Myo-leukoencephalopathy in twins: Study of 3243-myopathy,encephalopathy, lactic acidosis,and strokelike episodes mitochondrial DNA mutation

Two dizygotic twins with myopathy and leukoencephalopathy are described. The female twin had an incomplete from of MELAS syndrome (myopathy, encephalopathy, lactic acidosis, and strokelike episodes) with severe myopathy, epileptic seizures without strokelike episodes. The male twin presented clinical features exclusively of myopathy and subclinical leukoencephalopathy. The MELAS mitochondrial DNA point mutation (MELAS-3243) was found by southern blot and polymerase chain reaction in muscle, skin fibroblasts, and blood of the female twin and was not detected in the skin fibroblasts nor in the blood of the mother, nor in any of the tissues tested in the male twin. The absence of mutation in male twin tissues raises questions about the pathogenetic significance of the mutation in this family.     

Autopsied case with MERRF/MELAS overlap syndrome accompanied by stroke‐like episodes localized to the precentral gyrus

We present an autopsied case with A8344G‐mutated myoclonus epilepsy with ragged red fibers (MERRF)/mitochondrial encephalomyopathy with lactic acidosis and stroke‐like episodes (MELAS) overlap syndrome accompanied by stroke‐like episodes localized to the precentral gyrus. A 16‐year‐old Japanese woman suddenly experienced repetitive consciousness disturbances with increased serum lactate and creatine kinase levels. Magnetic resonance imaging showed abnormal intensity of bilateral precentral gyrus. She was clinically diagnosed as having a mitochondrial disorder and the A8344G mutation was detected in mitochondrial DNA. At 17 years of age, she died from congestive heart failure secondary to a third episode of lactic acidosis. Neuropatho‐logically, multifocal laminar necrosis, which is responsible for stroke‐like episodes in MELAS, was seen in the frontal cortex including the precentral gyrus, but there was no neuronal loss and gliosis in the basal ganglia, cerebellum, and brainstem, which were compatible with MERRF. Hypertrophy of the vascular smooth muscle and choroidal epithelium were seen, and were strongly visualized by an anti‐mitochondrial antibody. Skeletal muscles showed uneven muscular diameters, increased central nuclei, and ragged red fibers (RRFs). Decreased cytochrome c oxidase (COX) activity and strongly succinate dehydrogenase (SDH)‐reactive blood vessels were also noted. Stroke‐like episodes in MERRF/MELAS overlap syndrome are thought to be rare in the frontal cortex including the precentral gyrus. Only two cases of MERRF/MELAS overlap syndrome with A8344G mutation, including this case, have shown stroke‐like episodes in the frontal lobes. Other than the A8344G mutation and frontal lobe involvement, they had a high degree of similarity in terms of presence of RRFs, gastrointestinal dysfunction, and lack of typical MERRF neuropathology. In conclusion, this is an important case describing the clinical spectrum associated with A8344G‐mutated MERRF/MELAS overlap syndrome.     

Apoptosis is suspended in muscle of mitochondrial encephalomyopathies

Over the past few years, many studies have been done on the apoptotic involvement in muscle fiber degeneration in various myopathies, but the occurrence of apoptosis in muscles of mitochondrial encephalomyopathies is still controversial. To confirm whether apoptotic processes are truly related to muscle fiber degeneration in mitochondrial encephalomyopathies, we performed the TUNEL method not only at the light microscopic (LM) but also at the electron microscopic (EM) level for muscles of five MELAS, five CPEO and five MERRF patients and five control muscles. Immunohistochemical studies of Bcl-2, Bax, cytochrome c, Apaf-1, activated caspase-3 and human inhibitor of apoptosis protein XIAP, and immunoblotting of Apaf-1 and XIAP were also carried out. In LM-TUNEL, MELAS, CPEO and MERRF patients had only very small numbers of TUNEL-positive myonuclei: 0.13+/-0.10%, 0.15+/-0.14% and 0.04+/-0.09%, respectively. Almost all of them were seen in ragged-red fibers (RRFs). EM-TUNEL showed no significant increase of DNA fragmentation in RRFs despite mild peripheral chromatin condensation. However, Bax and Apaf-1 expression and cytochrome c release from mitochondria were seen in RRFs. Caspase-3 activation was confirmed in 9.0+/-3.7%, 12.0+/-4.4% and 12.4+/-3.8% of RRFs in MELAS, CPEO and MERRF, respectively, but not in control muscles. Almost all RRFs showed sarcoplasmic expression of XIAP. Thus, there is a possibility that, although apoptotic reactions started in muscles of mitochondrial encephalomyopathies, their execution is rarely completed. Sarcoplasmic expression of XIAP probably leads to the suspension of the apoptotic process in mitochondrial encephalomyopathies.     

