Myoclonic Epilepsy with Ragged-red Fibers with Intranuclear Inclusions.

We herein report a case of myoclonic epilepsy with ragged-red fibers (MERRF) harboring a novel variant in mitochondrial cysteine transfer RNA (MT-TC). A 68-year-old woman presented with progressive myoclonic epilepsy with optic atrophy and peripheral neuropathy. A skin biopsy revealed p62-positive intranuclear inclusions. No mutations were found in the causative genes for diseases known to be related to intranuclear inclusions; however, a novel variant in MT-TC was found. The association between intranuclear inclusions and this newly identified MERRF-associated variant is unclear; however, the rare complication of intranuclear inclusions in a patient with typical MERRF symptoms should be noted for future studies.

Lipomatosis and optic neuropathy clinches the diagnosis of myoclonic epilepsy with ragged red fibres (MERRF) syndrome.

We present a rare case of myoclonic epilepsy with ragged red fibres with high level of heteroplasmy presenting with optic neuropathy and a rare phenotype of lipomatosis. Cutaneous lipomas are typically thought of as a benign/isolated entity and this case emphasises importance of considering mitochondrial disease in all patients with lipomatosis especially in the presence of other systemic abnormalities.

Perioperative Management of an Adult Patient With Myoclonic Epilepsy With Ragged Red Fibers Syndrome: A Case Report.

Myoclonic epilepsy with ragged red fibers (MERRF) syndrome is a rare mitochondrial disease potentially associated with increased sensitivity to anesthesia and metabolic decompensation. We present the perioperative management in a 59-year-old man with MERRF scheduled for lipomatosis cure under general anesthesia (GA). Following a reduced fasting period, the patient had an uneventful balanced GA with propofol, sevoflurane, and rocuronium. The patient did not present metabolic decompensation nor malignant hyperthermia but prolonged neuromuscular blockade. Propofol and sevoflurane may be used in asymptomatic MERRF adult patients. Such patients present high risk of residual neuromuscular blockade that should be monitored and reversed.

Diagnosing MERRF requires clinical and genetic evidence.

The interesting case about a patients with myoclonic epilepsy with ragged-red fibers (MERRF) syndrome due to the variant m.8344A>G with a heteroplasmy rate of 95% reported by Felczak et al. expands the phenotypic spectrum of MERRF syndrome. The authors reported a pituitary adenoma, calcium deposits in arterial walls, and an intra-cerebral lipoma in the corpus callosum in their patient. Shortcomings of the study are that the diagnostic criteria for MERRF were not accomplished, that the patient should be rather diagnosed as a mitochondrial, multiorgan disorder syndrome (MIMODS), that no pedigree and heteroplasmy rates in first degree relative were provided, that hormone levels were not provided despite obvious endocrinological involvement, and that no serum or cerebrospinal fluid (CSF) lactate levels were reported.

Ganglionopathies Associated with MERRF Syndrome: An Original Report.

Neuropathies in Myoclonic Epilepsy with Ragged Red Fibers (MERRF) syndrome are frequent but ganglionopathies have never been reported. We retrospectively identified 24 patients with MERRF mutations in the neuromuscular center Nord/Est/Ile de France (Pitié-Salpêtrière, Paris, France). Seventeen nerve conduction studies (NCS) were available. Five patients had MERRF syndrome and ganglionopathy, a pure sensory neuropathy. All of them displayed ataxia and mild clinical sensory abnormalities. Ganglionopathies have been reported in mitochondrial diseases but never in MERRF syndrome. We suggest that patients presenting with ganglionopathy, especially if associated with myopathy, lipomatosis or epilepsy, should be screened for MERRF mutations.

Tumors masquerading as neurological diseases: A caution for clinicians in planning diagnosis and treatment.

INTRODUCTION: Neurological diseases can be due to direct diseases of the central nervous system (CNS) or peripheral nervous system (PNS) or be a bystander syndrome of systemic diseases. Treatment options depend on the cause. Toxic, metabolic and nutritional, and immune-mediated consequences of clinically occult neoplasms produce a spectrum of neurological diseases, recognition of which has therapeutic and prognostic importance. PATIENTS AND METHODS: Children, as well as adults who presented to the authors in the last 5 years with neurological diseases and later their diseases could be diagnosed or attributed to neoplasms which were occult, were included for the study. OBSERVATION: 28 patients were seen by the authors in the last 5 years with neurological manifestation and hidden tumor. Maximum incidence was in the age of above 60 years followed by the age group of 21-40 years. The commonest neurological presentation was muscle and nerve in adults and seizure in children. DISCUSSION: Short duration, rapid progression, severe weight loss, and poor response to treatment given for nontumor associated neurological syndrome are the red flags which point to the diagnosis. CONCLUSION: Seizures and psychosis formed the commonest features in children, muscle and nerve in adults. Short duration, rapid progression, and resistance to treatment are the markers for possible underlying neoplasm.

