The mechanism of action of mitochondrial dysfunction in the development of non-alcoholic fatty liver disease / 临床肝胆病杂志

Nonalcoholic fatty liver disease （NAFLD） has gradually become the main reason affecting human liver health， and many factors are involved in the development and progression of NAFLD. Mitochondria， as the “energy factory” of cells， plays an important role in maintaining normal physiological functions. Studies have shown that hepatic mitochondrial dysfunction promotes the development and progression of NAFLD. This article briefly introduces the latest research advances in the basic characteristics and physiological function of liver mitochondria and reviews new research findings in the association of mitochondrial dysfunction with obesity， simple fatty liver disease， and nonalcoholic steatohepatitis， in order to provide new ideas for the research on targeted mitochondrial therapy for NAFLD.

Multiple mitochondrial dysfunction syndrome 2 caused by BOLA3 gene mutation: a case report and literature review / 中华神经科杂志

Objective:To report cases of multiple mitochondrial dysfunction syndrome 2 (MMDS2) caused by BOLA3 gene mutation, hoping to help clinical diagnosis. Methods:The medical records of a child with MMDS2 admitted to the Department of Neurology, Guangzhou Women and Children′s Medical Center in November 2021 were analyzed, and the clinical, imaging characteristics and prognosis of MMDS2 were summarized by literature review.Results:This 1 year and 9 months old male had a disease that started in childhood, with motor function regression and hyperlactatemia. Head magnetic resonance imaging indicated white matter lesions, and gene examination indicated the homozygous variation of BOLA3 gene c.295C>T(p.Arg99Trp). The diagnosis of MMDS2 was clear for the child. After treatment, the clinical symptoms and imaging of the child recovered significantly. Through literature review, 13 children with MMDS2 reported in 7 English literatures were reviewed. These cases had similar manifestations with the case reported in this study. Among them, 1 case recovered and 8 cases died in infancy. Conclusions:MMDS2 patients often show nervous system dysfunction such as motor regression, elevated lactate and white matter lesions, which often cause multiple system disorders. Some children die early, but some of them can be recovered.

17β-hydroxysteroid dehydrogenase 10 deficiency: a case report and literature review / 中国新生儿科杂志

Objective:To study the clinical and genetic characteristics of 17β-hydroxysteroid dehydrogenase 10 (HSD17B10) deficiency.Methods:The clinical data of a male patient with HSD17B10 deficiency diagnosed and treated in the neonatal department of our hospital were analyzed. Literatures were searched in the CNKI, VIP Database, WanFang Database PubMed and Embase using "17β-hydroxysteroid dehydrogenase", "17β-HSD", "17β-hydroxyl Steroid dehydrogenase 10", "HSD17B10", "2-methyl 3-hydroxybutyryl-CoA dehydrogenase", "2-methyl 3-hydroxybutyryl-CoA dehydrogenase deficiency", "MHBD", "MHBDD" as keywords. The reported data of patients with HSD17B10 deficiency were reviewed and the clinical and genetic characteristics analyzed.Results:The male newborn admitted to our hospital had poor response as the presenting symptom, accompanied with severe metabolic acidosis, myocardial injury and hyperammonemia. He was dead after giving up treatment. Genetic tests indicated mutations occur in HSD17B10 gene exon6. c.740A>G (P.N247S). A total of 41 cases (our case included) with 16 different types of gene mutations from 38 papers were analyzed. Most of the patients ( n=38, 92.7%) were male and the disease was more severe in male patients. Most patients had neurological abnormalities ( n=37, 90.2%) with comorbidities including metabolic acidosis ( n=13, 31.7%), hypoglycemia ( n=8, 19.5%), retinopathy ( n=7, 17.1%), cardiomyopathy ( n=6, 14.6%) and nystagmus ( n=4, 9.8%). Severe metabolic acidosis was the main presentation of the neonatal-onset of the disease. The younger the age of onset, the higher the mortality and the worse the prognosis. HSD17B10 gene mutation analysis could confirm the diagnosis. Conclusions:HSD17B10 deficiency gene mutations have multiple types. Male patients tend to have severe clinical courses and poor prognosis. No effective treatments exist to date. Family history of the disease strongly suggests early prenatal consultation and prenatal diagnosis.