线粒体脑肌病伴高乳酸血症和脑卒中样发作综合征一家系临床特征及线粒体基因A3243G位点点突变异质性水平

目的 调查1个疑似患有母系遗传性线粒体脑肌病伴高乳酸血症和脑卒中样发作(MELAS)综合征家系的临床表现、生物化学检测数据和影像学资料,并探索其与血细胞线粒体基因突变异质性水平的关联性.方法 收集先证者和11位其母系家系成员的一般情况、抽搐及脑卒中样发作等病史,检测家系成员的血常规和运动前后血浆乳酸水平等生化指标,并做头颅磁共振检查.用聚合酶链反应(PCR)-限制性内切酶片段长度多态和DNA测序法检测其成员是否存在线粒体基因组A3243G点突变,并用荧光实时定量PCR定量该突变的水平.结果 该家系部分成员存在抽搐、脑卒中样发作和高乳酸血症等MELAS综合征典型症状,以及身材矮小、运动不耐受和发热、偏头痛等非典型症状.发作期头颅磁共振成像符合MELAS综合征的典型特点,且普遍存在小脑萎缩.母系亲属均存在线粒体基因的A3243G位点点突变,突变异质性水平越高,症状越典型且严重.结论 该调查家系确诊母系遗传性MELAS综合征,其致病基因为线粒体A3243G点突变.外周血血细胞线粒体基因突变异质性水平与亲缘关系、抽搐早现性和血乳酸值等临床表型存在相关性.     

Apoptosis-related changes in skeletal muscles of patients with mitochondrial diseases

Much interest has recently been shown in apoptosis-mediated roles in the pathophysiology of mitochondrial diseases, because mitochondrial defects are implicated in a wide variety of degenerative diseases. We investigated whether apoptotic events occurred in skeletal muscles of patients with mitochondrial diseases, including chronic progressive external ophthalmoplegia (CPEO), Kearns-Sayer syndrome (KSS), and mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS). In a immunohistochemical study, stainings for 8-hydroxy-deoxyguanosine (8-OH-dG), 4-hydroxy-nonenal (4-HNE), Mn-SOD, Bcl-2, cytochrome c, DNase I and Bcl-x L showed a pronounced granular distribution in the cytochrome c oxidase (COX)-negative ragged-red fibers (RRFs). On the other hand, the signals for Bax, p53, Fas and caspase 3 were not obviously increased in RRFs. In situ labeling of DNA breaks demonstrated preferential signals not only in myonuclei but also in subsarcolemmal regions of RRFs, indicating that mitochondrial as well as myonuclear DNA is fragmented in RRFs. An immunoblotting study demonstrated that cytochrome c was increased in the cytosol of diseased muscles and that DNase I was increased in mitochondria, compared to that of normal muscles. No difference was observed between protein bands at 20 kDa corresponding to caspase 3 in diseased and normal muscles. These findings demonstrate that these mitochondrial diseases harbor unique apoptosis-related changes that differ from caspase 3-dependent apoptosis. It is thought that these changes are induced by superoxide overproduction and cytochrome c release resulting from an inherent mitochondrial defect and that the events are associated with DNase I activation.     

