Muscle fiber degradation in distal myopathy with rimmed vacuoles

Late-onset distal myopathy showed numerous rimmed vacuoles with the same properties as autophagic vacuoles. Electron microscopy showed numerous degenerated mitochondria, glycogen, or cell membranes in rimmed vacuoles, but no evidence that these vacuoles engulfed and contained intact or partially disrupted myofibrils. Immunostaining for myosin, -actinin, and actin, however, was sometimes positive within the vacuoles. Compared to the control muscle, there was increased staining activity by calpain around the rimmed vacuoles or in the cytoplasm of mainly atrophic fibers. The result seems to indicate an increase of calpain activity in these muscle fibers. We hypothesize that the myofibrils as well as mitochondria, glycogen, or cell membranes in this myopathy are degraded finally through a lysosomal autophagic process. However, the breakdown of the myofibrils may be not initiated by lysosomal activation; rather it may be the result of extralysosomal processes such as the calpain system.Supported by Research Grant 2A-1-10 for Nervous and Mental Disorders from the Ministry of Health and Welfare and by a Grant-in-Aid (04670493) for Scientific Research from the Ministry of Education, Science and Culture of Japan     

Muscle fiber degeneration in distal myopathy with rimmed vacuole formation

In 11 patients with distal myopathy with rimmed vacuole formation (DMRV), a well-known autosomal recessively inherited disorder, the rimmed vacuole formation appears to be the main pathological change accounting for the progressive muscle fiber degeneration. To gain a better understanding of the pathophysiology of the vacuole formation, we applied Congo red and immunohistochemical stains to muscle biopsies from these patients and the results were compared with those of patients with inclusion body myositis (IBM). The vacuoles in DMRV contained Congophilic amyloid material and deposits immunoreactive for -amyloid protein, both the NH₂ and COOH termini of -amyloid protein precursor, ubiquitin, and tau protein. These results were similar to those seen in our present cases of IBM as well as in previously reported cases. Therefore, there may be no pathogenetic differences in the formation of rimmed vacuoles in DMRV and IBM. Nevertheless, the degenerative process involved in rimmed vacuole formation in various diseases may share a common pathogenetic mechanism with that in amyloid-plaque formation in Alzheimer's disease brain as has been proposed previously.     

Tubulomembranous and fingerprint-like inclusions in biopsied muscle of distal myopathy with rimmed vascuoles

Summary Muscle biopsies from four patients were studied histochemically and electron-microscopically: they had myopathy of juvenile or early-adult onset, in which distal limb muscles were most severely affected but muscles supplied by cranial nerves were spared. Common histochemical findings included variation in fiber size, necrosis, phagocytosis, fiber splitting, central nuclei, endomysial fibrosis, and particularly rimmed vacuoles. Electron-microscopic examination revealed frequent autophagic vacuoles with numerous myeloid bodies. In addition, sarcoplasmic inclusion bodies with periodically laminated structures similar to the tubulomembranous structures (TMSs) first described by Fukuhara et al. (1981) in an atypical myopathy were found in all four cases, and in one, there were fingerprint-like structures resembling those described in neuronal ceroid-lipofuscinoses. These inclusions occasionally contained areas resembling lipofuscin pigment. They are certainly residual bodies of lysosomal origin, which might be related to the rimmed-vacuolar degeneration of the muscle, but whether or not they represent some specific metabolic abnormalities seems to remain an open question since the present cases differed clinically from either of the atypical myopathies with TMSs (Fukuhara et al. 1981) or any type of neuronal ceroid-lipofuscinosis.Supported by grants no. 81-08-20 and no. 82-04-32 from the National Center for Nervous, Mental, and Muscular Disorders (NCNMMD) of the Ministry of Health and Welfare, Japan     

Reducing bodies in distal myopathy with rimmed vacuole formation

A 42-year-old woman with distal myopathy with rimmed vacuoles had intracytoplasmic inclusion bodies similar to those described in reducing body myopathy. Since these inclusions were found in fibers with high acid phosphatase activity and occasional rimmed vacuoles, their formation appeared to correlate with active myofibrillar degeneration, but their origin remains unknown.     

Rimmed vacuolar distal myopathy

Summary An ultrastructural study of biopsied muscles was performed in seven patients with rimmed vacuolar distal myopathy, which was characterized by prominent rimmed vacuoles in the muscle fibers. The earliest changes noted were focal proliferation of the Golgi's apparatus and mitochondrial degeneration with myofibrillar loss. A proliferation of the T-system appeared later. Secondary lysosomes (autophagosomes) could be noted much later and gradually increased in number. Autophagosomes tended to coalesce and became larger autophagic vacuoles, which were surrounded in part by relatively preserved myofibrils and partly by a single membrane. Gently curved laminated structures (tubulomembranous structures) were seen in the degenerating muscle fibers and also in relatively intact fibers, satellite cells, and interstitial cells in all cases. They were closely associated with lipofuscin-like material. These findings suggest that an abnormality of the lysosomal system might be essential in the pathogenesis of rimmed vacuolar distal myopathy.     

