-
Child Neurology Open 2021In the field of mitochondrial medicine, correlation of clinical phenotype with mutation heteroplasmy remains an outstanding question with few, if any, clear thresholds...
In the field of mitochondrial medicine, correlation of clinical phenotype with mutation heteroplasmy remains an outstanding question with few, if any, clear thresholds corresponding to a given phenotype. The m.8344A>G mutation is most commonly associated with myoclonus epilepsy and ragged red fiber syndrome (MERRF) at varying levels of heteroplasmy. However, a handful of cases been previously reported in which individuals homoplasmic or nearly homoplasmic for this mutation in the blood have presented with multiple bulbar palsies, respiratory failure, and progressive neurologic decline almost uniformly following a respiratory illness. MRI brain in all affected individuals revealed symmetric T2 hyperintense lesions of subcortical gray matter structures, consistent with Leigh syndrome. Here, we present 3 cases with clinical, biochemical, and neuro-imaging findings with the additional reporting of spinal lesions. This new phenotype supports a heteroplasmy-dependent phenotype model for this mutation and recognition of this can help clinicians with diagnosis and anticipatory clinical guidance.
PubMed: 33718511
DOI: 10.1177/2329048X21991382 -
A&A Practice Feb 2021Myoclonic epilepsy with ragged red fibers (MERRF) syndrome is a rare mitochondrial disease potentially associated with increased sensitivity to anesthesia and metabolic...
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.
Topics: Adult; Anesthesia, General; Humans; MERRF Syndrome; Male; Malignant Hyperthermia; Middle Aged; Mitochondrial Diseases; Sevoflurane
PubMed: 33577170
DOI: 10.1213/XAA.0000000000001401 -
Frontiers in Genetics 2020Mitochondrial diseases are a heterogeneous group of rare genetic disorders that can be caused by mutations in nuclear (nDNA) or mitochondrial DNA (mtDNA). Mutations in... (Review)
Review
Mitochondrial diseases are a heterogeneous group of rare genetic disorders that can be caused by mutations in nuclear (nDNA) or mitochondrial DNA (mtDNA). Mutations in mtDNA are associated with several maternally inherited genetic diseases, with mitochondrial dysfunction as a main pathological feature. These diseases, although frequently multisystemic, mainly affect organs that require large amounts of energy such as the brain and the skeletal muscle. In contrast to the difficulty of obtaining neuronal and muscle cell models, the development of induced pluripotent stem cells (iPSCs) has shed light on the study of mitochondrial diseases. However, it is still a challenge to obtain an appropriate cellular model in order to find new therapeutic options for people suffering from these diseases. In this review, we deepen the knowledge in the current models for the most studied mt-tRNA mutation-caused mitochondrial diseases, MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) and MERRF (myoclonic epilepsy with ragged red fibers) syndromes, and their therapeutic management. In particular, we will discuss the development of a novel model for mitochondrial disease research that consists of induced neurons (iNs) generated by direct reprogramming of fibroblasts derived from patients suffering from MERRF syndrome. We hypothesize that iNs will be helpful for mitochondrial disease modeling, since they could mimic patient's neuron pathophysiology and give us the opportunity to correct the alterations in one of the most affected cellular types in these disorders.
PubMed: 33510772
DOI: 10.3389/fgene.2020.610764 -
Annals of Neurology Mar 2021
Topics: Aged; Ataxia; DNA, Mitochondrial; Genetic Testing; Humans; Lipomatosis; MERRF Syndrome; Magnetic Resonance Imaging; Male; Myoclonus; Neck
PubMed: 33341990
DOI: 10.1002/ana.25992 -
Polish Journal of Pathology : Official... 2020The 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%...
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.
Topics: DNA, Mitochondrial; Humans; MERRF Syndrome; Mutation; Pedigree
PubMed: 33112121
DOI: 10.5114/pjp.2020.99797 -
Case Reports in Neurological Medicine 2020Although endocrinologic involvement and epilepsy are frequent features of myoclonic epilepsy with ragged-red fibers (MERRF), polycystic ovary syndrome (PCOS) and...