The mitochondrial DNA G13513A transition in ND5 is associated with a LHON/MELAS overlap syndrome and may be a frequent cause of MELAS

We report on 4 male patients with clinical, radiological, and muscle biopsy findings typical of the mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) phenotype. Skeletal muscle mitochondrial DNA (mtDNA) analysis showed that all patients harbored a heteroplasmic G13513A mutation in the ND5 subunit gene. One of these cases (Patient 1) presented with symptoms characteristic of Leber's hereditary optic neuropathy (LHON) 2 years before the first stroke-like episode. Quantitative analysis in several postmortem tissue sections showed that the relative proportions of mutant mtDNA were generally lower than those reported with other pathogenic mtDNA mutations. Single-fiber polymerase chain reaction studies demonstrated significantly higher amounts of mutant mtDNA in ragged red fibers (RRFs) compared with non-RRFs. This study indicates that the G13513A transition is likely to be pathogenic, that it can cause an LHON/MELAS overlap syndrome, and that it may be a more frequent cause of MELAS than previously recognized.     

A study of mitochondrial electron transfer chain in myotonic dystrophy

Ragged-red fibers (RRFs) are mainly seen in mitochondrial myopathy and related to biochemical defects in electron transfer chain on some occasions. Recently, some papers reported the occurrence of RRFs in the biopsied muscle of myotonic dystrophy (MyD). To examine whether the mitochondrial function is disturbed in MyD, we have studied the biopsied muscles of 12 cases with MyD (10 males and 2 females averaging 38 years of age) morphologically and mainly biochemically. RRFs, ranging from 2--20% of the muscle fibers, were identified in 5 out of 12 cases. On electron microscopy, these fibers had aggregated abnormally enlarged mitochondria with dene bodies, concentrically whirled membranous cristae and paracrystalline inclusions. Clinically, 4 of 5 cases with RRFs had mild to moderate and only 2 of 7 without RRFs had ophthalmoplegia. Bicycle ergometer exercise test showed abnormal increase of lactate/pyruvate ratio in three cases with RRFs. Histochemically, cytochrome c oxidase (CCO) activity was absent selectively in all of the RRFs. Immunohistochemical staining showed the presence of CCO protein by using monoclonal antibody which was specific to CCO subunit IV. Biochemical study with crude muscle extract of 11 cases of MyD showed decreases in NADH dehydrogenase, NADH CoQ reductase, succinate CoQ reductase (SCR), CCO, carnitine actyl transferase activities in most of cases regardless RRFs. To avoid the influence possibly derived from the various stages of muscle degeneration in the biopsied specimens, we calculated the ratio of the enzyme activities compared with succinate dehydrogenase which was located in the electron transfer chain and did not show any statistical difference regardless of RRFs.(ABSTRACT TRUNCATED AT 250 WORDS)     

A case of mitochondrial encephalomyopathy characterized by repeated stroke-like episodes

We reported a case of mitochondrial encephalomyopathy with repeated stroke-like episodes. A 33-year-old single male was admitted to our hospital because of stroke-like episodes with visual field defect, hemiplegia and convulsion repeated seven times for the past seven years. There were no abnormalities on the physical examination. He was hallucinative and perseverative and had mental deficiency. Muscle weakness and atrophy were not prominent, and generalized hyporeflexia were present without pathological reflexes. Myoclonus was not observed. Serum CK and blood gas analysis were normal (pH 7.398). Although blood levels of lactate and pyruvate were almost within normal limit, lactate was elevated by 20WATT-15 minutes exercises. On the contrary, the CSF levels of lactate and pyruvate were elevated markedly. CT of the brain revealed the presence of the low density areas in the right occipital and the left frontal lobes. Cranial 4 vessels studies were unremarkable. EEG showed the diffuse slowness with spike and wave complex. CT of the muscles were normal. A specimen obtained from the left biceps brachii muscle showed ragged-red fibers without obvious myogenic or neurogenic changes, and accumulations of abnormal mitochondria with paracrystalline inclusion bodies were observed by electron microscopy. However, mitochondrial abnormalities were not seen in the vessel walls in the biopsied muscle. Activities of complex I + III, II + III, IV in mitochondria were normal. Clinical features of this case were consistent with MELAS. However, this case showed no muscle weakness, short stature and lactic acidosis which characterize MELAS, and the onset of this case was later than those cases that were reported before.     

