Clinical, Neuroimaging, and Pathological Analyses of 13 Chinese Leigh Syndrome Patients with Mitochondrial DNA Mutations / 中华医学杂志(英文版)

Background@#Leigh syndrome (LS) is a rare disease caused by mitochondrial defects and has high phenotypic and genotypic heterogeneity. We analyzed the clinical symptoms, neuroimaging, muscular histopathology, and genotypes of 13 Chinese LS patients with mitochondrial DNA (mtDNA) mutations.@*Methods@#Mutations in mtDNA were identified by targeted sequencing. The brain imaging features on magnetic resonance imaging (MRI) were analyzed. The levels of lactate in fasting blood and cerebrospinal fluid (CSF) were routinely tested. The levels of urinary organic acids, plasma amino acids, and acylcarnitines were examined with gas chromatography-mass spectrometry and tandem mass spectrometry. The histopathological traits of skeletal muscles were analyzed under microscope.@*Results@#Among 13 patients, mutations of MT-NDs (n = 8) and MT-ATP6 (n = 4) genes were most common. Strabismus (8/13), muscle weakness (8/13), and ataxia (5/13) were also common, especially for the patients with late-onset age after 2 years old. However, respiratory distress was common in patients with early-onset age before 2 years old. The most frequently affected brain area in these patients was the brain stem (12/13), particularly the dorsal part of midbrain, followed by basal ganglia (6/13), thalamus (6/13), cerebellum (5/13), and supratentorial white matter (2/13). Besides, the elevated lactate levels in CSF (6/6) were more common than those in serum (7/13). However, the analysis of abnormal plasma amino acid and urinary organic acid showed limited results (0/3 and 1/4, respectively). Muscular histopathology showed mitochondrial myopathy in the three late-onset patients but not in the early-onset ones.@*Conclusions@#Noninvasive genetic screening is recommended for mtDNA mutations in MT-NDs and MT-ATP6 genes in patients with ophthalmoplegia, muscle weakness, ataxia, and respiratory disorder. Furthermore, the lactate detection in CSF and the brain MRI scanning are suggested as the diagnosis methods for LS patients with mtDNA mutations.

Mitochondrial proteomic profile of complex IV deficiency fibroblasts: rearrangement of oxidative phosphorylation complex/supercomplex and other metabolic pathways / Perfil proteómico mitocondrial de los fibroblastos con deficiencia del complejo IV: reordenamiento del complejo/supercomplejo de la fosforilación oxidativa y otras vías metabólicas

Abstract: Background: Mitochondriopathies are multisystem diseases affecting the oxidative phosphorylation (OXPHOS) system. Skin fibroblasts are a good model for the study of these diseases. Fibroblasts with a complex IV mitochondriopathy were used to determine the molecular mechanism and the main affected functions in this disease. Methods: Skin fibroblast were grown to assure disease phenotype. Mitochondria were isolated from these cells and their proteome extracted for protein identification. Identified proteins were validated with the MitoMiner database. Results: Disease phenotype was corroborated on skin fibroblasts, which presented a complex IV defect. The mitochondrial proteome of these cells showed that the most affected proteins belonged to the OXPHOS system, mainly to the complexes that form supercomplexes or respirosomes (I, III, IV, and V). Defects in complex IV seemed to be due to assembly issues, which might prevent supercomplexes formation and efficient substrate channeling. It was also found that this mitochondriopathy affects other processes that are related to DNA genetic information flow (replication, transcription, and translation) as well as beta oxidation and tricarboxylic acid cycle. Conclusions: These data, as a whole, could be used for the better stratification of these diseases, as well as to optimize management and treatment options.

