Distal muscular dystrophy of the Miyoshi type

OBJECTIVE: Miyoshi myopathy is an autosomal recessive muscular dystrophy. It is characterized by distal muscle involvement, especially the gastrocnemius and soleus. The disease starts with weakness and atrophy of the calves. MATERIAL AND METHODS: Here we report on 2 patients, brother and sister, from a Turkish family. Onset of the disease was at the age of 20 and 26 years of age, respectively. In both siblings, there was an early and predominant involvement of the distal muscles of the lower limbs. Creatine kinase activity was elevated 50- to 100-fold above normal values. RESULTS: Electromyography revealed a myopathic pattern. Histology of the biceps muscles indicated some myopathic changes consistent with muscular dystrophy. Occurrence in only these 2 siblings with no other family members was indicative of an autosomal recessive inheritance. CONCLUSIONS: We describe the distinctive clinical features in 2 siblings of a Turkish family with MM as differential diagnosis and histological change.     

Hereditary inclusion-body myopathy associated with cardiomyopathy: report of two siblings

Hereditary inclusion-body myopathy (HIBM) or distal myopathy with rimmed vacuoles (DMRV) is an autosomal recessive disorder characterized by preferential involvement of distal muscles in the lower extremities, especially the anterior compartment of the legs, with relative preservation of the quadriceps.This is referred to as quadriceps-sparing myopathy. Previous reports have revealed exclusive involvement in skeletal muscles. Herein we describe two siblings with typical HIBM/DMRV. The patients developed exertional dyspnea 20-26 years after disease onset. Echocardiogram revealed a cardiomyopathy in both patients. This is the first report of the association between HIBM/DMRV and cardiomyopathy.     

Axial myopathy – an unrecognised entity

Axial myopathy (AM) is a rare neuromuscular disorder characterised by selective involvement of the spinal muscles with a bent spine and/or drooping head as leading clinical features. We here report the results of clinical, histopathological, MRI, molecular genetics and electrophysiological investigations carried out on six patients affected by pure axial myopathy. Symptoms appeared within an age range of 35 to 56 years. The first symptoms were difficulty in keeping the trunk and head in an upright position. Both bent spine and dropped head were reduced in a supine position. The disease was slowly progressive. Muscle strength examination and muscle imaging revealed involvement of the spinal and neck extensor muscles only. Serum CK was normal to slightly increased. EMG and muscle biopsy specimens obtained from spinal muscles showed an advanced chronic myopathic pattern. We conclude that axial myopathy may be much more common than previously thought, because gradual progression of cervical kyphosis may often be explained as a feature of normal ageing or as an associated sign of several neurological disorders and vertebral degeneration diseases. Received: 24 June 2001, Received in revised form: 2 November 2001, Accepted: 6 November 2001     

Early onset distal muscular dystrophy with normal dysferlin expression

A 7-year-old boy, who was noted to be a slow runner at the age of 2 years, had progressive muscle weakness and atrophy, preferentially affecting distal muscles. At 3 years of age, he had scoliosis and difficulty in standing on tip-toe. Serum creatine kinase was 1074 IU/l. Muscle CT scan showed low-density areas in the lower legs and upper arms, but predominantly in the gastrocnemius and soleus muscles. Biopsy of the biceps brachii muscle showed moderate dystrophic changes with normal dysferlin expression on immunohistochemical and western blot analyses. Although muscle involvement mimicked that seen in Miyoshi myopathy (MM), the very early onset of the disease and scoliosis were quite unusual for MM. We, therefore, made the diagnosis of early onset dysferlin-positive distal muscular dystrophy, probably a new type of distal muscular dystrophy.     

Muscle magnetic resonance imaging shows distinct diagnostic patterns in Welander and tibial muscular dystrophy

OBJECTIVES: This is a report on a retrospective muscle magnetic resonance imaging (MRI) study on 11 patients affected by Welander distal myopathy (WDM) and 22 patients with tibial muscular dystrophy (TMD) carried out in order to define the pattern and characteristics of muscle involvement. RESULTS: WDM patients showed involvement of gastrocnemius, soleus, tibial anterior (TA) and extensor digitorum longus (EDL), as well as hamstrings and hip adductor muscles. TMD patients showed involvement of the TA and EDL muscles, and in some patients also hamstring and posterior compartment muscles of the legs. Some patients showed asymmetry of muscle involvement. CONCLUSION: We conclude that muscle MRI examination proved to be very useful in the determination of the exact pattern of muscle involvement in WDM and TMD. Clinical testing using the Medical Research Council scale is not sensitive enough to establish the pattern of muscle involvement in focal muscle diseases.     