ATP, phosphocreatine and lactate in exercising muscle in mitochondrial disease and McArdle's disease

We studied exercise-induced changes in the adenosine triphosphate (ATP), phosphocreatine (PCr), and lactate levels in the skeletal muscle of mitochondrial patients and patients with McArdle's disease. Needle muscle biopsy specimens for biochemical measurement were obtained before and immediately after maximal short-term bicycle exercise test from 12 patients suffering from autosomal dominant and recessive forms of progressive external ophthalmoplegia and multiple deletions of mitochondrial DNA (adPEO, arPEO, respectively), five patients with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) 3243 A-->G point mutation, and four patients with McArdle's disease. Muscle ATP and PCr levels at rest or after exercise did not differ significantly from those of the controls in any patient group. In patients with mitochondrial disease, muscle lactate tended to be lower at rest and increase more during exercise than in controls, the most remarkable rise being measured in patients with adPEO with generalized muscle symptoms and in patients with MELAS point mutation. In McArdle patients, the muscle lactate level decreased during exercise. No correlation was found between the muscle ATP and PCr levels and the respiratory chain enzyme activity.     

A case with MELAS associated with epilepsia partialis continua

We report a 14-year-old boy with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS) who presented repeated episodes of abdominal pain and vomiting since the age of 8 years. In addition, he developed strokelike episodes with myoclonic seizures and transient hemiplegia on three occasions. At the age of 14-1/12-years, he also developed epilepsia partialis continua persisting for 10 days, which was associated with myoclonic seizures synchronized with spike discharges at the right central area. Laboratory examination disclosed increased levels of lactate and pyruvate in serum and CSF and low density areas in the bilateral temporal regions on CT scan. Muscle biopsy showed scattered ragged-red fibers. The enzyme activities (pyruvate dehydrogenase complex, pyruvate carboxylase, phosphoenol pyruvate carboxykinase, and cytochrome c oxidase) and the rates of decarboxylation of [3-14C]pyruvate in cultured skin fibroblasts were within normal ranges.     

Hypothalamic GH Deficiency and gelastic seizures in a 10-year-old girl with MELAS

A case of mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes, in which a pituitary growth hormone (GH) secretion deficiency of hypothalamic origin was revealed through neuro-endocrinological examinations, was described. The case was a 10-year-old girl, who had been suffering from generalized tonic seizures since age 5, four episodes of alternating hemiplegia since age 6, stunted growth since age 7, and simple partial motor seizures as well as gelastic seizures since age 8. Marked elevation of lactate and pyruvate in both serum and CSF, abundant ragged red fibers in biopsied muscle, and low density areas in the left occipital lobe and bilateral globus pallidus in addition to diffuse brain atrophy on CT scan and MRI of the head were demonstrated, although the activities of muscle enzymes complex I-IV were within normal ranges. Pituitary GH secretion was deficient under the loadings with insulin, L-DOPA, sleep, and a single growth hormone releasing factor (GRF) administration, but normal GH response was registered under the repetitive stimulation with GRF. Activities of other hormonal axes were normal. It is likely that short stature commonly observed in MELAS patients is due to hypothalamic dysfunction, which might be brought out by chronic ischemia and energy deficiency of the diencephalon based upon mitochondrial abnormality of that region. It is likely that gelastic seizure in this case is due to hypothalamic dysfunction.     

线粒体脑肌病伴有高乳酸血症和卒中样发作综合征的临床及基因突变分析

目的 探讨线粒体脑肌病伴有高乳酸血症和卒中样发作综合征(MELAS)的临床及基因突变特征. 方法 对1例MELAS患者的临床表现、影像学、肌肉病理特点进行分析,并用PCR-RFLP结合基因测序方法进行线粒体基因突变分析. 结果 患者主要临床表现为发作性头痛和呕吐、反复卒中样发作、癫痫、运动不耐受、身材矮小、神经性耳聋、乳酸水平升高等.脑CT见双侧基底节多个钙化灶,MRI见枕叶异常信号,1H-MRS见T2WI异常信号区域有明显的乳酸峰,在T2正常信号区域也有小的乳酸峰.光镜及电镜肌肉病理检查未见明显的线粒体异常,基因检测显示mtDNA A3243G杂合突变. 结论 MELAS的诊断必须结合临床表现、影像学、病理学和基因突变检测等结果进行综合分析,病理学检查阴性不能否定MELAS的诊断,诊断MELAS应常规进行mtDNA突变分析.     