A case of combined oxidative phosphorylation deficiency type 10 with tachypnea as first manifestation / 中华围产医学杂志

A term infant born small for gestational age presented with tachypnea as the first symptom one week after birth and had recurrent lactic acidosis. Whole-exome sequencing revealed compound heterozygous variants of c.1640C>T(p.A547V) and c.1274delG(p.G425Efs*23) in MTO1 gene, based on which the patient was diagnosed as combined oxidative phosphorylation deficiency type 10. The patient developed Klebsiella pneumoniae sepsis and died at 41 days of age. Combined oxidative phosphorylation deficiency type 10 is a type of mitochondrial disease inherited in an autosomal recessive manner. Patients with the onset of symptoms in the neonatal period are likely to have a poor prognosis and there is no effective treatment at present. The heterozygous variants of c.1640C>T and c.1274delG detected in this case are de novo variants, which expand the spectrum of variants in MTO1 gene.

Identification and functional analysis of combined oxidative phosphorylation deficiency 28 gene mutation / 中华内科杂志

Objective:To report a case of combined oxidative phosphorylation deficiency 28 (COXPD28) in China, identified the pathogenic mutation and explored the pathogenic mechanism preliminarily.Methods:The clinical characteristics of a patient with COXPD28 were retrospectively analyzed and the pathogenic mutations were identified by mitochondrial gene sequencing and whole exome sequencing. The wild-type and mutant plasmids of pathogenic genes were constructed, and effect of mutation on protein expression by quantitative real-time PCR (qPCR) and Western blot were evaluated. Statistical methods mainly used one-way ANOVA and LSD test.Results:A 21 year old female patient presented with lactic acid poisoning due to repeated chest distress and wheezing since childhood. The sequencing of the whole exon group gene found that solute carrier family 25 member 26 (SLC25A26) gene had a compound heterozygous mutation (c.34G>C, p.A12P; c.197C>A, p.A66E), which was the first report in China. In vitro function test showed that the expression levels of SLC25A26 mRNA and S-adenosylmethionine carrier (SAMC) protein in cells transfected with SLC25A26 mutant plasmid were significantly lower than those transfected with wild type plasmid. The p.A66E mutant plasmid reduced the expression level of SLC25A26 mRNA and SAMC protein to 6% and 26% of wild type plasmids respectively (both P<0.001), while p.A12P mutant plasmid decreased to 62% and 82% of wild type plasmids respectively ( P<0.001, P=0.044). When the double mutant (p.A66E+p.A12P) plasmids were co-transfected, the expression levels of SLC25A26 mRNA and SAMC protein decreased to 47% and 57% of the wild type plasmids, respectively ( P<0.001, P=0.001). Conclusion:The pathogenic mutation gene of this patient with COXPD28 is SLC25A26 gene mutation (p.A66E, p.A12P), which causes the decrease of SLC25A26 expression level, mitochondrial oxidative phosphorylation dysfunction, and induces COXPD28.

Molecular Diagnosis in an Argentinean Mitochondrial Disorders Cohort

Abstract Mitochondrial diseases are multisystemic disorders characterized by an impairment of the mitochondrial respiratory chain. Diagnosis requires an approach that involves a high index of suspicion, molecular techniques and a careful selection of the tissue to be studied. Our goal was to develop and implement local strategies for diagnosing mitochondrial disorders, by standardizing procedures of molecular biology and nucleic acid sequencing. A prospective, analytical, observational study was conducted in a cohort of, a total of 82 patients with suspected mitochondrial disorder who were treated at our hospital between May 2008 and June 2019. We developed molecular diagnostic tools that included classical monogenic techniques and Next Generation Sequencing. We characterized the neurological and extra neurological manifestations noted in our cohort. Following the proposed algorithm, we obtained a molecular diagnostic performance of 54%, identifying mutations in 44 patients. mtDNA mutations were identified in 34 patients. Structural rearrangements in mitochondrial genome were found in 3 and 7 in nuclear genes, respectively. Our results confirm the utility of the proposed algorithm and the molecular tools used, as evidenced by a high diagnostic performance. This is of great value to a more efficient and comprehensive medical care of patients and families affected by mitochondrial disorders.

