mg/kg of GeO2 for 4 weeks or less duration in rats.

A Case of Kearns-Sayre Syudrome

Kearns-Sayer syndrome, a rare mitochondrial disorder, is composed of chronic progressive external ophthalmoplegia, atypical retinal pigmentation and complete heart block, and also causes numerous neurologic or endocrinologic symptoms. On muscle biopsy, a "ragged red fiber" was seen with Gomori trichrome stain, On electron microscopy, aggregations of abnormal mitochondria were demonstrated, confirming the diagnosis of mitochondrial myopathy. We report a case of Kearns-Sayer syndrome we have experienced.

A Case of Chronic Progressive External Ophthalmoplegia

Chronic progressive external ophthalmoplegia(CPEO) is rare syndrome, which is characterized by slowly progressive blepharoptosis, paralysis of extraocular muscle and has involvement of other organs, particularly the retina, heart, endocrine gland, and bony skeleton. Histological examination of muscle showes characteristic ragged red fibers. Electron microscopy reveals a number of abnormal mitochondria which contain paracrystalline inclusion bodies. We experienced a 50-year-old female with CPEO, that was pathologically proven by electron microscopy and bilateral levator levator advancements were given for ptosis.

Clinical Manifestations of Mitochondrial Diseases

According to the recently published reports about mitochondrial diseasbl the clinical manifestations are more various than expected. There have been no clinical studies covering whole spectrum of mitochond7iral disease except a few case reports in our country. The authors performed this studies to understand the various clinical and laboratory findings of mitochondrial disease and the usefulness of current tools for the diagnosis of mitochondrial diseases. We reviewed retrospectively the clinical, laboratory and pathologic findings of mitochondrial disease. The diagnosis of mitochondrial disease was based on clinical manifestations, 'ragged-red fiber' in Gomori stainging, and/or abnormal mitochondrial morphologies on electron microscopy. Twenty one patients were diagnosed as mitochondrial disease. Their clinical diagnosis included 7 MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes); 3 MERRF (myoclonic epilepsy with ragged red fibers); 2 KSS (Kearns-Sayre syndrome); 7 CPEO (chronic progressive external ophthalmoplegia); and 2 mitochondrial myopathy. The usefulness of electrodiagnostic studies, such as EMG, NCV and FEG, were limited in some patients. The muscle biopsy showed ragged red fibers in 10 of 15 sampled examined. Eleven patients had abnormal serum lactic acid level. The authors found that the mitochondrial disease revealed broad clinical spectrum and clinically available diagnostic tests, such as serum lactate and light microscopic examination showed limited value. Therefore, to evaluate the mitochondrial dysfunction with systemic involvement may be desirable to depend on sensitive and specific methods including succinate dehydrogenase (SDH) staining, electron microscopy and biologic studies of mitochondrial DNA.

A case of MELAS syndrome

MELAS syndrome is a rare but distinct clinical entity belonging to a group of mitochondrial encephalomyopathies characterized by the tetrad of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes. We experienced a case of MELAS syndrome in an 8 year-old boy who showed headache, pain of the eyeball, vomiting, stroke-like episodes such as visual disturbance and dysarthria, myoclonic seizure, confusion, and walking disturbance. His serum lactate level was elevated up to 48 mg/dl. MRI findings showed high signal intensities T2-weighted image and low signal intensities in T1-weighted image in the right thalamus and parietooccipital lobe and bilateral symmetric high signal intensity in T1-dweighted image in the basal ganglia. We have seen the dispersed ragged-red fibers with modified Gomori trichrome staining on light microscope, and abundant and dysmorphic mitochondria on electon microscope in the specimen of muscle biopsy. esis of SLE.

Clinical and pathological characteristics of pure type mitochondrial myopathy / 临床神经病学杂志

Objective To investigate the clinical and pathological features of pure type mitochondrial myopathy.Methods Clinical manifestations and pathological features of biopsied muscle specimens were summarized retrospectively in 9 cases of pure mitochondrial myopathy. 6 of them were followed up on the purpose of prognostic analysis.Results 9 cases of pure mitochondrial myopathy were clinical characterized by exclusive skeletal muscle involvement and fluctuating proximal muscle weakness. Extraocular muscles were spare. Most patients had moderately increased creatine phosphokinase level (539～2 913U/L). Electromyography examination showed myogenic changes in 6 cases and neurogenic in 3 cases. Pathologically, 8 cases had typical ragged red fibers (RRF) accounting for 5% to 60%. Mitochondrial intracristal inclusion bodies were observed by electron microscope in the patient with atypical RRF. Focal cytochrome C oxidase (COX) deficiency was seen in 4 cases and total deficiency in 2 cases. To a certain degree, the percentage of RRF was parallel to muscle weakness. Following-up data from 6 patients showed that symptoms had improved in 5 patients after treatment with vitamin B, vitamin E, CoQ 10 and inosine. One had a sudden death with unknown reason.Conclusion Pure mitochondrial myopathy may be a distinct subset of mitochondrial diseases that preferentially affects trunk and proximal muscles,Pathological charactoristic had typical RRF and COX deficiency,and RRF is related to patient's condition.It has relative chronic process and benign prognosis.

Chronic progressive external ophthalmoplegia (CPEO) with 'ragged red fibers': a case report

Chronic progressive external ophthalmoplegia (CPEO) is a rare clinical syndrome characterized by slowly progressive paralysis of extraocular muscles. We report a male patient who had a 20 year history of CPEO. Histological examination of left deltoid muscle showed characteristic ragged red fibers. Electron microscopy revealed a number of abnormal mitochondria which contain paracrystalline inclusion bodies.