Heteroplasmic pathogenic m.12315G>A variant in MT-TL2 presenting with MELAS syndrome and depletion of nitric oxide donors.

The MT-TL2 m.12315G>A pathogenic variant has previously been reported in five individuals with mild clinical phenotypes. Herein we report the case of a 5-year-old child with heteroplasmy for this variant who developed neurological regression and stroke-like episodes similar to those observed in mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). Biochemical evaluation revealed depletion of arginine on plasma amino acid analysis and low z-scores for citrulline on untargeted plasma metabolomics analysis. These findings suggested that decreased availability of nitric oxide may have contributed to the stroke-like episodes. The use of intravenous arginine during stroke-like episodes and daily enteral L-citrulline supplementation normalized her biochemical values of arginine and citrulline. Untargeted plasma metabolomics showed the absence of nicotinamide and 1-methylnicotinamide, and plasma total glutathione levels were low; thus, nicotinamide riboside and N-acetylcysteine therapies were initiated. This report expands the phenotype associated with the rare mitochondrial variant MT-TL2 m.12315G>A to include neurological regression and a MELAS-like phenotype. Individuals with this variant should undergo in-depth biochemical analysis to include untargeted plasma metabolomics, plasma amino acids, and glutathione levels to help guide a targeted approach to treatment.

Thalamic aphasia associated with mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes: A case report.

BACKGROUND: Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) with aphasia is a rare disorder, with the associated aphasia reported as either Wernicke's or Broca's. Herein, we report a patient with MELAS complicated by thalamic aphasia. CASE: A 15-year-old right-handed girl presented with headache, nausea, right homonymous hemianopsia, and aphasia. She could repeat words said by others, but had word-finding difficulty, paraphasia, and dysgraphia. Brain MRI revealed abnormal signals from the left occipital lobe to the temporal lobe and left thalamus, but Wernicke's area and Broca's area were not involved. Additionally, she had short stature, lactic acidosis, bilateral sensorineural hearing loss, and a maternal family history of diabetes and mild deafness. Based on clinical findings and the presence of a mitochondrial A3243G mutation, she was diagnosed with MELAS. With treatment, the brain MRI lesions disappeared and her symptoms improved. Her aphasia was classified as amnesic aphasia because she could repeat words, despite having word-finding difficulty, paraphasia, and dysgraphia. Based on MRI findings of a left thalamic lesion, we diagnosed her with thalamic aphasia. CONCLUSION: Thalamic aphasia may be caused by MELAS. Assessment of whether repetition is preserved is important for classifying aphasia.

Impaired nitric oxide production in children with MELAS syndrome and the effect of arginine and citrulline supplementation.

Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is one of the most frequent maternally inherited mitochondrial disorders. The pathogenesis of this syndrome is not fully understood and believed to result from several interacting mechanisms including impaired mitochondrial energy production, microvasculature angiopathy, and nitric oxide (NO) deficiency. NO deficiency in MELAS syndrome is likely to be multifactorial in origin with the decreased availability of the NO precursors, arginine and citrulline, playing a major role. In this study we used stable isotope infusion techniques to assess NO production in children with MELAS syndrome and healthy pediatric controls. We also assessed the effect of oral arginine and citrulline supplementations on NO production in children with MELAS syndrome. When compared to control subjects, children with MELAS syndrome were found to have lower NO production, arginine flux, plasma arginine, and citrulline flux. In children with MELAS syndrome, arginine supplementation resulted in increased NO production, arginine flux, and arginine concentration. Citrulline supplementation resulted in a greater increase of these parameters. Additionally, citrulline supplementation was associated with a robust increase in citrulline concentration and flux and de novo arginine synthesis rate. The greater effect of citrulline in increasing NO production is due to its greater ability to increase arginine availability particularly in the intracellular compartment in which NO synthesis takes place. This study, which is the first one to assess NO metabolism in children with mitochondrial diseases, adds more evidence to the notion that NO deficiency occurs in MELAS syndrome, suggests a better effect for citrulline because of its greater role as NO precursor, and indicates that impaired NO production occurs in children as well as adults with MELAS syndrome. Thus, the initiation of treatment with NO precursors may be beneficial earlier in life. Controlled clinical trials to assess the therapeutic effects of arginine and citrulline on clinical complications of MELAS syndrome are needed.

Mitochondrial disease and epilepsy.