Miopatia mitocondrial e deficiência auditiva neurossensorial: estudo de caso / Mitochondrial myopathy and sensorineural hearing loss: case study

Resumo A miopatia mitocondrial é causada pela ausência e/ou insuficiência de uma enzina quaternária, L-carnitina, responsável por transportar ácidos graxos livres para a parte interna da mitocôndria. A função da mitocôndria é produzir energia, contribuindo para o bom funcionamento das células. A Lipidose Muscular é uma doença que provoca anomalias em enzimas que metabolizam gordura e por consequência causa acúmulo de toxinas de subprodutos com gordura nos tecidos. O objetivo deste trabalho é apresentar o estudo de caso da paciente B.D., 37 anos, diagnosticada com Lipidose Muscular aos seis anos, com deficiência de L-Carnitina e relatar o acompanhamento fonoaudiológico realizado em um serviço de saúde auditiva. A abertura de prontuário da paciente foi realizada em 05/03/1989. Foi prescrito pelo neurologista o uso contínuo de 2g/dia de L-carnitina. A mãe relatou que B.D. apresentava dificuldades em ouvir, pois era muito desatenta, o que foi mais evidente quando começou a frequentar a escola. Em 1988, a paciente foi diagnosticada com perda auditiva neurossensorial de grau moderado bilateral e começou a fazer uso de aparelhos de amplificação sonora individual retroauriculares em 1989. O desempenho escolar e comunicação melhoraram. Em 1998, passou a utilizar aparelhos tipo micro canal, o que a favoreceu esteticamente, promoveu melhora da localização sonora e maior ganho em altas frequências. Os limiares de audibilidade apresentaram uma leve piora e a paciente atualmente é pós-graduada e trabalha em uma grande instituição financeira. Conclui-se que o diagnostico neurológico e a intervenção fonoaudiológica precoces possibilitaram o adequado desenvolvimento de linguagem da paciente.

Abstract Mitochondrial myopathy is caused by the absence and/or insufficiency of L-carnitine, a quaternary enzyme responsible for transporting free fatty acids into the mitochondria. The primary function of the mitochondria is to produce energy, contributing to proper cell functioning. Muscular lipidosis causes abnormalities in enzymes that metabolize fat, resulting in the accumulation of harmful amounts of fats in tissues. The aim of this study was to present the case study of patient B.D., a 37-year-old woman diagnosed with muscular lipidosis with L-carnitine deficiency at 6 years old, and describe the speech-language follow-up performed at a hearing care clinic. The first entry in the patient's medical chart was on 03/05/1989, with continuous use of 2g/day of L-carnitine prescribed by a neurologist. The mother reported that B.D. had difficulty hearing and was inattentive, which became more evident when she started school. In 1988 the patient was diagnosed with moderate bilateral sensorineural hearing loss and began using behind-the-ear (BTE) hearing aids in 1989, after which her academic performance and communication improved. In 1998 she switched to Completely in Canal (CIC) hearing aids, which are more discreet, provided better sound localization and greater high frequency gain, although her hearing thresholds worsened slightly. She completed her graduate studies and currently works at a large financial institution. It was concluded that early neurological diagnosis and speech-language intervention enabled adequate language development in the patient.

Leigh syndrome in an infant: autopsy and histopathology findings

Leigh syndrome is an inherited neurodegenerative disorder of infancy that typically manifests between 3 and 12 months of age. The common neurological manifestations are developmental delay or regression, progressive cognitive decline, dystonia, ataxia, brainstem dysfunction, epileptic seizures, and respiratory dysfunction. Although the disorder is clinically and genetically heterogeneous, the histopathological and radiological features characteristically show focal and bilaterally symmetrical, necrotic lesions in the basal ganglia and brainstem. The syndrome has a characteristic histopathological signature that helps in clinching the diagnosis. We discuss these unique findings on autopsy and radiology in a young infant who succumbed to a subacute, progressive neurological illness suggestive of Leigh syndrome. Our case highlights that Leigh syndrome should be considered in the differential diagnosis of infantile-onset, subacute neuroregression with dystonia and seizures, a high anion gap metabolic acidosis, normal ketones, elevated lactates in blood, brain, and urine, and bilateral basal ganglia involvement.

Research progress in cell and animal models of Leber hereditary optic neuropathy / 中华眼底病杂志

Leber hereditary optic neuropathy (LHON) is a blinding disease caused by mutations in mitochondrial DNA. It is a classic disease model for studying mitochondrial abnormalities. Its main mutation sites are m11778G.A, m.3460G.A and m.14484T.C. LHON cell models are mainly produced by lymphoblasts, fibroblasts, cell hybrids and induced pluripotent stem cells, while LHON animal models are mainly mice, which are produced by rotenone and ND4 mutants. Although the research on the LHON model has achieved good results, there are still many difficulties in constructing an ideal experimental model, which severely limit the exploring to the pathogenesis and therapeutic drugs of LHON. A detailed understanding of the application and characteristics of existing models in LHON will help improve experimental design and construct new models.