Atypical Parkinsonism in distal myopathy with rimmed vacuoles

A patient with distal myopathy with rimmed vacuoles (DMRV) exhibited Parkinsonism with a severe writing tremor that responded poorly to levodopa. Molecular genetic analysis revealed that the patient had the D176V/V572L compound heterozygous mutation in the UDP‐N‐acetylglucosamine 2‐epimerase/N‐acetylmannosamine kinase (GNE) gene. Histopathological examination of a biopsied muscle specimen yielded findings compatible with those of DMRV, which is characterized by the presence of rimmed vacuoles without inflammatory cell infiltration in muscle fibers. The finding of normal cardiac meta‐iodobenzylguanide uptake makes the possibility of incidental Parkinson's disease in this patient unlikely. These observations raise the possibility that atypical Parkinsonism is a rare complication of DMRV associated with GNE mutation. © 2008 Movement Disorder Society     

Specific binding of Ulex europaeus agglutinin I lectin to sarcolemma of distal myopathy with rimmed vacuole formation

Ulex europaeus agglutinin I (UEA I) binding was studied in 83 patients with various neuromuscular disorders. UEA I labelled endomysial capillaries and endothelial cells of perimysial blood vessels in all the examined muscles. There was no UEA I binding to muscle fibres except for all (9) cases of distal myopathy with rimmed vacuole formation (DMRV), 1 of 5 cases of inclusion body myositis and 1 of 36 cases of inflammatory myopathies. The UEA I binding was completely eliminated by preincubation of UEA I solution with l-fucose. Using electron microscopy, the UEA I binding was localized to sarcolemma and intrasarcoplasmic membranous organelles other than mitochondria. Myosatellite cells were not labelled. These findings revealed the existence of fucosylated proteins or lipids in a subset of skeletal muscles suffering from DMRV. Biochemical identification of the fucosylated substance and further detailed study on subcellular localization of UEA I binding may yield important clues to the unknown pathogenesis of DMRV. Received: 23 January 1997 / Received in revised form: 8 April 1997 / Accepted: 11 June 1997     

Rimmed vacuolar distal myopathy: a clinical,electrophysiological, histopathological and computed tomographic study of seven cases

Summary The following report describes the clinical, laboratory, electrophysiological, histopathological and computed tomographic studies of seven cases of distal myopathy with rimmed vacuoles in the muscle fibers. Each displayed several characteristic features. First, the onset was in early adulthood. Second, there was a unique distribution of muscle involvement: tibialis anterior and extensor digitorum and hallucis muscles were initially and most severely affected. The hamstrings and adductors of the thigh were also markedly involved. The gluteus medius and minimus muscles and the neck flexors were mildly affected in the relatively early stages. In contrast, the gastrocnemius, soleus, quadriceps femoris, and gluteus maximus muscles were well preserved until an advanced stage. Third, serum creatine kinase activity was normal or only mildly elevated; fourth, EMG were mainly myopathic, with certain neuropathic features; and fifth, histopathologically rimmed vacuoles in muscle fibers were found associated with certain neuropathic features, such as angular fibers, clustering of atrophic fibers, pyknotic nuclear clumps, and fiber-type predominance. The characteristic distribution of skeletal muscle involvement was particularly noticeable, together with certain neuropathic features of the EMG and muscle biopsy in rimmed vacuolar distal myopathy.     

Rimmed vacuoles in biopsied muscle of nemaline myopathy

Summary A case of nemaline myopathy with rimmed vacuoles was presented. Muscle biopsy revealed type I fiber predominance with type grouping, thus suggesting that neurogenic factors played a pathologic role in the degenerative change.     

Late-onset distal myopathy with rimmed vacuoles without mutation in the GNE or dysferlin genes

We report two brothers from a Japanese family with a late-onset distal myopathy characterized by rimmed vacuoles and dysferlin deficiency with no inflammatory infiltration and dystrophic changes in muscle biopsy. Mutations in the GNE, dysferlin, caveolin 3, emerin, and lamin A/C genes were excluded. We speculate that dysferlin is involved in the pathogenesis of the myopathy in these patients, which may represent a new disease entity presenting as a distal myopathy.     

Myopathy with mitochondrial abnormalities and rimmed vacuoles

Summary A man of 44 years suffering from an exercise-induced neuromuscular disease with mitochondrial abnormalities and rimmed vacuoles is reported. The mitochondrial abnormalities and rimmed vacuoles (autophagic vacuoles) are interpreted as sequential changes of the same pathogenetic process depending on the degree of energy deficiency.     