Mitochondrial respiratory chain disorders are relatively common inborn errors of energy metabolism, with a combined prevalence of one in 5000. These disorders typically affect tissues with high energy requirements, and cerebral involvement occurs frequently in childhood, often manifesting in seizures. Mitochondrial diseases are genetically heterogeneous; to date, mutations have been reported in all 37 mitochondrially encoded genes and more than 80 nuclear genes. The major genetic causes of mitochondrial epilepsy are mitochondrial DNA mutations (including those typically associated with the mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes [MELAS] and myoclonic epilepsy with ragged red fibres [MERRF] syndromes); mutations in POLG (classically associated with Alpers syndrome but also presenting as the mitochondrial recessive ataxia syndrome [MIRAS], spinocerebellar ataxia with epilepsy [SCAE], and myoclonus, epilepsy, myopathy, sensory ataxia [MEMSA] syndromes in older individuals) and other disorders of mitochondrial DNA maintenance; complex I deficiency; disorders of coenzyme Q(10) biosynthesis; and disorders of mitochondrial translation such as RARS2 mutations. It is not clear why some genetic defects, but not others, are particularly associated with seizures. Epilepsy may be the presenting feature of mitochondrial disease but is often part of a multisystem clinical presentation. Mitochondrial epilepsy may be very difficult to manage, and is often a poor prognostic feature. At present there are no curative treatments for mitochondrial disease. Individuals with mitochondrial epilepsy are frequently prescribed multiple anticonvulsants, and the role of vitamins and other nutritional supplements and the ketogenic diet remain unproven.

Endothelial dysfunction in MELAS improved by l-arginine supplementation.

The authors evaluated endothelial function in patients with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke) by flow-mediated vasodilation (FMD) and found a significant decrease vs controls. Two years of supplementation with oral l-arginine, a nitric oxide precursor, significantly improved endothelial function to control levels and was harmonized with the normalized plasma levels of l-arginine in patients. l-Arginine therapy improved endothelial dysfunction and showed promise in treating strokelike episodes in MELAS.

[Characteristics of status epilepticus in MELAS. Analysis of four cases]. / Características del estado del mal epiléptico en MELAS. Análisis de cuatro casos.

INTRODUCTION: Clinical characteristics of status epilepticus (SE) as a first manifestation in patients with MELAS who had not previously epileptic episode has been studied little in the literature. OBJECTIVES: Our aim was to analyse precipitating factors, clinical characteristics, EEG and difficulties in the treatment of SE in MELAS. PATIENTS AND METHODS: We studied four cases with ages between 27 an 41 years who began with SE and they had been diagnosed with MELAS during the episode. Case 3 was confirmed by autopsy. Cases 1, 2 and 4 showed a 3243 mtDNA mutation in the lymphocytes. Epileptic seizures had not been present in any previous status case. The precipitating factor in cases 1 and 3 was fever and in case 2 and 4 stress by headache. Moreover in case 2 second status was caused by stress in hyperglycaemic ketoacidosis. All cases were studied with EEG and a brain CT or MRI. RESULTS: All patients started with epilepsia partialis continua that began with partial motor simple seizures, but sometimes progressed to partial complex seizures or secondary tonic clonic seizures. In two cases the initial symptom was migraine with aura, in two cases fever with cephalalgia and in one case diabetes mellitus decompensation. The EEG during a seizure presented a complex pseudoperiodic complex in the temporal-occipital contralateral region that spread to all hemisphere when myoclonus was increased. CONCLUSIONS: SE in MELAS appears in cell stress situation precipitated by hypermetabolic conditions and it provokes claudication in ill mitochondria. In fact, events such as fever, glycemic alterations, hypoxemia or headache that could change the normal mechanism of sequester mitochondrial calcium in the neuron are able to trigger SE. Optimal evolution depends on an improvement of basal metabolic conditions that could precipitate the status. Supplementary folic acid, riboflavin and coenzyme Q 10 can be useful.

Características del estado del mal epiléptico en MELAS. Análisis de cuatro casos / Characteristics of status epilepticus in MELAS. Analysis of four cases