Late-onset mitochondrial myopathy with dystrophic changes due to a G7497A mutation in the mitochondrial tRNASer (UCN) gene

Mutations of mitochondrial tRNA genes are usually associated with multi-systemic disorders with onset of symptoms in childhood or early adulthood. Dystrophic myopathic changes are not typical features of these disorders. We report two siblings with a severe progressive myopathy of late onset without external ophthalmoplegia and without involvement of the central and peripheral nervous system. Muscle biopsy specimens showed severe myopathic changes similar to those found in muscular dystrophies. Molecular analysis revealed a G7497A mutation in the mitochondrial tRNA^Ser(UCN) gene. In both patients, the proportion of mutated mitochondrial DNA in muscle was more than 97%. Mitochondrial disorder associated with the G7497A mutation has to be included into the differential diagnosis of severe progressive late-onset myopathy with histopathological dystrophic myopathic changes. Mitochondrial myopathy and high level of mutated mtDNA might be a characteristic of the G7497A tRNA^Ser(UCN) mutation.     

A novel compound heterozygous dysferlin mutation in Miyoshi myopathy siblings responding to dantrolene

Miyoshi myopathy (MM) is an autosomal recessive distal muscular dystrophy characterized by mutations of the dysferlin gene. Although several pairs of homozygous/heterozygous mutations have been reported, few effective treatments of MM are available. We had observed the decreased serum creatine kinase (CK) before and after administration of dantrolene in the elder brother and the increased serum CK before and after discontinuance of the drug on suspicion of drug-induced hepatopathy in the younger sister. We report a novel pair of heterozygous mutations in the 3'-splicing site of exon 26 and the translation site of exon 28 of the dysferlin gene in two siblings, and effective treatment of their MM with dantrolene.     

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.     

Distinct distal myopathy phenotype caused by VCP gene mutation in a Finnish family

Inclusion body myopathy with Paget disease and frontotemporal dementia (IBMPFD) is caused by mutations in the valosin-containing protein (VCP) gene. We report a new distal phenotype caused by VCP gene mutation in a Finnish family with nine affected members in three generations. Patients had onset of distal leg muscle weakness and atrophy in the anterior compartment muscles after age 35, which caused a foot drop at age 50. None of the siblings had scapular winging, proximal myopathy, cardiomyopathy or respiratory problems during long-term follow-up. Three distal myopathy patients developed rapidly progressive dementia, became bedridden and died of cachexia and pneumonia and VCP gene mutation P137L (c.410C > T) was then identified in the family. Late onset autosomal dominant distal myopathy with rimmed vacuolar muscle pathology was not sufficient for exact diagnosis in this family until late-occurring dementia provided the clue for molecular diagnosis. VCP needs to be considered in the differential diagnostic work-up in patients with distal myopathy phenotype.     

Atypical presentation of GNE myopathy with asymmetric hand weakness

GNE myopathy is a rare autosomal recessive muscle disease caused by mutations in GNE, the gene encoding the rate-limiting enzyme in sialic acid biosynthesis. GNE myopathy usually manifests in early adulthood with distal myopathy that progresses slowly and symmetrically, first involving distal muscles of the lower extremities, followed by proximal muscles with relative sparing of the quadriceps. Upper extremities are typically affected later in the disease. We report a patient with GNE myopathy who presented with asymmetric hand weakness. He had considerably decreased left grip strength, atrophy of the left anterior forearm and fibro-fatty tissue replacement of left forearm flexor muscles on T1-weighted magnetic resonance imaging. The patient was an endoscopist and thus the asymmetric hand involvement may be associated with left hand overuse in daily repetitive pinching and gripping movements, highlighting the possible impact of environmental factors on the progression of genetic muscle conditions.     