Post-transcriptional Processing and Modification of Mitochondrial RNA and Their Relationship with Human Mitochondrial Diseases / 中国生物化学与分子生物学报

Mitochondria are important organelles involved in energy generation and material metabolism in eukarvotic cells, and have their own genomic DNA.The regulation of mitochondrial gene expression is essential for the maintenance of mitochondrial function.According to the central law of molecular biology, genetic information is transferred from DNA to UNA, and then from RNA to proteins.Mitochondrial DNA (mtDNA) encodes 13 messenger RNAs (mRNAs) , 2 ribosomal RNAs (rRNAs) , and 22 transfer RNAs (tRNAs).The various precursor RNAs synthesized during transcription often have to undergo subsequent changes to transform into active mature RNA molecules, which is called "post-transcriptional processing and modification" .Herein we review the post-transcriptional processing and modification methods of the three RNAs encoded by the mammalian mitochondrial genome, and further explore the relationship between mammalian mitochondrial RNA post-transcriptional modification and mitochondrial diseases from the perspective of modification sites and modification enzymes.We aim to provide new ideas for the diagnosis and treatment of human mitochondrial diseases.

Anticuerpos antimitocondriales y anticuerpos contra antígenos extraíbles del núcleo en pacientes con cirrosis biliar primaria / Antimitochondrial Antibodies and antibodies against extractable nucleus antigens in patients with primary biliary cirrhosis

Resumen Objetivo: Determinar la frecuencia de anticuerpos antimitocondriales y de anticuerpos contra antígenos extraíbles del núcleo en pacientes con cirrosis biliar primaria. Material y métodos: Estudio de tipo cuantitativo, observacional y transversal, realizado en el Servicio de Inmunología del Hospital Nacional Arzobispo Loayza entre enero 2018 y marzo 2019. Se revisaron las historias clínicas de 30 pacientes con características presuntivas de cirrosis biliar primaria; para la detección de los anticuerpos antinucleares y anticuerpos antimitocondriales se empleó el kit inmunológico en sangre y observación con microscopio de inmunofluorescencia a 40X y para la detección de los anticuerpos contra antígenos extraíbles del núcleo se empleó el método Immunoblot. Resultados: Se estudiaron 30 pacientes con cirrosis biliar primaria, 20 fueron de sexo femenino (66,7%). El patrón de tinción más frecuente fue el citoplasmático moteado reticular en 17(56,7%), seguido del patrón citoplasmático moteado reticular y patrón moteado en 7(23,3%) pacientes, y en menor frecuencia el patrón citoplasmático moteado reticular y patrón centromérico. Nueve (42,9%) pacientes con cirrosis biliar primaria tenían anti-M2. Se demostró mayor frecuencia, 21(70%) de los pacientes con cirrosis biliar primaria tenían anticuerpos antimitocondriales. Conclusiones: Se encontró alta frecuencia de patrón citoplasmático moteado reticular en pacientes con cirrosis biliar primaria, se demostró asociación significativa con los anti-M2 y anticuerpos antimitocondriales.

Summary Objective: To determine the frequency of antimitochondrial antibodies and antibodies against extractable nucleus antigens in patients with primary biliary cirrhosis. Methods : A quantitative, observational and cross-sectional study was carried out at the Immunology Service of the Arzobispo Loayza National Hospital between January 2018 and March 2019. The medical records of 30 patients with presumptive characteristics of primary biliary cirrhosis were reviewed; for the detection of the antinuclear antibodies and antimitochondrial antibodies, the immunological kit was used in blood and observation with a 40X immunofluorescence microscope, and the Immunoblot method was used for the detection of the antibodies against extractable nucleus antigens. Results: Thirty patients with primary biliary cirrhosis disease were studied, 20 were female (66.7%). The most frequent staining pattern was the reticular mottled cytoplasmic in 17 (56.7%), followed by the reticular mottled cytoplasmic pattern and mottled pattern in 7 (23.3%) patients, and less frequently the reticular mottled cytoplasmic pattern and centromeric. Nine (42.9%) patients with primary biliary cirrhosis had anti-M2. In the present investigation, a higher frequency was demonstrated, 21 (70%) of the patients with primary biliary cirrhosis had antimitochondrial antibodies. Conclusions: A high frequency of reticular mottled cytoplasmic pattern was found in patients with primary biliary cirrhosis; a significant association with anti-M2 and antimitochondrial antibodies was demonstrated.