MELAS without Ragged Red Fibers or Lactic Acidosis Diagnosed by Mitochondrial DNA Testing

Abstract: A case of mitochondrial encephalomyopathy with lactic acidosis, a stroke-like episode (MELAS) without ragged red fiber, diagnosed by mitochondrial DNA testing, is reported. A 37-year-old woman experienced a sudden and recurrent headache with vomiting and stroke-like episodes. Brain CT and MRI showed multiple infarction in the temporal lobes, not corresponding to artery distribution. However, the plasma levels of lactate and pyruvate were normal, and showed no increase after aerobic exercise. Biopsied muscle showed no evidence of ragged red fibers and deficient activity of mitochondrial enzymes in the respiratory chain. The final diagnosis was made by mitochondrial DNA testing. A southern blot analysis after Apa I digestion revealed the A-to-G mutation in the tRNA^{L eu (UUR)}, which is specific to MELAS.     

Hyperthyroidism associated with papilloedema and pyramidal tract involvement

Summary In a patient with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes [MELAS] who had normal mitochondrial enzyme activity, high doses of coenzyme Q₁₀ (CoQ) were administered. Clinical improvement with decreased serum lactate and pyruvate levels was observed. Though the mechanism of action of CoQ is not known, a trial is worthwhile in patients with MELAS.     

Melas: an original case and clinical criteria for diagnosis.

We describe the full history and postmortem findings in one of the first identified cases of mitochondrial encephalomyopathy with stroke-like episodes (MELAS). To clarify diagnostic criteria, we analyzed 69 reported cases. The syndrome should be suspected by the following three invariant criteria: (1) stroke-like episode before age 40 yr; (2) encephalopathy characterized by seizures, dementia, or both; and (3) lactic acidosis, ragged-red fibers (RRF), or both. The diagnosis may be considered secure if there are also at least two of the following: normal early development, recurrent headache, or recurrent vomiting. There are incomplete syndromes in relatives of patients with the full syndrome and incomplete syndromes might also be encountered in sporadic cases. Some MELAS patients have features of the Kearns-Sayre syndrome (KSS) or myoclonic epilepsy with ragged-red fibers (MERRF), but none had the full KSS syndrome. In partial or confusing cases, analysis of mitochondrial DNA (mtDNA) may point to the correct diagnosis; however, not all patients with clinical MELAS have had the typical mtDNA point mutation and some patients with the mutation have clinical syndromes other than MELAS.     

MELAS型线粒体脑肌病的临床、病理及影像学研究

目的：探讨线粒体脑肌病中ELAS型的临床、影像学、组织病理学特点及 诊断方法。方法：对4例MELAS患者的临床、影像学（CT、MRI）及组织商理学特点进行系统分析,观察3例患者的肌活检及2例患者的脑活检结果。结果：患者主要临床表现为运动不耐受、发作性头痛和呕吐,局灶或全身性癫痫,认知障碍,脑卒中样发作,神经性耳聋、肥厚性心肌病、内分泌功能紊乱,乳酸水平升高及身材矮小等,肌电图示肌源性改变,脑CT及MRI示病灶多位于枕、顶、颞叶脑回处、CT可见基底节及小脑钙化,肌肉组织可见不整红边纤维（RRF）和异常线粒体,脑活检灰质呈分层性坏死,小血管弥漫增生、星形胶质细胞增生及钙沉积,符合MELAS型诊断,结论：根据MELAS的临床及影像学特点,并结合肌肉及脑组织活检可对该病进行早期诊断。     