Autosomal dominant distal myopathy with desmin storage: A clinicopathologic and electrophysiologic study of a large kinship

A large family is described with an autosomal dominant distal myopathy, the nature of which prompts the reevaluation of current classifications of these disorders. The disease begins in early to middle adulthood with gait disturbance due to distal leg weakness, and progresses over 5–10 years to involve all extremities, as well as bulbar, respiratory, and facial muscles. There is frequent cardiac involvement, manifest by arrhythmias, conduction blocks, and congestive failure, resulting in premature demise. On electromyography there is prominent spontaneous activity, short duration motor unit potentials, and polyphasia. Muscle biopsies from multiple family members at different stages of the disease are characterized by desmin storage and autophagocytosis. This distal myopathy differs from other phenotypically similar disorders in its rapidity of progression, fatal course and pathologic features. The role and specificity of excessive desmin accumulation in this and other myopathic and cardiac disorders are unknown. © 1994 John Wiley & Sons, Inc.     

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。     

A 78-year-old Japanese male with late-onset PHKA1-associated distal myopathy: Case report and literature review

PHKA1 mutations are causative for glycogen storage disease type IXd (GSDIXd), a myopathy that can be asymptomatic or associated with exercise intolerance, and rarely is accompanied by weakness or atrophy of limbs. Here we report a patient with GSDIXd who developed distal myopathy which was not accompanied by exercise intolerance at age 71. Muscle MRI revealed severe but gradual involvement of muscles with disease progression in the order of medial gastrocnemius, soleus, lateral gastrocnemius, and gluteus muscles. Muscle pathology revealed vacuolar changes with glycogen accumulation, and muscle enzymatic activity of phosphorylase b kinase was markedly decreased to 1.5 nmol of substrate utilized/min/mg protein (normal range: 39.5 ± 10.8). Collectively, the present findings suggest that PHKA1-associated distal myopathy is an adult-onset distal calf dominant myopathy which does not always present with exercise intolerance.     

Novel dysferlin mutations and characteristic muscle atrophy in late-onset Miyoshi myopathy

Miyoshi myopathy is characterized by weakness of the calf muscles during early adulthood. We report a case of late-onset Miyoshi myopathy presenting at 48 years of age, with novel mutations in the dysferlin gene. Muscle computed tomography clearly revealed severe atrophy in the soleus and medial gastrocnemius muscles. Even older patients with atrophy in the posterior compartment of the distal lower extremities and a relatively high serum creatine kinase level should be examined for the dysferlin gene.     

ZASP基因突变所致肌原纤维病一家系报道及文献复习

目的通过对ZASP基因突变所致肌原纤维病一家系报道及文献复习,了解该病的临床、病理及基因突变特点。方法分析1例远端肌病患者的临床、肌肉MRI及肌肉病理特点,并追踪其家系家族史。先证者外周血提取DNA,进行目标区序列捕获二代测序(含58个肌病相关基因),明确存在ZASP基因变异。对家系其他成员进行Sanger测序进一步明确及验证突变位点。结果先证者为中年女性,52岁起病,表现为进行性双下肢无力伴双腿变细。先证者家系2代15名中,除先证者外共6名存在肌肉受累,4名为先证者同代亲属,临床特点与先证者类似;2名为先证者下一代亲属,其中1名仅有闭目肌受累及肌酸激酶(CK)轻度升高(291 U·L-1),另1名仅有CK轻度升高(199 U·L-1)。先证者肌肉病理发现肌细胞内有异常嗜伊红物质沉积和镶边空泡形成,免疫组化染色可见肌纤维内desmin蛋白沉积。电镜下可见Z线附近致密颗粒沉积。目标区序列捕获二代测序及Sanger测序确定该家系致病基因为ZASP基因已报道错义突变p.A147T(c.G439A)。结论 ZASP基因突变所致的肌原纤维病家系为国内首次报道。     

Variable reduction of caveolin-3 in patients with LGMD2B/MM

Abstract. Mutations in the human dysferlin gene (DYSF) cause autosomal recessive muscular dystrophies characterized by degeneration and weakness of proximal and/or distal muscles: limb girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy (MM). Recently, an interaction between caveolin-3 and dysferlin in normal and dystrophic muscle (primary caveolin-3 deficiency; LGMD1C) was shown. In this study, clinical,morphological and genetic analysis was carried out in four independent LGMD2B/MM patients. All patients presented with an adult-onset, slowly progressive muscular dystrophy with variable involvement of proximal and distal muscles. We found complete lack of dysferlin in the four LGMD2B/MM patients. Secondary reduction of caveolin-3 was detected in three out of the four patients. Regular caveolae were detected along the basal lamina in two patients by electron microscopy. We provide further evidence that dysferlin and caveolin-3 interact in human skeletal muscle. It remains to be elucidated whether the loss of this interaction contributes to pathogenic events in muscular dystrophy.M. C. Walter and C. Braun contributed equally.     