Identification of a novel mutation in the BCS1L gene causing Bj(o)rnstad syndrome / 中华皮肤科杂志

Objective To identify gene mutations in the BCS1L gene in a patient with Bj(o)rnstad syndrome mainly manifesting as congenital pili torti and sensorineural hearing loss.Methods Clinical data were collected and DNA was extracted from the peripheral blood of the patient and her parents.All the exons and their flanking sequences of the BCS1L gene were amplified by PCR followed by Sanger sequencing,and the sequencing results were compared with the normal sequences.A few hairs were collected from the patient,and examined by the scanning electron microscope.Results There were two mutations in BCS1L gene in the patient,i.e.,a heterozygous nonsense mutation in exon 4 and a heterozygous missense mutation in exon 8.The nonsense mutation in exon 4,which caused a change from CGA to TGA at position 144 and resulted in the substitution of arginine by termination codon (p.R144*),was a novel mutation in the BCS1L gene causing Bj(o)rnstad syndrome,and had never been repotted in the literature.The missense mutation in exon 8 led to a change from CGC to CAC at position 306 and resulted in the substitution of arginine by histidine (p.R306H).The patient's mother only carried a heterozygous mutation c.430 C＞T (p.R144*) in exon 4 of the BCS1L gene,and her father only carried a heterozygous mutation c.917 G＞A (p.R306H) in exon 8 of the BCS1L gene.Scanning electron microscopy showed that flats,grooves and longitudinal twisting irregu larly appeared at intervals on the surface of hair shafts.Conclusions A novel mutation in the BCS1L gene,which causes a change from CGA to TGA at position 144 in the BCS1L gene and results in a premature termination codon,is firstly reported in a patient with Bj(o)rnstad syndrome,and the compound heterozygous mutations c.430 C＞T and c.917 G＞A in the BCS1L gene are associated with the clinical manifestations of the patient.Genetic analvsis is helpful for the diagnosis of Bj(o)rnstad syndrome.

Neumopatía crónica secundaria al trastorno de la deglución en un paciente con miopatía mitocondrial / Chronic pneumopathy secondary to swallowing disorder in a patient with mitochondrial myopathy

RESUMEN Introducción: la enfermedad pulmonar crónica secundaria a la disfagia es una complicación frecuente en los pacientes con enfermedades neuromusculares. Las miopatías mitocondriales son un conjunto de enfermedades que pueden conducir a daño pulmonar progresivo, secundario al síndrome aspirativo crónico. Caso clínico: niño de 7 años con signos clínicos y radiológicos de enfermedad pulmonar crónica; además, con desnutrición crónica, debilidad muscular, disfonía y oculoparesia externa crónica multiplanar. Su padre tuvo síntomas similares desde la infancia y requirió alimentación con dieta espesa por trastorno de la deglución. Se confirma en el paciente la presencia de disfagia como la causa de la neumopatía crónica y se sospecha miopatía congénita hereditaria. En consecuencia, se realiza el diagnóstico de enfermedad mitocondrial con oculoparesia externa crónica, mediante la secuenciación del gen polimerasa gamma del ADN mitocondrial (POLG). Conclusiones: en los pacientes con neumopatía crónica se deben considerar las enfermedades neuromusculares en el diagnóstico diferencial. La miopatía mitocondrial con oculoparesia externa crónica progresiva, se asocia con trastorno de la deglución hasta en un 50 % de los casos. El diagnóstico temprano es importante para retardar el deterioro de la función pulmonar.

SUMMARY Introduction: Chronic lung disease secondary to dysphagia is a frequent complication in patients with neuromuscular diseases. Mitochondrial myopathies could lead to progressive lung damage due to chronic aspiration syndrome. Clinical case: Seven-year-old male with clinical and radiological signs of chronic lung disease, as well as low weight, weakness, dysphonia and multiplanar external oculoparesis. His father had similar symptoms during infancy and needed thickened liquid diet due to swallowing disorder. Dysphagia was confirmed as the cause of chronic lung disease and, therefore, hereditary congenital myopathy was suspected. Mitochondrial disease with chronic external oculoparesis was confirmed by molecular sequencing of the mitochondrial DNA gamma polymerase gene (POLG). Conclusion: Neuromuscular disorders may cause chronic lung disease. Mitochondrial myopathy with progressive chronic external oculoparesis is associated with swallowing disorder in 50 % of the cases. Early diagnosis is important to slow decline in lung function.