OBJECTIVES
Although endocrinologic involvement and epilepsy are frequent features of myoclonic epilepsy with ragged-red fibers (MERRF), polycystic ovary syndrome (PCOS) and photosensitive epilepsy have not been reported. . A 32-year-old female was diagnosed with MERRF at age 19 y upon presence of the four canonical features and the variant m.8344A > G in () (blood heteroplasmy rate: 50%). She experienced recurrent photosensitive focal and generalised seizures since age 19 y, which could be triggered by flickering light or by looking at small stones, leaves, or dirty snow on the ground. Since the last 42 months, she was seizure-free upon levetiracetam (4000 mg/d), clonazepam (1.5 mg/d), and topiramate (25 mg/d). Additionally, she suffered from secondary amenorrhoea since adolescence. She was married between ages 19 y and 25 y but did not get pregnant. PCOS was diagnosed and treated with desogestrel plus estradiol. Nonetheless, the course was progressive, particularly with regard to ataxia, myocloni, and myopathy.
CONCLUSIONS
The phenotypic spectrum of MERRF is broader than anticipated and may additionally include PCOS and photosensitive epilepsy. PCOS in MERRF may respond to hormone substitution and photosensitive epilepsy to levetiracetam, clonazepam, and topiramate.
PubMed: 33062354
DOI: 10.1155/2020/8876272 -
Beijing Da Xue Xue Bao. Yi Xue Ban =... Oct 2020Mitochondrial deoxyribonucleic acid (mtDNA) 8344 A>G (m.8344A>G) mutation is the common mutation associated with mitochondrial myoclonus epilepsy with ragged-red fibers...
[Mitochondrial encephalopathy, lactic acidosis and stroke-like episodes / myoclonus epilepsy with ragged-red fibers /Leigh overlap syndrome caused by mitochondrial DNA 8344A>G mutation].
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 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.
Topics: Acidosis, Lactic; Adult; Child; DNA, Mitochondrial; Humans; Male; Mitochondrial Encephalomyopathies; Mutation; Stroke; Young Adult
PubMed: 33047718
DOI: 10.19723/j.issn.1671-167X.2020.05.009 -
Cerebellum & Ataxias 2020Despite the broad development of next-generation sequencing approaches recently, such as whole-exome sequencing, diagnostic workup of adult-onset progressive cerebellar...
BACKGROUND
Despite the broad development of next-generation sequencing approaches recently, such as whole-exome sequencing, diagnostic workup of adult-onset progressive cerebellar ataxias without remarkable family history and with negative genetic panel testing for SCAs remains a complex and expensive clinical challenge.
CASE PRESENTATION
In this article, we report a Brazilian man with adult-onset slowly progressive pure cerebellar ataxia, which developed neuropathy and hearing loss after fifteen years of ataxia onset, in which a primary mitochondrial DNA defect (MERRF syndrome - myoclonus epilepsy with ragged-red fibers) was confirmed through muscle biopsy evaluation and whole-exome sequencing.
CONCLUSIONS
Mitochondrial disorders are a clinically and genetically complex and heterogenous group of metabolic diseases, resulting from pathogenic variants in the mitochondrial DNA or nuclear DNA. In our case, a correlation with histopathological changes identified on muscle biopsy helped to clarify the definitive diagnosis. Moreover, in neurodegenerative and neurogenetic disorders, some symptoms may be evinced later during disease course. We suggest that late-onset and adult pure undetermined ataxias should be considered and investigated for mitochondrial disorders, particularly MERRF syndrome and other primary mitochondrial DNA defects, together with other more commonly known nuclear genes.
PubMed: 32922825
DOI: 10.1186/s40673-020-00122-0 -
Pathology International Nov 2020
Topics: Adult; Aged; Autopsy; Fatal Outcome; Female; Genes, Mitochondrial; Humans; Immunohistochemistry; Islets of Langerhans; MELAS Syndrome; MERRF Syndrome; Male; Middle Aged; Point Mutation
PubMed: 32808720
DOI: 10.1111/pin.13008