Self-initiated lifestyle interventions lead to potential insight into an effective, alternative, non-surgical therapy for mitochondrial disease associated multiple symmetric lipomatosis.

BACKGROUND: A 56-year-old female, diagnosed as a carrier of the mitochondrial DNA mutation (MTTK c.8344A > G) associated with the MERRF (myoclonic epilepsy with ragged red fibers) syndrome, presented with a relatively uncommon but well-known phenotypic manifestation: severe multiple symmetric lipomatosis (MSL). After surgical resection of three kilograms of upper mid-back lipomatous tissue, the patient experienced a significant decline in her functional capacity and quality of life, which ultimately resulted in her placement on long-term disability. METHODS: Dissatisfied with the available treatment options centered on additional resection surgeries, given the high probability of lipoma regrowth, the patient independently researched and applied alternative therapies that centred on a carbohydrate-restricted diet and a supervised exercise program. RESULTS: The cumulative effect of her lifestyle interventions resulted in the reversal of her MSL and her previously low quality of life. She met all her personal goals by the one-year mark, including reduced size of the residual post-surgical lipomas, markedly enhanced exercise tolerance, and return to work. She continues to maintain her interventions and to experience positive outcomes at the two-year mark. INTERPRETATION: This case report documents the timing and nature of lifestyle interventions in relation to the reversal in growth pattern of her previously expanding and debilitating lipomas. The profound nature of the apparent benefit on lipoma growth demonstrates the intervention's potential as a new feasible non-surgical therapy for mitochondrial-disease-associated MSL, and justifies its systematic study. We also describe how this case has inspired the care team to re-examine its approach to involved patients.

[Ultrastructural and clinical findings of mitochondrial encephalomyopathy:report of 27 cases].

Objective: To investigate the ultrastructural features of muscle in patients with mitochondrial encephalomyopathy for its diagnosis and differential diagnosis. Methods: The clinical data of 27 mitochondrial encephalomyopathy patients who underwent left or right biceps brachii muscle biopsy at Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University from July 2006 to August 2017 were analyzed retrospectively. The muscle biopsy specimens were examined underlight microscope and transmission electron microscope. Results: There were 27 patients (17 males, 10 females) with an age range of 12 to 62 years (mean 29 years). The age of onset ranged from 3 to 38 years. The course of disease ranged from 1 month to 24 years. Twenty-two cases presented with lactic acidosis and stroke-like episodes (MELAS) syndrome, four with myoclonic epilepsy with ragged red fibers (MERRF) syndrome, and one with chronic progressive paralysis of extraocular muscle (CPEO) syndrome. Skeletal muscle biopsy showed abundant ragged red fibers and strongly SDH-reactive vessel. Genetic studies showed 17 of 22 cases of MELAS syndrome had A3243G mutation, and the other 5 cases had no abnormality. A8344G mutation was found in 3 of 4 cases of MERRF syndrome. No single or multiple mtDNA mutations were found in the single case of CPEO. Transmission electron microscopy of all 27 cases showed diffuse proliferation of mitochondria between the myofibrils and beneath the sarcolemma, with increased spacing between muscle cells. Seven cases showed numerous glycogen and four showed subsarcolemmal lipid droplets, 13 cases showed unusual mitochondrial morphology, including mitochondrial electron-dense substances and paracrystal line inclusions ("parking lot" change)in eight cases. Conclusions: Transmission electron microscopy shows significant differences in ultrastructural pathological changes among different patients with mitochondrial encephalomyopathy. Some patients with mild clinical symptoms have increased mitochondrial number, increased metabolism of glycogen and lipid droplets, while others with severe clinical symptoms have abnormal mitochondrial morphology. Typical crystalloid inclusions are found in mitochondria, which are of great value in the diagnosis of this disease.

MERRF syndrome (Myoclonic Epilepsy with Ragged Red Fibres) presenting with cervicothoracic lipomatosis.

INTRODUCTION: Patients with MERRF syndrome (Myoclonic Epilepsy with Ragged Red Fibres) usually present with encephalomyopathy. However, progressive, recurrent cervicothoracic lipomatosis may be rarely observed. CASE REPORT: The authors report 4 cases of MERRF syndrome associated with lipomatosis. In 3 patients, the diagnosis of MERRF syndrome was established on the basis of the clinical features of the lipomas and clinical interview revealing a personal or family history of lipomas and myopathy. DISCUSSION: In the presence of extensive spinal lipomatosis, the presence of other clinical signs of MERRF syndrome in the patient or the patient's family must be investigated. A diagnosis of MERRF syndrome can guide appropriate genetic counselling.

