OBJECTIVE: To explore the genetic basis for a child with myopathy and cerebellar atrophy with ataxia. METHODS: Clinical examinations and laboratory testing were carried out for the patient. The proband and the parents' genomic DNA was extracted from peripheral blood samples and subjected to trio whole-exome sequencing. Candidate variant was validated by Sanger sequencing. RESULTS: The 1-year-and-8-month-old boy manifested motor developmental delay, ataxia, hypomyotonia, increased serum creatine kinase. Cranial MRI showed cerebellar atrophy with progressive aggravation. Genetic testing revealed that the patient has harbored compound heterozygous variants of the MSTO1 gene, namely c.13delG (p.Ala5ProfsTer68) and c.971C>T (p.Thr324Ile), which were respectively inherited from his mother and father. The former was unreported previously and was predicted to be likely pathogenic, whilst the latter has been reported previously and was predicted to be of uncertain significance. CONCLUSION The compound heterozygous c.13delG (p.Ala5ProfsTer68) and c.971C>T (p.Thr324Ile) variants probably underlay the disease in the proband. Above finding has enriched the spectrum of MSTO1 gene variants underlying mitochondrial myopathy and cerebellar atrophy with ataxia.
Ataxia/genetics* ; Atrophy/genetics* ; Cell Cycle Proteins/genetics* ; Child ; Cytoskeletal Proteins/genetics* ; Humans ; Infant ; Male ; Mitochondrial Myopathies ; Mutation ; Neurodegenerative Diseases ; Whole Exome Sequencing

BACKGROUND/OBJECTIVES: The NAD+ precursor nicotinamide riboside (NR) is a type of vitamin B3 found in cow's milk and yeast-containing food products such as beer. Recent studies suggested that NR prevents hearing loss, high-fat diet-induced obesity, Alzheimer's disease, and mitochondrial myopathy. The objective of this study was to investigate the effects of NR on inflammation and mitochondrial biogenesis in AML12 mouse hepatocytes. MATERIALS/METHODS: A subset of hepatocytes was treated with palmitic acid (PA; 250 µM) for 48 h to induce hepatocyte steatosis. The hepatocytes were treated with NR (10 µM and 10 mM) for 24 h with and without PA. The cell viability and the levels of sirtuins, inflammatory markers, and mitochondrial markers were analyzed. RESULTS: Cytotoxicity of NR was examined by PrestoBlue assay. Exposure to NR had no effect on cell viability or morphology. Gene expression of sirtuin 1 (Sirt1) and Sirt3 was significantly upregulated by NR in PA-treated hepatocytes. However, Sirt1 activities were increased in hepatocytes treated with low-dose NR. Hepatic pro-inflammatory markers including tumor necrosis factor-alpha and interleukin-6 were decreased in NR-treated cells. NR upregulated anti-inflammatory molecule adiponectin, and, tended to down-regulate hepatokine fetuin-A in PA-treated hepatocytes, suggesting its inverse regulation on these cytokines. NR increased levels of mitochondrial markers including peroxisome proliferator-activated receptor γ coactivator-1α, carnitine palmitoyltransferase 1, uncoupling protein 2, transcription factor A, mitochondrial and mitochondrial DNA in PA-treated hepatocytes. CONCLUSIONS: These data demonstrated that NR attenuated hepatic inflammation and increased levels of mitochondrial markers in hepatocytes.
Adiponectin ; alpha-2-HS-Glycoprotein ; Alzheimer Disease ; Animals ; Beer ; Carnitine O-Palmitoyltransferase ; Cell Survival ; Cytokines ; DNA, Mitochondrial ; Fatty Liver ; Gene Expression ; Hearing Loss ; Hepatocytes ; Inflammation ; Interleukin-6 ; Mice ; Milk ; Mitochondria ; Mitochondrial Myopathies ; Niacin ; Niacinamide ; Obesity ; Organelle Biogenesis ; Palmitic Acid ; Peroxisomes ; Sirtuin 1 ; Sirtuins ; Transcription Factors ; Tumor Necrosis Factor-alpha

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

BACKGROUND: Abnormally activated mechanistic target of rapamycin (mTOR) pathway has been reported in several model animals with inherited metabolic myopathies (IMMs). However, the profiles of mTOR pathway in skeletal muscles from patients are still unknown. This study aimed to analyze the activity of mTOR pathway in IMMs muscles. METHODS: We collected muscle samples from 25 patients with mitochondrial myopathy (MM), lipid storage disease (LSD) or Pompe disease (PD). To evaluate the activity of mTOR pathway in muscle specimens, phosphorylation of S6 ribosomal protein (p-S6) and p70S6 kinase (p-p70S6K) were analyzed by Western blotting and immunohistochemistry. RESULTS: Western blotting results showed that p-p70S6K/p70S6K in muscles from LSD and MM was up-regulated when compared with normal controls (NC) (NC vs. LSD, U = 2.000, P = 0.024; NC vs. MM: U = 6.000, P = 0.043). Likewise, p-S6/S6 was also up-regulated in muscles from all three subgroups of IMMs (NC vs. LSD, U = 0.000, P = 0.006; NC vs. PD, U = 0.000, P = 0.006; NC vs. MM, U = 1.000, P = 0.007). Immunohistochemical study revealed that p-S6 was mainly expressed in fibers with metabolic defect. In MM muscles, most p-S6 positive fibers showed cytochrome C oxidase (COX) deficiency (U = 5.000, P = 0.001). In LSD and PD muscles, p-S6 was mainly overexpressed in fibers with intramuscular vacuoles containing lipid droplets (U = 0.000, P = 0.002) or basophilic materials (U = 0.000, P = 0.002). CONCLUSION The mTOR pathway might be activated in myofibers with various metabolic defects, which might provide evidence for mTOR inhibition therapy in human IMMs.
Adolescent ; Adult ; Aged ; Blotting, Western ; Child ; Child, Preschool ; Female ; Glycogen Storage Disease Type II ; genetics ; metabolism ; Humans ; Immunohistochemistry ; In Vitro Techniques ; Lipid Metabolism, Inborn Errors ; genetics ; metabolism ; Male ; Middle Aged ; Mitochondrial Myopathies ; genetics ; metabolism ; Muscular Diseases ; genetics ; metabolism ; Signal Transduction ; genetics ; physiology ; TOR Serine-Threonine Kinases ; metabolism ; Young Adult

