Anticonvulsants ; therapeutic use ; Clonazepam ; therapeutic use ; Female ; Humans ; Levetiracetam ; therapeutic use ; MERRF Syndrome ; drug therapy ; Male ; Myoclonus ; drug therapy

Adult ; DNA, Mitochondrial ; genetics ; Electroencephalography ; Humans ; MERRF Syndrome ; genetics ; Male ; Mitochondrial Myopathies ; genetics ; Mutation ; RNA, Transfer, Asn ; genetics

PURPOSE: Mitochondrial diseases are clinically and genetically heterogeneous disorders, which make their exact diagnosis and classification difficult. The purpose of this study was to identify pathogenic mitochondrial DNA (mtDNA) mutations in 2 Korean families with myoclonic epilepsy with ragged-red fibers (MERRF) and Leigh syndrome, respectively. MATERIALS AND METHODS: Whole mtDNAs were sequenced by the method of mtDNA-targeted next-generation sequencing (NGS). RESULTS: Two causative mtDNA mutations were identified from the NGS data. An m.8344A>G mutation in the tRNA-Lys gene (MT-TK ) was detected in a MERRF patient (family ID: MT132), and an m.9176T>C (p.Leu217Pro) mutation in the mitochondrial ATP6 gene (MT-ATP6) was detected in a Leigh syndrome patient (family ID: MT130). Both mutations, which have been reported several times before in affected individuals, were not found in the control samples. CONCLUSION: This study suggests that mtDNA-targeted NGS will be helpful for the molecular diagnosis of genetically heterogeneous mitochondrial diseases with complex phenotypes.
Classification ; Diagnosis ; DNA, Mitochondrial ; Humans ; Leigh Disease* ; MERRF Syndrome* ; Mitochondrial Diseases ; Phenotype

Quality control for genetic tests has become more important as the test volume and clinical demands increase dramatically. The diagnostic genetics subcommittee of the Korean Association of Quality Assurance for Clinical Laboratories performed two trials for cytogenetics and molecular genetics surveys in 2013. A total of 43 laboratories participated in the cytogenetic surveys, 30 laboratories participated in the fluorescent in situ hybridization surveys, and 122 laboratories participated in the molecular genetics surveys in 2013. Almost all of them showed acceptable results. However, some laboratories had unacceptable results for karyotype nomenclature, detection of complex cytogenetic abnormalities in hematologic neoplasms and constitutional anomalies. The molecular genetics surveys included various tests: Mycobacterium tuberculosis detection, hepatitis B and C virus detection and quantification, human papilloma virus genotyping, gene rearrangement tests for leukaemia and lymphomas, genetic tests for JAK2, fms-related tyrosine kinase 3, Nucleophosmin, cancer-associated genes (KRAS, EGFR and BRAF), hereditary breast and ovarian cancer genes (BRCA1 and BRCA2), Li-Fraumeni syndrome (TP53), Wilson disease (ATP7B), achondroplasia (FGFR3), Huntington disease, spinocerebellar ataxia, spinal and bulbar muscular atrophy, mitochondrial encephalopathy with lactic acidosis and stroke like episodes, myoclonic epilepsy associated with ragged-red fibers, Prader-Willi/Angelman syndrome, Duchenne muscular dystrophy, spinal muscular atrophy, Fragile X syndrome, non-syndromic hearing loss and deafness (GJB2), apolipoprotein E genotyping, methylenetetrahydrofolate reductase genotyping, ABO genotyping and DNA sequence analysis. Molecular genetic surveys showed excellent results for most of the participants. The external quality assessment program for genetic analysis in 2013 was proved to be helpful for continuous education and evaluation of quality improvement.
Achondroplasia ; Acidosis, Lactic ; Apolipoproteins ; Breast ; Chromosome Aberrations ; Cytogenetics ; Deafness ; Education ; Fragile X Syndrome ; Gene Rearrangement ; Genetics* ; Hearing Loss ; Hematologic Neoplasms ; Hepatitis B ; Hepatolenticular Degeneration ; Humans ; Huntington Disease ; In Situ Hybridization, Fluorescence ; Karyotype ; Korea ; Li-Fraumeni Syndrome ; Lymphoma ; MERRF Syndrome ; Methylenetetrahydrofolate Reductase (NADPH2) ; Molecular Biology ; Muscular Atrophy, Spinal ; Muscular Disorders, Atrophic ; Muscular Dystrophy, Duchenne ; Mycobacterium tuberculosis ; Ovarian Neoplasms ; Papilloma ; Protein-Tyrosine Kinases ; Quality Control ; Quality Improvement ; Sequence Analysis, DNA ; Spinocerebellar Ataxias ; Stroke