The Bacterial Protein CNF1 as a Potential Therapeutic Strategy against Mitochondrial Diseases: A Pilot Study.

The Escherichia coli protein toxin cytotoxic necrotizing factor 1 (CNF1), which acts on the Rho GTPases that are key regulators of the actin cytoskeleton, is emerging as a potential therapeutic tool against certain neurological diseases characterized by cellular energy homeostasis impairment. In this brief communication, we show explorative results on the toxin's effect on fibroblasts derived from a patient affected by myoclonic epilepsy with ragged-red fibers (MERRF) that carries a mutation in the m.8344A>G gene of mitochondrial DNA. We found that, in the patient's cells, besides rescuing the wild-type-like mitochondrial morphology, CNF1 administration is able to trigger a significant increase in cellular content of ATP and of the mitochondrial outer membrane marker Tom20. These results were accompanied by a profound F-actin reorganization in MERRF fibroblasts, which is a typical CNF1-induced effect on cell cytoskeleton. These results point at a possible role of the actin organization in preventing or limiting the cell damage due to mitochondrial impairment and at CNF1 treatment as a possible novel strategy against mitochondrial diseases still without cure.

A Novel Mutation of Mitochondrial T14709C Causes Myoclonic Epilepsy with Ragged Red Fibers Syndrome in a Chinese Patient.

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.

CO2-sensitive tRNA modification associated with human mitochondrial disease.

It has been generally thought that tRNA modifications are stable and static, and their frequencies are rarely regulated. N6-threonylcarbamoyladenosine (t6A) occurs at position 37 of five mitochondrial (mt-)tRNA species. We show that YRDC and OSGEPL1 are responsible for t6A37 formation, utilizing L-threonine, ATP, and CO2/bicarbonate as substrates. OSGEPL1-knockout cells exhibit respiratory defects and reduced mitochondrial translation. We find low level of t6A37 in mutant mt-tRNA isolated from the MERRF-like patient's cells, indicating that lack of t6A37 results in pathological consequences. Kinetic measurements of t6A37 formation reveal that the Km value of CO2/bicarbonate is extremely high (31 mM), suggesting that CO2/bicarbonate is a rate-limiting factor for t6A37 formation. Consistent with this, we observe a low frequency of t6A37 in mt-tRNAs isolated from human cells cultured without bicarbonate. These findings indicate that t6A37 is regulated by sensing intracellular CO2/bicarbonate concentration, implying that mitochondrial translation is modulated in a codon-specific manner under physiological conditions.

[Isolated girdle weakness: expansion of the phenotypic spectrum of the MERRF 8344A>G mutation of mitochondrial DNA]. / Debilidad aislada de cinturas: ampliacion del espectro fenotipico de la mutacion MERRF 8344A>G del ADN mitocondrial.

INTRODUCTION: The differential diagnosis of diseases that are accompanied by adult-onset girdle weakness is broad and includes motor neurone, neuromuscular junction or muscular diseases. The 8344A>G mutation of the MTTK gene of mitochondrial DNA usually presents with involvement of multiple organs associated (or not) with girdle weakness. To date no cases of isolated girdle weakness have been reported as the presenting symptom of this mutation. CASE REPORT: A 57-year-old male, with a four-year history of isolated clinical signs of progressive girdle weakness. He is the brother of a 59-year-old woman with the same clinical features. Muscular biopsy played a decisive role in the diagnosis and was characteristic of mitochondrial myopathy. The genetic analysis revealed the 8344A>G mutation of the MTTK gene of mitochondrial DNA. CONCLUSIONS: The 8344A>G mutation of mitochondrial DNA can be associated with clinical signs and symptoms of adult-onset girdle weakness, and must therefore be included as part of its differential diagnosis.

TITLE: Debilidad aislada de cinturas: ampliacion del espectro fenotipico de la mutacion MERRF 8344A>G del ADN mitocondrial.Introduccion. El diagnostico diferencial de los trastornos que cursan con debilidad de cinturas de inicio en la edad adulta es amplio e incluye enfermedades de neurona motora, union neuromuscular o musculo. La mutacion m.8344A>G del gen MTTK del ADN mitocondrial suele presentarse con afectacion de multiples organos asociada o no a una debilidad de cinturas. No se han descrito hasta el momento casos de debilidad de cinturas aislada como sintoma de presentacion de esta mutacion. Caso clinico. Varon de 57 años, con clinica aislada de debilidad progresiva de cinturas, de cuatro años de evolucion. Hermano de una mujer de 59 años con la misma sintomatologia. La biopsia muscular fue decisiva en el diagnostico y es caracteristica de una miopatia mitocondrial. El analisis genetico objetivo la mutacion m.8344A>G del gen MTTK del ADN mitocondrial. Conclusiones. La mutacion 8344A>G del ADN mitocondrial puede cursar con un cuadro aislado de debilidad de cinturas de inicio en el adulto, por lo que debe de formar parte del diagnostico diferencial de este.