DNA single-strand breaks are increased in muscle diseases with rimmed vacuoles

Some pathological similarities between Alzheimer’s disease and muscle diseases with rimmed vacuoles (RV) have been pointed out. For example, several pathological hallmark proteins have been reported to be immunopositive in the lesions of both diseases. Since apoptotic processes or primary DNA damage are suggested to play a role in the pathomechanism of Alzheimer’s disease, we examined DNA double-strand breaks (DSB) and single-strand breaks (SSB) in the muscle biopsy specimens of several diseases, including muscle diseases with RV. Although no DSB-positive myonuclei were detected in any muscles examined, the number of SSB-positive myonuclei markedly increased in the muscles from cases with polymyositis and muscle diseases with RV. In polymyositis, SSB-positive myonuclei were observed in regenerating fibers and muscle fibers in the vicinity of inflammatory infiltrates, suggesting that the increase of SSB is due to muscle fiber regeneration following necrosis and inflammation. In muscle diseases with RV, however, SSB-positive myonuclei were observed in small angulated fibers and in morphologically normal fibers, regardless of necrosis, regeneration or inflammation. These findings suggest that muscle diseases with RV may share a common pathological process involving DNA damage. Received: 30 August 1999 / Revised, accepted: 20 December 1999     

Distal myopathy with rimmed vacuoles: clinical and muscle morphological characteristics and spectrum of GNE gene mutations in 53 Chinese patients

Abstract

Objectives: Distal myopathy with rimmed vacuoles (DMRV) is a typical autosomal recessive hereditary inclusion body myopathy, characterized by slowly progressive distal muscle weakness with relative sparing of the quadriceps. This study aimed to investigate the variability of clinical and morphological presentation and the spectrum of Glucosamine (UDP-N-acetyl)-2-epimerase/N-acetylmannosamine kinase (GNE) mutations in Chinese DMRV patients.

Methods: We retrospectively reviewed the medical records of 37 patients with DMRV in PLA General Hospital from 1986 to 2011, and further conducted a review of 16 reported Chinese DMRV patients from other hospitals. We systematically analyzed the clinical, muscle morphological features and GNE gene mutation status of all DMRV patients.

Results: A total of 53 DMRV patients were studied. Fourteen cases had family history and other 39 cases were sporadic. Fifteen cases showed atypical pathological presentation as mononuclear cell invasion into necrotic or non-necrotic muscle fibers. Rare initial symptom, earlier age of onset and more dysmorphic presentations were shown in sporadic patients. Eighteen mutations in GNE gene were identified. c.317T>C (p.I106T) was a novel GNE gene mutation. c.1892C>T (p.A631V), c.527A>T (p.D176V) and c.1523T>C (p.L508S) were the common GNE mutations in Chinese DMRV patients.

Discussion: The clinical, pathological and genetic characteristics of DMRV are distinct in Chinese patients.     

Intranuclear and cytoplasmic filamentous inclusions in distal myopathy (Welander)

Summary Ultrastructural examination of anterior tibial muscle from four patients with late-onset autosomal dominant distal myopathy of Welander-type revealed intrasarcoplasmic filamentous inclusions in association with rimmed vacuoles. In one of the patients, identical intranuclear filamentous inclusions were also found. These filamentous inclusions are similar to those desxribed in inclusion body myositis (IBM). They have also been observed in hereditary neuromuscular disorders including autosomal recessive distal myopathy. Thus, the filamentous inclusions occur in different neuromuscular conditions with different etiologies. These findings further raise the question of the specificity of the filamentous inclusions in IBM.Supported by grants from the Swedish Medical Research Council (proj. 3875, visiting research grant K. Borg), the Swedish MS foundation, the Swedish Society of Medicine, the Swedish Society for Traffic and Polio Disabled, Erik and Edith Fernströms Foundation for Medical Research and from the Karolinska Institute     

Tau protein immunoreactivity in muscle fibers with rimmed vacuoles differs from that in regenerating muscle fibers

Summary To determine whether tau protein found in muscle fibers with rimmed vacuoles and in regenerating fibers was phosphorylated, we examined eight muscle biopsy samples containing rimmed vacuoles (from five patients with distal myopathy with rimmed vacuole formation and three patients with inclusion body myositis) and three muscle biopsy samples from patients with Duchenne muscular dystrophy containing numerous regenerating fibers. Although both rimmed vacuolated and regenerating fibers had increased immunoreactivity against tubulin and tau protein, tau protein in the former was more highly phosphorylated than that in the latter. While very few microtubules in muscle fibers with rimmed vacuoles were recognizable by electron microscopy, regenerating fibers, especially immature ones, contained numerous microtubules. Since tau protein found in vacuolated fibers is hyperphosphorylated, it can be considered to have reduced ability to bind tubulin molecules. Thus, the tau protein cannot stabilize microtubules, resulting in their depolymerization even in the presence of tubulin molecules.     

