Extra-muscular manifestations in GNE myopathy patients: A nationwide repository questionnaire survey in Japan.

OBJECTIVE: GNE myopathy is a rare autosomal recessive adult-onset distal myopathy caused by biallelic pathogenic variants in GNE. Although some extra-muscular manifestations associated with GNE myopathy have been reported, little is known about whether they are disease-specific and how often they present. This study aimed to characterize extra-muscular manifestations of GNE myopathy. METHODS: We conducted a questionnaire survey of GNE myopathy patients registered in a national registry in Japan. The questionnaire requested information regarding idiopathic thrombocytopenia, cardiac involvement, respiratory involvement, sleep apnea syndrome (SAS), and psychiatric diseases. RESULTS: The response rate was 62.4% (126/198), yielding a total of 51 male and 75 female participants. Of the participants, 4.1% (5/123) had a diagnosis of idiopathic thrombocytopenia, and 16.3% (8/49) of males and 6.6% of females (5/76) had a diagnosis of SAS. In total, 0.8% (1/126) of participants had pervasive developmental disabilities and 14.7% (16/109) had a psychiatric disease. CONCLUSION: The frequencies of idiopathic thrombocytopenia and SAS among Japanese GNE myopathy patients were higher than those observed in the general Japanese population. Routine blood tests and evaluation of sleep-disordered breathing should be considered in order to better manage GNE myopathy patients.

Subclinical Cardiomyopathy in Miyoshi Myopathy Detected by Late Gadolinium Enhancement Cardiac Magnetic Resonance Imaging.

Dysferlin is a sarcolemmal protein present in muscle cells. It is responsible for muscle membrane repair. Dysferlin gene (DYSF) mutation, resulting in deficiency in this protein, is termed dysferlinopathy. Clinically, it manifests as early adulthood onset of muscle weakness with markedly elevated creatine kinase levels. The main phenotypes are limb-girdle muscular dystrophy type 2B (LGMD2B), affecting proximal muscles, and Miyoshi myopathy (MM), affecting distal muscles. Dysferlin is also present in cardiomyocytes, and case reports have emerged of cardiac abnormalities in dysferlinopathy. While routine methods of cardiac screening, namely, electrocardiography or echocardiography, are convenient and noninvasive, they often exhibit insufficient diagnostic sensitivity for detecting subclinical cardiac remodeling during early stages of cardiomyopathy. Cardiac magnetic resonance imaging though can provide accurate assessment of cardiac chamber sizes and function. With gadolinium administration, it can also detect areas of myocardial scarring and fibrosis. Early diagnosis of neuromuscular disease-related cardiomyopathy is of clinical significance, as appropriate treatment can retard myocardial fibrosis, delaying cardiomyopathy progression. We present a case of a patient with MM incidentally diagnosed with concomitant cardiomyopathy.

ASAH1-related disorders: Description of 15 novel pediatric patients and expansion of the clinical phenotype.

Acid ceramidase deficiency is an orphan lysosomal disorder caused by ASAH1 pathogenic variants and presenting with either Farber disease or spinal muscle atrophy with progressive myoclonic epilepsy (SMA-PME). Phenotypic and genotypic features are rarely explored beyond the scope of case reports. Furthermore, the new biomarker C26-Ceramide requires validation in a clinical setting. We evaluated the clinical, biomarker and genetic spectrum of 15 Egyptian children from 14 unrelated families with biallelic pathogenic variants in ASAH1 (12 Farber and 3 SMA-PME). Recruited children were nine females/six males ranging in age at diagnosis from 13 to 118 months. We detected ASAH1 pathogenic variants in all 30 alleles including three novel variants (c.1126A>G (p.Thr376Ala), c.1205G>A (p.Arg402Gln), exon-5-deletion). Both total C26-Ceramide and its trans- isomer showed 100% sensitivity for the detection of ASAH1-related disorders in tested patients. A 10-year-old girl with the novel variant c.1205G>A (p.Arg402Gln) presented with a new peculiar phenotype of PME without muscle atrophy. We expanded the phenotypic spectrum of ASAH1-related disorders and validated the biomarker C26-Ceramide for supporting diagnosis in symptomatic patients.

Slowly progressive distal muscle weakness: neuropathy or myopathy?

Nonaka myopathy is an autosomal recessive and slowly progressive distal myopathy. It is part of a rare group of myopathies predominantly affecting the distal limb musculature. Over 150 cases have been reported across the Middle East, Japan and Europe. We report the case of a 33-year-old woman presenting with symmetrical upper and lower limb weakness, most severely affecting the distal muscle groups. After extensive neurological investigation including neurophysiology, muscle biopsy and genetic analysis, she was finally diagnosed with Nonaka myopathy and treated conservatively with physiotherapy.

GNE myopathy in Roma patients homozygous for the p.I618T founder mutation.