Mitochondrion is an intracellular organelle with its own genome. Its function in cellular metabolism is indispensable that mitochondrial dysfunction gives rise to multisystemic failure. The manifestation is most prominent with tissues of high energy demand such as muscle and nerve. Mitochondrial myopathies occur not only by mutations in mitochondrial genome, but also by defects in nuclear genes or secondarily by toxic insult on mitochondrial replication. Currently curative treatment modality does not exist and symptomatic treatment remains mainstay. Administration of L-arginine holds great promise according to the recent reports. Advances in mitochondrial RNA import might enable a new therapeutic strategy.
Arginine ; Genome ; Genome, Mitochondrial ; MELAS Syndrome ; MERRF Syndrome ; Mitochondria ; Mitochondrial Myopathies ; Muscles ; Ophthalmoplegia, Chronic Progressive External ; Organelles ; RNA

This study was conducted to investigate the etiology, the clinical characteristics and prognosis of acute necrotizing encephalopathy (ANE) in Korean children. Six children (1 yr to 7 yr) patients with ANE were enrolled. They were diagnosed by clinical and radiological characteristics and their clinical data were retrospectively analyzed. In a search of clinically plausible causes, brain MRI in all patients, mitochondrial DNA studies for mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes (MELAS) and myoclonus epilepsy and ragged red fibers (MERRF) in four patients, and genomic typing on HLA DRB/HLA DQB genes in three patients were performed. All had precedent illnesses and the main initial symptoms included mental change (83%), seizures (50%), and focal deficits (50%). MRI revealed increased T2 signal density in the bilateral thalami and/or the brainstem in all patients. Mitochodrial DNA studies for MELAS and MERRF were negative in those children and HLA-DRB1*1401, HLA-DRB3*0202, and HLA-DQB1*0502 seemed to be significant. A high dose steroid was given to all patients, which seemed to be partly effective except for 2 patients. In conclusion, ANE is relatively rare, but can result in serious neurological complication in children. Early detection and appropriate treatment may lead to a better neurological outcome.
Child ; Child, Preschool ; Female ; HLA-DQ Antigens/metabolism ; HLA-DQ beta-Chains ; HLA-DR Antigens/metabolism ; HLA-DRB1 Chains ; HLA-DRB3 Chains ; Humans ; Infant ; Korea ; Leukoencephalitis, Acute Hemorrhagic/diagnosis/etiology/*pathology/*physiopathology ; MELAS Syndrome/pathology/physiopathology ; MERRF Syndrome/pathology/physiopathology ; Magnetic Resonance Imaging ; Male ; Prognosis ; Retrospective Studies

Mitochondrial diseases are clinically and genetically heterogeneous disorders, which make the exact diagnosis and classification difficult. The purpose of this study was to identify pathogenic mtDNA mutations in 61 Korean unrelated families (or isolated patients) with MELAS or MERRF. In particular, the mtDNA sequences were completely determined for 49 patients. From the mutational analysis of mtDNA obtained from blood, 5 confirmed pathogenic mutations were identified in 17 families, and 4 unreported pathogenically suspected mutations were identified in 4 families. The m.3243A>G in the tRNA(Leu(UUR)) was predominantly observed in 10 MELAS families, and followed by m.8344A>G in the tRNA(Lys) of 4 MERRF families. Most pathogenic mutations showed heteroplasmy, and the rates were considerably different within the familial members. Patients with a higher rate of mutations showed a tendency of having more severe clinical phenotypes, but not in all cases. This study will be helpful for the molecular diagnosis of mitochondrial diseases, as well as establishment of mtDNA database in Koreans.
Adolescent ; Adult ; Amino Acid Sequence ; Asian Continental Ancestry Group/genetics ; Base Sequence ; DNA Mutational Analysis ; DNA, Mitochondrial/analysis/*genetics ; Female ; Humans ; MELAS Syndrome/diagnosis/*genetics ; MERRF Syndrome/diagnosis/*genetics ; Male ; Middle Aged ; Molecular Diagnostic Techniques ; Pedigree ; Polymorphism, Single Nucleotide ; Sequence Homology ; Young Adult