Molecular pathomechanism of distal myopathy with rimmed vacuoles]

Distal myopathy with rimmed vacuoles (DMRV) and hereditary inclusion body myopathy (HIBM) are genetically identical autosomal recessive muscle disorders caused by mutations in the GNE gene. This gene encodes a bifunctional protein with UDP-GlcNAc 2-epimerase and ManNAc kinase activities that catalyze the rate limiting step and the succeeding step, respectively, in the sialic acid biosynthetic pathway. V572L mutation is the most prevalent among Japanese DMRV patients and accounts for about 60% of mutant alleles. Clinical spectrum of DMRV/HIBM seems to be wider than previously thought in terms of both the severity of the disease and the range of affected organs. There are rare asymptomatic homozygotes with missense GNE mutations, indicating the presence of mitigating factors. Surprisingly, more than 10% of the patients had a variety of cardiac abnormalities, suggesting that skeletal muscle may not be the only organ involved. Studies on recombinant GNE demonstrate a loss-of-function nature of the missense mutations identified. Patients' cells show decreased sialylation status which can be recovered by adding GNE metabolites, such as ManNAc and NeuAc. This indicates the possibility of developing a therapy for DMRV/HIBM by giving these metabolites to patients although we have to await the model mice that are currently being produced at several laboratories.     

Nonaka肌病伴面部肌肉受累

目的 报道1个伴随面部肌肉受累及的Nonaka型远端性肌肉病家系的临床和病理特点，讨论其发病机制。方法 先证者在中年早期起病。主要临床表现为胫前肌为主的四肢远端肌无力和肌萎缩，伴随有面肌和胸锁乳突肌力弱以及眼睑下垂，股四头肌不受累。肌酶轻度升高。肌电图提示肌源性损害。对患者进行胫前肌活检，进行组织学，酶组织化学和超微结构检查。家族中其妹妹也具有相同的临床表现。出现下肢远端为主的肌无力和肌萎缩。结果 肌肉病理改变特点是出现肌纤维肥大和萎缩。伴随核内移和肌纤维分裂现象。在部分肌纤维内可见镶边空泡和胞浆体。电镜下可见肌纤维内和核内的管丝包涵体以及髓样小体，其中出现在膜下的管丝包涵体具有细胞核的轮廓，可以看到细胞核变性后形成致密破碎结构。结论 结合患者的家庭史，临床表现和病理学改变特点。此患者可以考虑为Nonaka肌病，我们证实此病可以伴随面部肌肉的受累及。其发病机制可能与肌核的变性有关。     

MRI findings in studies of distal myopathy with rimmed vacuoles

A case of distal myopathy with rimmed vacuoles was studied with MRI, which showed a characteristic distribution of the affected muscles. A 41-year-old man who presented a slowly progressive weakness in his lower legs starting 11 years previously was admitted to our hospital of further investigation. Neurological examinations showed muscular wasting and weakness in the neck flexors, the flexors of the forearm, the flexors and adductors of the thigh and the extensors of the lower legs. Needle electromyography showed a myopathic pattern. Muscle biopsy revealed a variation in fiber size, an increase in internal nuclei, fatty infiltration and scattered rimmed vacuoles in a histochemical study. Electron microscopy revealed that rimmed vacuoles contained numerous lamellar bodies and glycogen particles. T1 and T2 weighted MRI showed high signals in the m. adductor of thigh m. biceps femoris, m. semimembranosus, m. semitendinosus, m. tibialis anterior, m. tibialis posterior, m. extensor digitorum longus, m. extensor digitorum brevis, m. peroneus, and m. gastrocnemius. There were three merits for the application of MRI to distal myopathy, (1) easy detection of the affected muscles as fatty change is expressed with a high signal intensity by MRI, (2) no affection by the presence of bones in MRI, and (3) the possibility to have a transverse section and a sagittal and coronal section in MRI. In this case MRI was very useful to detect the affected muscles and to observe the progress.     

Mutation analysis of the GNE gene in distal myopathy with rimmed vacuoles (DMRV) patients in Thailand

Distal myopathy with rimmed vacuoles (DMRV) is an early-adult-onset, distal myopathy caused by a mutation of the UDP-N-acetylglucosamine 2 epimerase/N-acetylmannosamine kinase (GNE) gene. We herein report four Thai patients with DMRV who carried compound heterozygous mutations of the GNE gene including three novel (p.G89R, p.P511T, and p.I656N) and two known mutations (p.A524V and p.V696M). All patients shared p.V696M in one allele. Our study demonstrates the mutation spectrum of the GNE gene in Thai patients with DMRV.