Promoter analysis and transcriptional regulation of human carbonic anhydrase VIII gene in a MERRF disease cell model.

Myoclonic epilepsy with ragged-red fibers (MERRF) is a maternally inherited mitochondrial neuromuscular disease. We previously reported a significant decrease of mRNA and protein levels of nuclear DNA-encoded carbonic anhydrase VIII (CA8) in MERRF cybrids harboring A8344G mutation in mitochondrial DNA (mtDNA). In this study, we established a reporter construct of luciferase gene-carrying hCA8 promoter containing several putative transcription factor-binding sites, including GC-box, AP-2 and TATA-binding element in the 5'flanking region of the hCA8 gene. Using a series of mutated hCA8 promoter constructs, we demonstrated that a proximal GC-box, recognized by Sp1 and other Sp family members, may be a key cis-element functioning at the promoter. Additionally, a significant increase of the hCA8 promoter activity was observed in the wild-type and mutant cybrids with over-expression of eGFP-Sp1, but no detectable increase in the CA8 protein expression. In contrast, over-expression of Flag-Sp1 and Flag-Sp4 significantly increased the hCA8 promoter activity as well as endogenous CA8 protein expression in neuron-like HEK-293 T cells. However, down-regulation of Sp1, but not Sp4, in 293 T cells revealed a significant reduction of CA8 expression, suggesting that Sp1 is a predominant transcription factor for regulation of CA8 activity. Furthermore, our data indicate that chromatin structure may be involved in the expression of hCA8 gene in MERRF cybrids. Taken together, these results suggest that Sp1 transactivates hCA8 gene through the proximal GC box element in the promoter region. The key modulator-responsive factor to the mtDNA mutation and how it may affect nuclear hCA8 gene transcription need further investigations.

Pathology of skeletal muscle fibers and small blood vessels in MERRF syndrome: an ultrastructural study.

Our studies concerned skeletal muscle biopsy specimens from a patient with clinically suspected MERRF syndrome, confirmed by genetic tests showing the presence of point mutation in the m.8344A> G in the tRNALys gene. Ultrastructurally, extensive damage of mitochondria in skeletal muscle fibres was observed, including the presence of two types of mitochondrial inclusions. Mild damage of mitochondria was revealed in small blood vessels and the presence of calcium deposits in the vascular walls were observed. The differences in mitochondrial damage may be related to different origin and expenditure of biologically useful energy in these cells.

Mitochondrial Transfer from Wharton's Jelly Mesenchymal Stem Cell to MERRF Cybrid Reduces Oxidative Stress and Improves Mitochondrial Bioenergetics.

Myoclonus epilepsy associated with ragged-red fibers (MERRF) is a maternally inherited mitochondrial disease affecting neuromuscular functions. Mt.8344A>G mutation in mitochondrial DNA (mtDNA) is the most common cause of MERRF syndrome and has been linked to an increase in reactive oxygen species (ROS) level and oxidative stress, as well as impaired mitochondrial bioenergetics. Here, we tested whether WJMSC has therapeutic potential for the treatment of MERRF syndrome through the transfer of mitochondria. The MERRF cybrid cells exhibited a high mt.8344A>G mutation ratio, enhanced ROS level and oxidative damage, impaired mitochondrial bioenergetics, defected mitochondria-dependent viability, exhibited an imbalance of mitochondrial dynamics, and are susceptible to apoptotic stress. Coculture experiments revealed that mitochondria were intercellularly conducted from the WJMSC to the MERRF cybrid. Furthermore, WJMSC transferred mitochondria exclusively to cells with defective mitochondria but not to cells with normal mitochondria. MERRF cybrid following WJMSC coculture (MF+WJ) demonstrated improvement of mt.8344A>G mutation ratio, ROS level, oxidative damage, mitochondrial bioenergetics, mitochondria-dependent viability, balance of mitochondrial dynamics, and resistance against apoptotic stress. WJMSC-derived mitochondrial transfer and its therapeutic effect were noted to be blocked by F-actin depolymerizing agent cytochalasin B. Collectively, the WJMSC ability to rescue cells with defective mitochondrial function through donating healthy mitochondria may lead to new insights into the development of more efficient strategies to treat diseases related to mitochondrial dysfunction.