Clevudine was approved as an antiviral agent for hepatitis B virus, which showed marked, rapid inhibition of virus replication without significant toxicity. However, several studies have reported myopathy associated with clevudine therapy. Also, we experienced seven patients who suffered from myopathy during clevudine therapy. To characterize clevudine-induced myopathy, we collected previously reported cases of clevudine myopathy and analyzed all the cases including our cases. We searched electronic databases that were published in English or Korean using PubMed and KoreaMed. Ninety-five cases with clevudine myopathy, including our seven cases, were selected and analyzed for the demographic data, clinical features, and pathologic findings. The 95 patients with clevudine-induced myopathy comprised 52 women and 43 men aged 48.9 years (27–76 years). The patients received clevudine therapy for about 14.2 months (5–24 months) before the development of symptoms. Weakness mainly involved proximal extremities, especially in the lower extremities, and bulbar and neck weakness were observed in some cases (13.7%). Creatine kinase was elevated in the majority of patients (97.9%). Myopathic patterns on electromyography were observed in most patients examined (98.1%). Muscle biopsy presented patterns compatible with mitochondrial myopathy in the majority (90.2%). The weakness usually improved within about 3 months after the discontinuation of clevudine. Though clevudine has been known to be safe in a 6-month clinical trial, longer clevudine therapy for about 14 months may cause reversible mitochondrial myopathy. Careful clinical attention should be paid to patients with long-term clevudine therapy.
Biopsy ; Creatine Kinase ; Electromyography ; Extremities ; Female ; Hepatitis B ; Hepatitis B virus ; Humans ; Lower Extremity ; Male ; Mitochondrial Myopathies* ; Muscular Diseases ; Neck ; Virus Replication

Electron Transport Complex IV ; analysis ; Humans ; Mitochondrial Myopathies ; enzymology ; Staining and Labeling ; Succinate Dehydrogenase ; analysis

Kearns-Sayre syndrome (KSS) is a rare mitochondrial myopathy that usually develops before 20 years of age. It demonstrates multisystemic involvement with a triad of cardinal features: progressive ophthalmoplegia, pigmentary retinopathy, and cardiac conduction abnormalities. In addition, patients might have cerebellar ataxia, a high content of protein in the cerebrospinal fluid, proximal myopathy, multiple endocrinopathies, and renal tubular acidosis. We herein report the successful obstetric analgesic and anesthetic management of a 28-year-old parturient patient with KSS who required labor analgesia and proceeded to deliver by cesarean section. We extrapolate that regional analgesia/anesthesia might be beneficial for reducing the metabolic demands associated with the stress and pain of labor in patients with KSS. Efficient postoperative analgesia should be provided to decrease oxygen requirements.
Acidosis, Renal Tubular ; Adult ; Analgesia ; Anesthesia, Obstetrical* ; Cerebellar Ataxia ; Cerebrospinal Fluid ; Cesarean Section ; Female ; Humans ; Kearns-Sayre Syndrome* ; Mitochondrial Myopathies ; Muscular Diseases ; Ophthalmoplegia ; Oxygen ; Pregnancy ; Retinitis Pigmentosa

Kearns-Sayre syndrome (KSS) is a rare mitochondrial myopathy that usually develops before 20 years of age. It demonstrates multisystemic involvement with a triad of cardinal features: progressive ophthalmoplegia, pigmentary retinopathy, and cardiac conduction abnormalities. In addition, patients might have cerebellar ataxia, a high content of protein in the cerebrospinal fluid, proximal myopathy, multiple endocrinopathies, and renal tubular acidosis. We herein report the successful obstetric analgesic and anesthetic management of a 28-year-old parturient patient with KSS who required labor analgesia and proceeded to deliver by cesarean section. We extrapolate that regional analgesia/anesthesia might be beneficial for reducing the metabolic demands associated with the stress and pain of labor in patients with KSS. Efficient postoperative analgesia should be provided to decrease oxygen requirements.
Acidosis, Renal Tubular ; Adult ; Analgesia ; Anesthesia, Obstetrical* ; Cerebellar Ataxia ; Cerebrospinal Fluid ; Cesarean Section ; Female ; Humans ; Kearns-Sayre Syndrome* ; Mitochondrial Myopathies ; Muscular Diseases ; Ophthalmoplegia ; Oxygen ; Pregnancy ; Retinitis Pigmentosa

Myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is a multisystem clinical syndrome manifested by mitochondrial myopathy, encephalopathy, lactic acidosis and recurrent stroke-like episodes. A 27-year-old female with MELAS syndrome presented with cerebral infarction. Echocardiography revealed a thrombus attached to the apex of the hypertrophied left ventricle, with decreased systolic function. The embolism of the intracardiac thrombus might have been the cause of stroke. There should be more consideration given to the increased possibility of intracardiac thrombus formation when a MELAS patient with cardiac involvement is encountered.
Acidosis, Lactic ; Cerebral Infarction ; Echocardiography ; Embolism ; Female ; Heart ; Heart Ventricles ; Humans ; MELAS Syndrome ; Mitochondrial Myopathies ; Muscular Diseases ; Stroke ; Thrombosis

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