Infección asociada a catéter por Leclercia adecarboxylata y Raoultella ornithinolytica en un paciente con enfermedad mitocondrial / Leclercia adecarboxylata and Raoultella ornithinolytica catheter-related infection in a child with mitocondrial disease

Leclercia adecarboxylata y Raoultella ornithinolytica constituyen bacterias Gram-negativas emergentes. Los casos descritos son excepcionales. En los últimos años, las mejoras en las técnicas de diagnóstico microbiológico han permitido su detección y conocimiento. Se presenta el caso de un niño de 11 años con enfermedad mitocondrial, portador de catéter venoso central de larga duración, que desarrolló dos episodios de sepsis por L. adecarboxylata y R. ornithinolytica, respectivamente. En los casos de infección asociada al uso de catéter, es posible, en ocasiones, el tratamiento sin su retirada con evolución favorable. Es importante reconocer L. adecarboxylata y R. ornithinolytica como patógenos de diagnóstico cada vez más frecuentes, sobre todo, en pacientes inmunodeprimidos o con patologías crónicas asociadas.

Leclercia adecarboxylata and Raoultella ornithinolytica are emergent Gram-negative bacteria. Infections caused by these microorganisms are exceptional. Improvement of microbiologist techniques in the last years has enabled their detection and more accurate knowledge. We present the case of an 11-year-old boy with mitochondrial disease with a longterm central catheter who suffered from two sepsis caused by L. adecarboxylata and R. ornithinolytica, respectively. In catheter-related infections, sometimes it is possible to provide antimicrobial treatment without removal of catheter with good results, as in our patient. It is important to recognize L. adecarboxylata and R. ornithinolytica like increasingly frequent pathogenic bacteria, mostly in immunocompromised or chronic patients.

Cell models and drug discovery for mitochondrial diseases / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Mitochondrion is a semi-autonomous organelle, important for cell energy metabolism, apoptosis, the production of reactive oxygen species (ROS), and Ca2+ homeostasis. Mitochondrial DNA (mtDNA) mutation is one of the primary factors in mitochondrial disorders. Though much progress has been made, there remain many difficulties in constructing cell models for mitochondrial diseases. This seriously restricts studies related to targeted drug discovery and the mechanism and therapy for such diseases. Here we summarize the characteristics of patient-specific immortalized lymphoblastoid cells, fibroblastoid cells, cytoplasmic hybrid (cybrid) cell lines, and induced pluripotent stem cells (iPSCs)-derived differentiation cells in the study of mitochondrial disorders, as well as offering discussion of roles and advances of these cell models, particularly in the screening of drugs.

Clinical and genetic characteristics of 62 children with mitochondrial epilepsy / 中华儿科杂志

Objective@#To summarize the clinical and genetic characteristics of children with mitochondrial epilepsy.@*Methods@#Clinical data of 62 children who were clinically and genetically diagnosed with mitochondrial epilepsy by the Department of Neurology, Beijing Children′s Hospital from October 2011 to December 2018 were analyzed retrospectively, and the control of epilepsy was followed up. T test or χ2 test were used to analyze the related factors affecting the prognosis of epilepsy between the effective group and the ineffective group.@*Results@#Of the 62 patients, 33 were male and 29 were female. The age of onset was 3.38 (0-12.00) years; for the type of seizures, 68% (42/62) of the patients had focal seizures, generalized or secondary generalized tonic-clonic seizures were seen in 32% (20/62), myoclonic seizures in 23% (14/62), spastic seizures in 7 cases, tonic seizures in 4 cases, absence seizure, atonic seizure and clonic seizure in 1 case each; 16 cases (26%) had status epilepticus, of whom 6 cases had epilepsia partialis continua; 52% (32/62) had 2 or more types of seizures. The clinical phenotypes were mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) in 29 cases, Leigh syndrome (LS) in 11 cases, combined oxidative phosphorylation deficiency in 6 cases, myoclonus epilepsy with ragged-red fibers in 5 cases, Alpers syndrome in 4 cases, pontocerebellar hypoplasia type 6 and mitochondrial DNA depletion syndrome 9 in 2 cases each, mitochondrial complex Ⅰ deficiency nuclear type 20, progressive cavitating leukoencephalopathy, and biotinidase deficiency in 1 case each. Of the 62 cases, 40 cases (65%) had mitochondrial DNA (mtDNA) variations, of which 26 cases had m.3243A>G variants, 6 cases had m.8344A>G variants, and 3 cases had m.8993T>G/C variants, m.3271T>C, m.3481G>A, m.3946G>A, m.13094T>C, m.14487T>C variant was in 1 case each; nuclear DNA (nDNA) variations were identified in 22 cases (35%), of which 7 cases carrying variations in mitochondrial ammonia acyl tRNA synthetase coding gene, mutations in POLG and the gene encoding complex Ⅰ were in 4 cases each, variations in SUCLG1 and SDHA genes were in 2 cases each, and variations in PDHA1, BTD and TRIT1 genes were in 1 case each. Forty-three patients were followed up, and the follow-up time was 20 (3-84) months. According to the follow-up results, the anti-epilepsy treatment was effective in 19 cases (44%) and ineffective in other 24 cases (56%). The onset age of the effective group was 3.42 (0-11.50) years and that of the ineffective group was 0.92 (0-9.50) years. The onset duration of the effective group was 0 (0-7.00) years and that of the ineffective group was 0 (0-4.83) years. There was no significant difference between the effective group and the ineffective group (t=1.662, 0.860; P=0.104, 0.395). In the effective group and the ineffective group, 12 cases and 9 cases used less than 2 kinds of antiepileptic drugs, 7 cases and 15 cases used more than or equal to 2 kinds of antiepileptic drugs, 13 and 15 cases had first epilepsy, 6 and 9 cases had non-first epilepsy, 14 and 11 cases had mtDNA variation, 5 and 13 cases had nDNA variation, respectively. There was no significant difference between the two groups (χ2=2.794, 0.164, 3.380; P=0.095, 0.686, 0.066).@*Conclusions@#The types of seizures with mitochondrial epilepsy in children varied, with focal motor seizures being the most common, followed by generalized or secondary generalized tonic-clonic seizures. Most children have more than two types of seizures. MELAS is the most common clinical phenotype, followed by LS; mtDNA variation is the dominant gene variation, of which m.3243A>G variation is the most common hotspot variation, followed by gene variation encoding mitochondrial aminoacyl tRNA synthase.