Introducción. El estado de mal epiléptico (EE) como primera manifestación en pacientes con MELAS que previamente no habían tenido crisis epilépticas ha sido escasamente analizado en la literatura.Objetivos. Nuestro propósito ha sido analizar los factores precipitantes, las características electroclínicas y las dificultades en el tratamiento del EE en el MELAS.Pacientes y métodos. Analizamos cuatro casos diagnosticados de MELAS, con edades comprendidas entre 27 y 41 años, que se inician con un EE y son diagnosticados de MELAS durante el episodio. El diagnóstico se realizó en los casos 1, 2 Y 4 analizando en una muestra de sangre periférica el ADN mitocondrial, obteniéndose en todos ellos la mutación 3243 en el ADN linfocitario. El caso 3 se confirmó por necropsia. Ninguno de los pacientes había presentado crisis epilépticas previamente. El factor desencadenante en los casos 1 y 3 fue la fiebre, mientras que los casos 2 y 4 se asociaron a migraña con aura. El estrés provocado por la hiperglucemia cetoacidótica desencadenó el segundo episodio en el caso 2. Todos los casos fueron estudiados con EEG, TC o RM craneal.Resultados. Clínica mente todos los pacientes empezaron con una epilepsia parcial continua que comenzó con crisis parciales motoras simples, pudiendo progresar a crisis parciales complejas o a crisis tonicoclónicas secundariamente generalizadas. En dos ocasiones se asoció a migraña con aura, en dos casos a fiebre con cefalea y en uno a descompensación diabética. El EEG durante las crisis mostraba complejos seudoperiódicos en la región temporo-occipital que se difundían a todo el hemisferio o contra lateralmente cuando se incrementaban las mioclonías.Conclusiones. El EE en el MELAS aparece en situaciones de estrés celular, desencadenado por situaciones hipermetabólicas que hacen claudicar a las mitocondrias enfermas. De esta manera efectos como fiebre, alteraciones de la glucemia o crisis migrañosas que puedan modificar el mecanismo habitual de secuestro del calcio mitocondrial en la neurona son capaces de desencadenarlo. El pronóstico dependerá en parte de la mejoría de las condiciones metabólicas basa les que lo han precipitado

Introduction. Clinical characteristics of status epilepticus (SE) as a first manifestation in patients with MELAS who had not previously epileptic episode has been studied little in the literature.Objectives. Our aim was to analyse precipitating factors, clinical characteristics, EEG and difficulties in the treatment of SE in MELAS.Patients and methods. We studied four cases with ages between 27 an 41 years who began with SE and they had been diagnosed with MELAS during the episode. Case 3 was confirmed by autopsy. Cases 1, 2 and 4 showed a 3243 mtDNA mutation in the lymphocytes. Epileptic seizures had not been present in any previous status case. The precipitating factor in cases 1 and 3 was fever and in case 2 and 4 stress by headache. Moreover in case 2 second status was caused by stress in hyperglycaemic ketoacidosis. AlI cases were studied with EEG and a brain CT or MRI.Results. All patients started with epilepsia partialis continua that began with partial motor simple seizures, but sometimes progressed to partial complex seizures or secondary tonic clonic seizures. In two cases the initial symptom was migraine with aura, in two cases fever with cephalalgia and in one case diabetes mellitus decompensation. The EEG during a seizure presented a complex pseudoperiodic complex in the temporal-occipital contralateral region that spread to all hemisphere when myoclonus was increased.Conclusions. SE in MELAS appears in cell stress situation precipitated by hypermetabolic conditions and it provokes claudication in ill mitochondria. In fact, events such as fever, glycemic alterations, hypoxemia or headache that could change the normal mechanism of sequester mitochondrial calcium in the neuron are able to trigger SE. Optimal evolution depends on an improvement of basal metabolic conditions that could precipitate the status. Supplementary folic acid, riboflavin and coenzyme Q 10 can be useful

Auditory symptoms: a critical clue for diagnosis of MELAS.

Mitochondrial encephalopathy, lactic acidosis with stroke-like episodes (MELAS) is a rare mitochondrial disorder that affects adults. MELAS syndrome can mimic cerebrovascular disease, encephalitis or toxic-metabolic encephalopathy. The authors reported two patients who presented with auditory symptoms before the onset of encephalopathy and stroke-like episodes. The first patient was a 28 year-old man, who presented with acute sensorineural hearing loss (SNHL) followed by headache, left hemiparesis and generalized tonic-clonic seizure. CT scan of the brain showed hypodensity lesion at the tip of right temporooccipital region. Audiogram and brainstem auditory evoked potential (BAEP) showed abnormal conduction of left brainstem auditory pathway. MRI of the brain showed a lesion involving gray and white matters of the right occipital, parietal and temporal lobes. The distribution of the lesions was not compatible with distribution of arterial supply. MRA was normal. The second patient was a 56 year-old woman with a one-year history of hearing loss. The audiogram revealed bilateral SNHL. A few days before admission, her hearing was acutely deteriorated She could not understand a conversation while she could communicate by writing. CT scan of the brain showed hypodensity in both temporal lobes and MRI revealed lesions in the same area. Pure tone audiogram showed moderate SNHL but BAEP was normal. One week later, she developed global dysphasia and generalized tonic-clonic seizure. Both patients had elevated cerebrospinal fluid and serum lactate: pyruvate ratio. Polymerase chain reaction-restriction fragment length polymorphism disclosed A3243G mtDNA mutation in the blood in the first patient and in muscle biopsy in the second patient. Ubiquinone supplement was prescribed The auditory symptoms in combination with stroke-like episode in supratentorium are important clues to diagnose MELAS syndrome.