Resumen: Introducción: Las mitocondriopatías son enfermedades multisistémicas que afectan el funcionamiento de la fosforilación oxidativa (OXPHOS). Un buen modelo de estudio para estas enfermedades es el cultivo primario de fibroblastos. En este trabajo se utilizaron fibroblastos con mitocondriopatía del complejo IV para determinar cuáles son las principales funciones afectadas en esta enfermedad. Métodos: Se realizaron cultivos primarios de fibroblastos para corroborar el fenotipo de la enfermedad. Las mitocondrias se aislaron de estas células y se extrajo su proteoma para su identificación. Las proteínas identificadas se validaron con la base de datos de MitoMiner. Resultados: Los fibroblastos conservaron el fenotipo de la enfermedad que incluye un defecto del complejo IV. El proteoma mitocondrial de estas células mostró que las proteínas más afectadas pertenecen al sistema de OXPHOS, principalmente los complejos que forman supercomplejos o respirosomas (I, III, IV y V). El defecto en el complejo IV al parecer se debió a problemas de ensamblaje que pueden evitar la formación de los supercomplejos y la eficiente canalización de sustratos. También se observó que esta mitocondriopatía afecta otros procesos relacionados con el flujo de información genética del DNA (replicación, transcripción y traducción), así como con la beta oxidación y el ciclo de los ácidos tricarboxílicos (TCA). Conclusiones: En conjunto, estos datos podrían utilizarse para una mejor clasificación de estas enfermedades, así como para la optimización de las opciones de manejo y tratamiento.

Clinical and laboratory survey of 65 Chinese patients with Leigh syndrome / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Leigh syndrome is an inherited neurodegenerative disease that emerges in infancy and childhood and presents with a clinically heterogeneous variety of neuromuscular and non-neuromuscular disorders. It can result from the inheritance of mutations in either nuclear or mitochondrial DNA. In the current study, we performed a retrospective study in 65 patients in order to investigate the clinical and genetic characteristics of Leigh syndrome in Chinese patients.</p><p><b>METHODS</b>Sixty-five unrelated cases (35 men and 30 women) who were hospitalized in the past 12 years were reviewed. Diagnosis was based on both the clinical presentation and the characteristic neuropathologic findings of bilateral symmetric necrotizing lesions in the basal ganglia and brain stem as detected using cranial computed tomography (CT) scan or magnetic resonance imaging (MRI). The differential diagnosis of organic acidurias and fatty acid beta-oxidation defects were performed. Specific point mutations and deletions in mitochondrial DNA (T8993G, T8993C, T9176C, A8344G, A3243G) were screened by PCR-restriction analysis and Southern blot. The SURF1 gene was sequenced. Skeletal muscle biopsies were performed in 17 (26.2%) of the patients. The diagnosis was confirmed by autopsy in 6 (9.2%) patients.</p><p><b>RESULTS</b>The patients had various forms of metabolic encephalomyopathy. Fifty-nine (90.8%) of the patients had the typical neuroradiological features of Leigh syndrome, including symmetrical necrotizing lesions scattered within the basal ganglia, thalamus and brain stem. Twenty (30.8%) patients were confirmed by genetic, biochemical analysis and autopsy. Specific point mutations in mitochondrial DNA were found in 5 cases (7.7%). Of these, the A8344G mutation was detected in 2 patients. The T8993G, T8993C, and A3243G point mutations were identified in 3 other patients, respectively. SURF1 mutations associated with cytochrome c oxidase deficiency were identified in 8 (12.3%) families by DNA sequencing. A G604C mutation was identified in 6 (9.2%) patients. The genotypes of 52 patients remained unknown.</p><p><b>CONCLUSIONS</b>Leigh syndrome presents as a diverse array of clinical features and can result from specific mutations in nuclear or mitochondrial DNA. In this study, SURF1 mutations associated with cytochrome c oxidase deficiency were identified in 8 (12.3%) out of 65 patients with Leigh syndrome. It indicates that SURF1 mutations might be a common cause of Leigh syndrome in China. The etiology of Leigh syndrome in Chinese patients represents a persistent challenge to clinicians.</p>