Neurological mitochondrial diseases / 中华神经科杂志

Mitochondrial disease (MD) is a group of metabolic disorders,caused by mitochondrial DNA or nuclear DNA mutations.With the development of research in mitochondrial medicine,the phenotypic spectrum of MD has expanded significantly.The common phenotypes in Chinese population included mitochondrial encephalopathy with lactic acidosis and stroke like episodes,Leigh syndrome,Leber hereditary optic neuropathy and chronic progressive external ophthalmoplegia.The rare phenotype included myoclonic epilepsy with ragged-red fibers,Kearns-Sayre syndrome,sensory ataxic neuropathy,mitochondrial neurogastrointestinal encephalomyopathy,Alpers disease,limb girdle mitochondrial myopathy,neuropathy with ataxia and retinitis pigmentosa.However,considerable clinical variability exists and some individuals do not fit into the known disease category.The revolution in genetic technologies has dramatically improved the diagnosis strategy of MD.In this article the pathology,clinical symptoms,laboratory findings and therapy in MD are sumarrized so as to provide guidance for clinical practice.

Sudden death due to mitochondrial diseases / 中国实用儿科杂志

Sudden unexpected death means a "healthy" person died suddenly of unknown diseases,usually within 6 hours after onset. It is reported that sudden unexpected death occurred from neonates(sudden infant death syndrome)to adults(sudden adult death syndrome). The patients suddenly died during daily activities,sleep or exercise. Underlying genetic diseases are main cause of sudden death. The etiological studies are performed in the patients of sudden death. Heart attack and encephalopathy due to varied genetic disorders are the two major causes. Sudden cardiac death accounts for more than half. It is known that some inherited metabolic diseases associated with sudden death sometimes. Mitochondrial diseases are a group of inherited metabolic diseases. Some patients of mitochondrial diseases suddenly died of acute heart failure,malignant arrhythmia or encephalopathy. With the advancement of genetic technology,post-mortem genetic diagnosis became available in some cases. The definite genetic diagnosis is the key for the genetic counseling of the families and prenatal diagnosis of their fetuses.

Cell models and drug discovery for mitochondrial diseases / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Mitochondrion is a semi-autonomous organelle, important for cell energy metabolism, apoptosis, the production of reactive oxygen species (ROS), and Ca homeostasis. Mitochondrial DNA (mtDNA) mutation is one of the primary factors in mitochondrial disorders. Though much progress has been made, there remain many difficulties in constructing cell models for mitochondrial diseases. This seriously restricts studies related to targeted drug discovery and the mechanism and therapy for such diseases. Here we summarize the characteristics of patient-specific immortalized lymphoblastoid cells, fibroblastoid cells, cytoplasmic hybrid (cybrid) cell lines, and induced pluripotent stem cells (iPSCs)-derived differentiation cells in the study of mitochondrial disorders, as well as offering discussion of roles and advances of these cell models, particularly in the screening of drugs.