Effect of coenzyme Q10 in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS): evaluation by noninvasive tissue oximetry.

We evaluated the effect of coenzyme Q10 supplementation to two patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) by using noninvasive tissue oximetry with near-infrared spectra of hemoglobin from the quadriceps muscle during bicycle ergometer exercise. Patients showed distinct oxygen consumption patterns reflecting the defect in oxidative phosphorylation and the impairment in oxygen utilization during exercise. Based on the oxygen consumption pattern, we considered one patient as having severe mitochondrial disorder and another patient as having mild one. After coenzyme Q10 supplementation, the oxygen consumption pattern of the patient with the severe form shifted to the mild one, while that of the patient with mild form remained unchanged. The shift of the pattern to the mild form correlated well with reduction of the sum of the serum lactate and pyruvate content during exercise. Noninvasive tissue oximetry may be useful to evaluate the effect of coenzyme Q10 supplementation to patients with mitochondrial encephalomyopathy including MELAS.

Lesions affecting the claustrum.

MR imaging examinations of seven patients with a variety of claustral disorders are included in this study. The ages of the patients ranged from 4 to 65 years, and all of them were males. The lesions involving the claustrum comprised cases with asphyxia, Wilson's disease, ischemic white matter disease, thalamic arteriovenous malformation, MELAS syndrome, viral encephalitis and Parkinson's disease.

CPEO and carnitine deficiency overlapping in MELAS syndrome.

Mitochondrial myopathy, encephalopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome is one of the mitochondrial encephalomyopathies that has distinct clinical features including stroke-like episodes with migraine-like headache, nausea, vomiting, encephalopathy and lactic acidosis. We report a 27-year-old woman who presented with partial seizure, stroke-like episodes including hemiparesis, hemianopia and hemihypethesia, sensorineural hearing loss, migraine-like headache, and lactic acidosis. Brain computed tomographic scan showed encephalomalacia in the right parieto-occipital area and recent hypodensity in the left temporoparieto-occipital area with cortical atrophy. Muscle biopsy revealed ragged-red fibers and paracrystaline inclusions in the mitochondria. Genetic study revealed an A to G point mutation at nucleotide position (np) 3243 of mitochondrial DNA. External ophthalmoplegia and ptosis were also found during two exaggerated episodes in this patient. Therefore, the overlapping syndrome of chronic progressive external ophthalmoplegia in the MELAS syndrome is considered in this case. Furthermore, we also found carnitine deficiency in this patient and she was responsive well to steroid therapy. Muscle biopsy also revealed excessive lipid droplets deposits. Therefore, the carnitine deficiency may occur in MELAS syndrome with the A to G point mutation at np 3243. We recommend the steroid or carnitine supplement therapy be applied to the MELAS syndrome with carnitine deficiency.

Stroke, hemiparesis and deficient mitochondrial beta-oxidation.

We describe on a 3-year-old child referred for evaluation and therapy of a cerebral vascular accident with residual hemiplegia and partial epilepsy. Metabolic investigations initially showed normal urinary organic acids as well as normal blood and urinary amino acids. Blood carnitine fractions had been pathological and a secondary carnitine deficiency was diagnosed and treated by oral L-carnitine supplementation. During carnitine treatment, abnormal urinary acylcarnitine profiles were noticed with excessive amounts of several carnitine esters including propionylcarnitine, butyryl- and/or isobutyryl-carnitine, isovaleryl- and/or 2-methylbutyryl-carnitine, hexanoylcarnitine and octanoylcarnitine. Subsequently, an urinary organic acid profile suggestive of glutaric aciduria type II was recorded during a clinical decompensation crisis. Morphological and biochemical studies on skeletal muscle and skin fibroblasts were performed and confirmed the existence of a defect of the mitochondrial beta-oxidation pathways with lipidic myopathy, reduced palmitate and octanoate oxidation rates in cultured fibroblasts. Glutaric aciduria type II increases the list of metabolic disorders characterized by hemiplegia and other sequelae of brain ischaemia such as stroke-like episode, seizures, aphasia, ataxia and myoclonia, similar to those seen in MELAS.