Muscle-nerve involvement in autosomal dominant progressive external ophthalmoplegia with hypogonadism

Sixteen members of a family with a history of autosomal dominant progressive external ophthalmoplegia (adPEO) with hypogonadism were examined. The muscular involvement commenced cranially and descended in relation to increasing disease duration. The neuromuscular signs were PEO, dysarthria, dysphonia, limb muscle weakness with wasting, absence of Achilles tendon reflexes, and distal vibration sensory loss. The electromyogram (EMG) was myopathic in facial and proximal limb muscles. Neurogenic involvement was suspected in a few tibial anterior muscles. Neurography showed signs of axonal neuropathy correlated to clinical signs. F-responses were reduced in number or absent in peroneal nerves, and did not correlate to clinical signs or disease duration. Muscle biopsies in advanced cases had structural abnormalities of mitochondria, ragged-red fibers, and focal cytochrome c oxidase deficiency. A combination of muscle-nerve involvement with PEO, Achilles tendon areflexia, distal vibration sensory impairment, myopathic EMG, and abnormally low sural nerve responses seems to be typical of this type of mitochondrial disorder. © 1996 John Wiley & Sons, Inc.     

Dysferlin肌病的临床和病理特点分析(附6例报道)

目的:探讨dysferlin肌病的临床和病理特点。方法:对9例患者的肌肉病理标本进行组织化学和免疫组化染色检查,并对肌肉组织进一步行dysferlin蛋白的Westernblot分析。结果:9例患者中确诊6例为dysferlin肌病,病理表现均为肌源性损害,无边缘空泡,其中2例患者的病理分析有炎细胞浸润。根据临床表现特点,6例患者中有3例为Miyoshi肌病(MM),2例为肢带型肌营养不良2B型(LGMD2B),1例为远端前群肌病(DACM)。结论:Dysferlin肌病在肌电图上为肌源性损害、肌酶显著升高,其临床表现多样,dysferlin免疫组化染色联合Westernblot有着重要诊断意义。     

Autophagic vacuolar myopathy involving the phenotype of spinocerebellar ataxia type 3

Spinocerebellar ataxia type 3 (SCA3) is a form of autosomal dominant cerebellar ataxia with a wide range of clinical manifestations, including ataxia and pyramidal and extrapyramidal signs. A few SCA3 patients have been noticed to be predisposed to the development of inclusion body myositis. It is still unknown whether muscle can be primarily involved in the pathogenesis of SCA3. This study reported an SCA3 family in which the index patient initially presented with parkinsonism, sensory ataxia, and distal myopathy but the absence of cerebellar and pyramidal symptoms. The clinical and electrophysiological studies implied a possible combination of distal myopathy and sensory–motor neuropathy or neuronopathy. MRI muscle showed selective fat infiltration and absence of denervated edema-like changes, indicating the distal muscle weakness had a myopathic origin. Muscle pathology showed the myopathic involvement, besides neurogenic involvement, characterized by chronic myopathic changes with multiple autophagic vacuoles. Genetic screening revealed expanded CAG of 61 repeats in the ATXN3 gene, which showed co-segregation in the family. Besides the neurogenic origin, the myopathic origin may be partly attributed to the limb weakness of SCA3 patients, which expands the spectrum of the clinical manifestation of SCA3.     

Myopathy in two siblings with nephropathic cystinosis

Nephropathic cystinosis is a hereditary disorder characterized by a specific defect in the transport of cystine across the lysosomal membrane leading to an accumulation of protein-free cystine in tissues including conjuctiva liver bone marrow and kidney. Renal transplantation is necessary because of renal failure. With improved life-expectancy neurological complications have been reported including cases of distal myopathy diagnosed ante-and post mortem. We report on two further rare cases of two siblings suffering from cystinosis who developed a predominantly distal myopathy proven electrophysiologically and on biopsy during life. The reported clinical picture of a distal atrophy resembling a neurogenic disease confirms a picture apparently typical in cystinosis. Possible effects of cysteamine therapy on the course of the myopathy are discussed.