线粒体脑肌病伴高乳酸血症和卒中样发作综合征的影像学特征及动态演变

目的探讨线粒体脑肌病伴高乳酸血症和卒中样发作(MELAS)综合征的影像学特点及其动态演变过程。方法收集2011年1月-2016年2月我院经肌肉病理确诊的21例MELAS综合征的资料,对他们的头部CT、MRI、增强MRI、MRA和MRS表现进行回顾性分析。结果 19例患者行头部CT,其中8例显示双侧基底节区对称性钙化。卒中样发作急性期头部磁共振主要表现为T_1WI低信号、T_2WI和FLAIR高信号,DWI高信号或等信号,ADC高信号或低信号;增强MRI未见明显强化或线状强化,MRA未见明显异常,MRS可见N-乙酰天门冬氨酸峰(NAA)下降、乳酸峰(Lac)明显升高。19例(90.5%)病灶累及2个及2个以上脑叶,最常累及的部位是枕叶、颞叶和顶叶。病灶呈层状坏死,分布不符合脑血管的支配区域,动态观察具有"可逆性"、"游走性"和"进展性"。结论 MELAS综合征临床表现复杂,神经影像学具有一定的特征性,具有重要诊断价值。充分认识这些特征,有助于早期诊治、减少误诊。     

以乳酸血症和脑卒中样发作为主要临床表现的线粒体脑肌病

目的：报告线粒体脑肌病伴高乳酸血症和腩卒中样发作（MELAS）病1例,进行相关文献复习并探讨其临床表现、影像学和组织病理学特征。方法：对线粒体脑肌病MELAS患者的临床表现、影像学、组织病理学、免疫组化结果、辅助检查等情况进行分析,同时参考国内外文献对该病的报道。结果：MELAS的主要临床表现为发作性头痛和呕吐、全身性癫痫、精神障碍、脑卒中样发作、血乳酸增高;肌电图示神经源性改变;脑MRI示病灶多位于顶、枕、颞脑回处;肌肉活检见破碎样红纤维和异常线粒体,符合线粒体脑肌病MELAS的特征。结论：线粒体脑肌病MELAS的诊断主要根据临床表现和影像学特点,肌肉活检可确诊。     

An autopsy case of generalized seizures, myoclonus, blindness and deafness

We have reported the clinical and autopsy findings in a case with generalized seizures, myoclonus, blindness and deafness which was accompanied by stroke-like episodes. This case was diagnosed as mitochondrial encephalomyopathy, lactic acidosis & stroke-like episodes (MELAS) from these findings. Solitary and continuous lesions of softening were distributed in both hemispheres, more severely in the frontal and occipital poles. These lesions did not correspond to a vascular supply. The pulvinar, lateral and medial geniculate body of the thalamus, cerebellar vermis and dentate nucleus had small lesions of softening. The cortical lesions occurred mainly in layer 4, and the most prominent lesions among them appeared cystic, involving the subcortical white matter, but nerve cells in layer 1 and 2 were preserved. Proliferation of small blood vessels was seen around the softening areas. Electron microscopy revealed increased mitochondria in endothelial cells of these vessels, abnormal dense bodies in skeletal muscle cells and tightly packed mitochondria in choroid plexus epithelial cells. Immunohistochemical study suggested that vimentin positive cells were seen around lesions and proliferated vessels are different from those seen in the intact tissues.     

A study of familial MELAS: evaluation of A3243G mutation, clinical phenotype, and magnetic resonance spectroscopy-monitored progression

The clinical manifestations of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes syndrome (MELAS syndrome) are nonspecific and can easily be misdiagnosed. Magnetic resonance spectroscopy (MRS)-based detection of lactate in the brain has been found to be of diagnostic help in MELAS syndrome, however, the issue of whether MRS features vary by stage remains unresolved. We assessed the causative mutation and radiological features of a family of MELAS. Four of the family members harbored the A3243G mutation, probably of maternal inheritance. However, the clinical phenotypic expression was different in these patients. MRS showed a lactate peak, decreased N-acetylaspartate, choline, and creatine, which became more pronounced with progression of the disease, demonstrating that brain-MRS-based detection of lactate may be a suitable way to monitor the progression and treatment of MELAS.