GNE myopathy is an autosomal-recessive disorder caused by mutations in the GNE gene, encoding the key enzyme in the sialic acid biosynthetic pathway, UDP-N-acetylglucosamine 2-epimerase/N-acetyl mannosamine kinase. We studied 50 Bulgarian Roma patients homozygous for p.I618T, an ancient founder mutation in the kinase domain of the GNE gene, dating before the Gypsy exodus from North West India. The clinical features in the Bulgarian GNE group can be described with disease onset mostly in the third decade, but in individual cases, onset was as early as 10 years of age. The majority of patients had foot drop as the first symptom, but three patients developed hand weakness first. Muscle weakness was early and severe for the tibialis anterior, and minimal or late for quadriceps femoris, and respiratory muscles were only subclinically affected even in the advanced stages of the disease. During a 15-year follow-up period, 32 patients became non-ambulant. The average period between disease onset and loss of ambulation was 10.34 ± 4.31 years, ranging from 3 to 20 years. Our analysis of affected sib pairs suggested a possible role of genetic modifying factors, accounting for significant variation in disease severity.

[Anesthetic Management of Laparoscopic Nephrectomy for a Renal Cancer Patient with Distal Myopathy of Rimmed Vacuole].

A 56-year-old male with distal myopathy of rimmed vacuoles underwent laparoscopic nephrectomy. Anesthesia was induced with propofol, remifentanil and ketamine. Tracheal intubation using McGRATH was uneventful without using muscle relaxants. Then ultrasound-guided right thoracic paravertebral (TPVB) block was performed using 20 ml 0.75% ropivacaine with 10 ml 2% lidocaine by 3 injections of 10 ml each at T9 to T11. General anesthesia was maintained with propofol, remifentanil and ketamine monitoring bispectral index. Good surgical condition and pneumoperitoneum were maintained without using muscle relaxants. His postoperative course was smooth and uneventful, even though a small amount of fentanyl was administrated to relieve wound pain. This case suggests that McGRATH and ultrasound-guided TPVB can be one of the options to avoid using muscle relaxants in patient with neuromuscular disease.

Two families with MYH7 distal myopathy associated with cardiomyopathy and core formations.

INTRODUCTION: Laing distal myopathy is caused by MYH7 gene mutations. Multiple families have been reported with varying patterns of skeletal and cardiac involvement as well as histopathological findings. CASE SERIES: We report 2 families with p.Glu1508del mutation with detailed electrophysiological and muscle pathology findings. RESULTS: All patients displayed the classic phenotype with weakness starting in the anterior compartment of the legs with a "hanging great toe." It was followed by finger extensors involvement, relatively sparing the extensor indicis proprius, giving the appearance of a "pointing index" finger. All the affected individuals had a dilated cardiomyopathy and core formations on muscle biopsy. Unexpectedly, neurogenic changes were also observed in some individuals. Both families were initially misdiagnosed with either central core disease or hereditary neuropathy. CONCLUSIONS: Recognizing the classic phenotype, screening for cardiac involvement that may be clinically silent, and determining the mode of inheritance help with selecting the appropriate genetic test.

Impairment of respiratory function in late-onset distal myopathy due to MATR3 Mutation.

INTRODUCTION: Recently, mutations in the MATR3 gene were found to cause late-onset distal myopathy. The frequency and impact of respiratory involvement are not clear. METHODS: Respiratory parameters [maximum vital capacity (VCmax); forced expiratory volume (FEV1 ); peak expiratory flow (PEF), postural drop of VCmax from sitting to supine, maximum inspiratory muscle pressure (PImax), mouth occlusion pressure after 100 ms (P 0.1), peak cough flow, and blood-gas analysis] were monitored prospectively at baseline, and then 6 months and 12 months later in 8 patients with genetically confirmed MATR3 myopathy. RESULTS: All patients showed involvement of respiratory function. Six of 8 reported exertional dyspnea. At the end of follow-up, 5 of 8 had decreased VC, 7 of 8 had reduced PImax, and 5 of 7 had decreased partial pressure of oxygen (PO2 ). Within 12 months, respiratory parameters deteriorated non-significantly. No patient required non-invasive ventilation. CONCLUSIONS: There is a high risk of abnormal respiratory function with progressive worsening in MATR3 myopathy.

X-linked Recessive Distal Myopathy With Hypertrophic Cardiomyopathy Caused by a Novel Mutation in the FHL1 Gene.

FHL1 gene mutations are associated with reducing body myopathy, X-linked myopathy with postural muscle atrophy, scapuloperoneal myopathy, Emery-Dreifuss muscular dystrophy, and isolated hypertrophic cardiomyopathy. We describe a boy with a family history consistent with X-linked distal myopathy/cardiomyopathy. The boy first presented at age 14 years and was found to have distal wasting and weakness. Echocardiogram revealed hypertrophic cardiomyopathy. Muscle biopsy showed a vacuolar pathology with no reducing bodies. Sequencing of FHL1 revealed a novel hemizygous c.764G>C missense mutation in exon 8. This is the first report of a predominantly distal myopathy with hypertrophic cardiomyopathy occurring secondary to an FHL1 mutation.

A novel MYH7 Leu1453pro mutation resulting in Laing distal myopathy in an Irish family.