Respiratory chain activity in myopathies

Aim: The present study was conducted to find out whether disturbances of respiratory chain enzymes were involved in the pathogenesis of three types of myopathy: Duchenne muscle dystrophy [DMD], limb girdle muscular dystrophy, and steroid-induced myopathies; to assess the extent and nature of these deficits among the three myopathic groups, and to investigate the relation between the severity of muscular disorders- assessed by creatine phosphokinase [CPK] level- and the extent of respiratory chain impairment. Subjects and Fourty myopathic patients as group I [GI]; 10 DMD [GIA], 16 limb girdle dystrophy [GIB], and 14 steroid-induced myopathy [GIC]; and 20 healthy controls as group II [GII] that matches the general features of GI. Cases and controls were subjected to history taking as well as physical examination. Diagnosis of myopathy was established using routine motor and sensory conduction study and concentric needle EMG. Cases and controls were subjected to estimation of respiratory chain complexes; RCI, RCII, RCIII, and RCIV, in neutrophil mitochondria. Results were analysed using t-test between GI and II and F test in between GIA, GIB and GIC. The results revealed a significant decrease of all respiratory chain complexes; RCI, RCII, RCIII, and RCIV; in GI as compared to controls [2878.04 +/- 1085.96 versus 5867.93 +/- 1000.03 micro mol/min/mg protein for RCII, 549.7 +/- 21574 versus 80382+/=119.41 micro mol/min/mg of protein for RCIV, 60654 +/- 162.35 versus 95949 +/- 136.14 micro mol/min/mg of protein for RCIII, and 58.73 +/- 18.08 versus 97.88 +/- 19.06 micro mol/min/mg protein for RCIV. On comparing the 3 subgroups; IA, IB, and IC; the following was found [1] A significant decrease of GIC when compared to GIA and when compared to GIB and when compared to GIB as regards RCI [3234.526 +/- 716.363, 3385.13 +/- 218.603, and 2043.894 +/- 631.967 micro mol/min/mg protein for GIA. GIB, and GIC, respectively, F - 4.331, and P = 0.03]; [2] A significant decrease of GIA when compared to GIB and when compared to GIC as regards RCIV [42.584 +/- 22,9177, 66.947 +/- 10.861, and 60.88 +/- 1532 micro mol/min/mg protein for GIA, GIB, and GIC, respectively, F = 3.67 and P = 0.47]. [3] Nonsignificant difference between GIA, GIB and GIC as regards RCII, and RCIII. Using multiple linear regression analysis between respiratory chain enzymes and CPK, only RCIV showed a statistically significant correlation with CPK. Conclusions: Myopathy could be associated with alterations in respiratory chain enzyme complexes that result in effort intolerance. Such an alteration could be detected in neutrophil mitochondria by an easier noninvasive technique. RCIV could be used as a predictive marker for the occurrence of muscle damage in myopathy

Clinical Review of Severe Myoclonic Epilepsy in Infancy / 대한간질학회지

PURPOSE: Severe myoclonic epilepsy in infancy (SMEI) seems to be more common than realized, because it is often overlooked. In addition, the prognosis is poor despite of recent advances of antiepileptic treatment. This study is intended to provide better identification and treatment of SMEI by reviewing our experiences. METHOD: From April 1995 to September 2002, clinical and electrophysiologic features were reviewed for 18 patients with SMEI, who were diagnosed at epilepsy center, Inje University Sang-gye Paik Hospital. RESULTS: 1) Seizure onset age was 5.1+/-2.8 months (mean+/-SD) old. 2) Onset of febrile seizure was from 2 to 11 months of age (7.8+/-3.0 months) and febrile status epilepticus was also noted in 9 patients (50%). 3) Initial afebile seizure was noticed in 11 patients (61.1%). 4) Various types of seizures were manifested durign the patient's clinical courses 5) Myoclonic seizures were started from 7 to 48 months of age (26.5+/-12.1 months) and persisted in 14 (77.8%) patients. 6) Four patients (22.2%) had photosensitivity. 7) Mitochondrial cytopathy was suspected in 8 patients, and complex IV deficiency was confirmed in 1 patient. 8) Ketogenic diet was effective in 8 patients (61.5%) with seizure reduction more than 50% among 13 patients. 9) All sixteen patients who could be followed up for more than 12 months, showed normal initial development, and subsequently, all of them showed progressive delvelopmental delay with mild degree in 4 patients (22.2%), moderate degree in 7 patients (38.8%), and severe degree in 4 patients (22.2%). CONCLUSION: SMEI is one of the intractable childhood epileptic syndromes with variable clinical seizures and progressive developmental declining. SMEI should be paid more attention in epilepsy clinic for accurate diagnosis and adequate antiepileptic treatment including ketogenic diet.