Multiple symmetric lipomatosis is a rare disorder characterized by massive fatty deposits arranged symmetrically around the neck, shoulder, abdomen and back. It is typically associated with high alcohol consumption and a high prevalence of peripheral neuropathy. The pathogenesis of the syndrome is still unknown, but mitochondrial abnormality or metabolic abnormalities are occasionally found in the affected patients. In our patient, clinical and electrophysiologic signs of a generalized peripheral sensorimotor neuropathy and a multiple bilateral lumbosacral radiculopathy were observed. Sural nerve biopsy demonstrated many small unmyelinated fibers with complete loss of axoplasm and a extensive loss of myelinated fibers. Lipoma biopsy demonstrated non-capsulated mature adipose cells in the subcutaneous tissue. Serum lipid studies were normal. MERRF point mutation of mitochondrial DNA were negative in blood. We reported a case of multiple symmetric lipomatosis and peripheral polyneuropathy with the review of literature.
Abdomen ; Alcohol Drinking ; Biopsy ; DNA, Mitochondrial ; Humans ; Lipoma ; Lipomatosis, Multiple Symmetrical* ; MERRF Syndrome ; Myelin Sheath ; Neck ; Peripheral Nervous System Diseases* ; Point Mutation ; Polyneuropathies ; Prevalence ; Radiculopathy ; Shoulder ; Subcutaneous Tissue ; Sural Nerve

We describe a unique patient with progressive external ophthalmoplegia, intestinal pseudo-obstruction, and neurogenic bladder. Genetic study in this patient shows point mutation at T8356C, the locus known as that of myoclonic epilepsy with ragged-red fibers. To the best of our knowledge, this is the first report of a mitochondrial syndrome consisting of intestinal pseudo-obstruction, neurogenic bladder, and progressive external ophthalmoplegia, point mutation at T8356C. We suggest that this could comprise a new mitochondrial disease rather than a new variant of mitochondrial neurogastrointestinal encephalomyopathy.
Humans ; Intestinal Pseudo-Obstruction* ; MERRF Syndrome ; Mitochondrial Diseases* ; Ophthalmoplegia, Chronic Progressive External ; Point Mutation* ; Urinary Bladder, Neurogenic*

Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episode (MELAS) and myoclonic epilepsy and raggedred fibers (MERRF) are rare disorders caused by point mutation of the tRNA gene of the mitochondrial genome. To understand the pathogenetic mechanism of MELAS and MERRF, we studied four patients. Serially sectioned frozen muscle specimens with a battery of histochemical stains were reviewed under light microscope and ultrastructural changes were observed under electron microscope. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was performed and the tRNA genes were sequenced to confirm mutations. In two patients with MELAS, strongly succinyl dehydrogenase positive blood vessels (SSVs) and many cytochrome oxidase (COX) positive raggedred fibers (RRFs) were observed, and A3243G mutations were found from the muscle samples. In two patients with MERRF, neither SSV nor COX positive RRFs were seen and A8344G mutations were found from both muscle and blood samples. In the two MERRF families, the identical mutation was observed among family members. The failure to detect the mutation in blood samples of the MELAS suggests a low mutant load in blood cells. The histochemical methods including COX stain are useful for the confirmation and differentiation of mitochondrial diseases. Also, molecular biological study using muscle sample seems essential for the confirmation of the mtDNA mutation.
Adolescent ; Adult ; Electron Transport Complex IV/metabolism ; Female ; Humans ; Korea ; MELAS Syndrome/*genetics/metabolism/*pathology ; MERRF Syndrome/*genetics/metabolism/*pathology ; Male ; Pedigree ; Polymerase Chain Reaction/methods ; Polymorphism, Restriction Fragment Length ; RNA, Transfer ; Sequence Analysis, DNA