Quantitation of muscle pathology abnormalities in 18 patients with mitochondrial disorders / Quantificação das anormalidades patológicas musculares em 18 pacientes com desordens mitocondriais

ABSTRACT INTRODUCTION: Mitochondrial disorders can lead to the accumulation of mitochondria in muscle fibers, as indicated by ragged red (RRF) or ragged blue fibers when stained with modified Gomori trichrome or succinate dehydrogenase (SDH+), respectively, and, absence of activity of cytochrome c oxidase, COX negative fibers (COX-). The combined COX-SDH stain (COMBO+) can reveal even more COX-deficient fibers. OBJECTIVE: To quantify RRFs, SDH+, COX-, and COMBO+ fibers in muscle biopsies with mitochondrial findings. MATERIAL AND METHODS: We retrospectively selected 18 muscle biopsies with mitochondrial abnormalities based on the Walker criteria (percentage of RRFs/COX- fibers, and clinical picture), and/or the Sleigh criteria (percentage of RRFs, SDH+, and COX- fibers). RESULTS: Females represented 83.3%, with a mean age of 38.6 years (5 months-70 years). Patients were diagnosed with chronic progressive external ophthalmoplegia (CPEO, 66.7%), proximal myopathy (22.2%), idiopathic hyperCKemia (11.1%), Kearns-Sayre syndrome (5.6%), mitochondrial encephalomyopathy with ragged red fibers and stroke-like episodes (5.6%), and a dystrophic pattern (5.6%). Some cases of CPEO were combined with proximal myopathy. The quantitative pathologic findings were: RRFs, 3.95% ± 3.17%; SDH+, 7.55% ± 6.1%; COX-, 10.9% ± 7.2%; COMBO+, 14.22% ± 12.79%. We found a slight variation in the diameter of muscle fibers, no necrosis or proliferative connective tissue, few fibers with internal nuclei, and some cases with fiber type grouping. CONCLUSION: Pathologic events, grouped in ascending order of frequency, were RRFs, SDH+ fibers, COX- fibers, and COMBO+ fibers. These data emphasize the importance of the COMBO technique in revealing occult COX deficiency in muscle fibers.

RESUMO INTRODUÇÃO: Desordens mitocondriais são usualmente caracterizadas por: 1. acúmulo de mitocôndria nas fibras musculares que aparecem como fibras vermelhas rasgadas (FVR) ou azuis rasgadas quando coradas, respectivamente, pelo tricrômio modificado de Gomori ou pelo succinato desidrogenase (SDH+); 2. ausência de atividade da citocromo c oxidase (COX), originando fibras COX negativa (COX-). A combinação de colorações COX e SDH pode revelar ainda mais fibras COX deficiente (COMBO+). Objetivos: Quantificar FVR, SDH+, COX- e COMBO+ em biópsias musculares com anormalidades mitocondriais. MATERIAL E MÉTODOS: Foram analisadas retrospectivamente 18 biópsias com anormalidades mitocondriais com base no critério de Walker (percentagem de FVR/ COX- e quadro clínico) e/ou critério de Sleigh (percentagem de FVR, SDH+ e COX-). RESULTADOS: Sexo feminino representou 83, 3% e média de idade 38, 6 anos (5 meses a 70 anos). Oftalmoplegia externa progressiva crônica (OEPC) representou 66, 7%; miopatia proximal, 22, 2%; hiperCKemia idiopática, 11, 1%; síndrome de Kearns-Sayre, 5, 6%; encefalopatia mitocondrial com FVR e episódios semelhantes a acidente vascular cerebral, 5, 6%; e padrão distrófico, 5, 6%. Alguns casos de OEPC estavam associados à miopatia proximal. Achados patológicos quantitativos: FVR, 3, 95% ± 3, 17%; SDH+, 7, 55% ± 6, 1%; COX-, 10, 9% ± 7, 2%; COMBO+, 14, 22% ± 12, 79%. Encontramos leve variação de calibre das fibras musculares sem necrose ou proliferação de tecido conjuntivo, poucas fibras com núcleos internos e alguns casos com agrupamento de fibras. CONCLUSÃO: As anormalidades patológicas nas fibras musculares em ordem ascendente de frequência foram: FVR, SDH+, COX- e COMBO+. Nossos achados enfatizam a importância da técnica COMBO (COX + SDH) para aumento na frequência de fibras musculares COX deficiente ocultas.