Authors describe clinical, pathological, imaging and genetic findings in the first Irish family with Laing distal myopathy in whom a novel mutation in the human slow ß-myosin heavy chain (MYH7) gene has been identified. A kindred of 14 over 6 generations included 6 individuals with childhood onset distal lower limb weakness in a scapula-peroneal distribution with subsequent proximal upper and lower limb weakness. Finger extensor weakness especially in the 3rd-5th fingers was present in each and two patients had "hanging big toe" sign. Three patients were non-ambulatory by middle-age. One patient developed cardiomyopathy and two patients had respiratory muscle impairment. Intriguingly, brain white matter lesions and epilepsy were present in three patients. Muscle biopsy revealed fibre-size variation, rimmed vacuoles, mild-extensive central nucleation, redundant and folded sarcolemmal membrane and Z band streaming. Genetic analysis revealed a novel heterozygous mutation in the MYH7 gene in one patient which co-segregated perfectly in the remaining 5 affected members and was absent in six unaffected members.

Achilles tendon lengthening for equinus foot with Miyoshi myopathy: a case report.

A 17-year-old male presented with reduced muscle strength in both lower limbs and demonstrated equinus foot (ankle equinus) in the right lower limb. Using dysferlin immunostaining, the patient was diagnosed with Miyoshi myopathy by the neurologist. Achilles tendon lengthening was performed, and a plantigrade foot without ankle equinus was achieved.

Distal myopathy with cachexia: an unrecognised phenotype caused by dominantly-inherited mitochondrial polymerase γ mutations.

BACKGROUND: The myopathy associated with mutations in the nuclear-encoded mitochondrial DNA maintenance gene POLG, coding for the catalytic subunit of DNA polymerase, is typically proximal with early ophthalmoplegia. RESULTS: We report two unrelated patients in whom a distal, mainly upper limb, myopathy was the predominant and early clinical feature. One patient also suffered with marked cachexia. DNA genomic sequence analysis identified novel dominant heterozygous missense POLG mutations (Leu896Arg and Tyr951His) located within the conserved catalytic polymerase domain of the protein in both cases. CONCLUSIONS: Distal upper limb myopathy/cachexia is not previously described with dominant POLG mutations and our observations further highlight the diverse clinical spectrum of POLG-related mitochondrial disorders. These data indicate that dominant POLG mutations should be considered in the differential diagnosis of distal upper limb predominant myopathy.

Novel ANO5 mutations causing hyper-CK-emia, limb girdle muscular weakness and Miyoshi type of muscular dystrophy.

INTRODUCTION: Mutations in the anoctamin 5 gene (ANO5) have been recently identified.They cause limb girdle muscular dystrophy (LGMD2L) and Miyoshi muscular dystrophy. METHODS: Clinical findings of four unrelated patients are reviewed. Mutation detection was performed by direct sequencing of the ANO5 exons. RESULTS: We identified four novel mutations in the ANO5 gene. In one patient, a novel homozygous mutation (c.1965G>C). In three patients, the recurrent heterozygous exon 5 c.191dupA mutation is combined with other variants to form a compound heterozygous state: in two cases, novel splice site mutations in intron 5 (c.295-1G>A) and in intron 14 (c.1407+5G>A), and in one case, a novel missense mutation in exon 4 (c.172C>T). CONCLUSIONS: The cases reported here should help to better understand the important role of mutation screening in the ANO5 gene in patients with adult onset muscular dystrophy and very high CK levels.

Distal myopathy with rimmed vacuoles and inflammation: a genetically proven case.

Distal myopathy with rimmed vacuoles (DMRV) is a major entity of distal myopathy. It is an autosomal recessive disorder and is due to mutations in the GNE gene that regulates the synthesis of sialic acid. Although reported predominantly from Japan, cases have been reported from other parts of the world. We report the first genetically proven case of DMRV from India in a 23-year-old male with gradual onset, progressive distal weakness of both lower limbs with features of inflammation in muscle biopsy.

Desmin A213V substitution represents a rare polymorphism but not a mutation and is more prevalent in patients with heart dilation of various origins.

Several desmin mutations have been described in patients with cardiomyopathies and distal myopathies. Among them, A213V substitution has been associated with three completely different clinical phenotypes: restrictive cardiomyopathy, dilated cardiomyopathy and isolated distal myopathy. However, the identification of this substitution also in control subjects has highlighted the question if the A213V shift represents a conditional mutation, giving rise to cardiomyopathy only in the presence of other predisposing factors. The aim of the present work was to study the potential role of this substitution in predisposing to heart dilation. Methods and results. We screened 108 patients with heart dilation due to ischemic heart disease, alcoholic cardiomyopathy or viral myocarditis, and 300 healthy controls for the presence of A213V substitution by direct sequencing and confirmed the results by site-specific restriction. In the control group A213V substitution was identified in 3 out of 300 patients, representing a rare polymorphism with a frequency of approximately 1%, which corresponds to the earlier reported frequency. In the study group A213V substitution was found in 5 out of 108 cases, corresponding to approximately 4.6% (p < 0.035). Therefore we conclude that A213V desmin substitution represents a conditional mutation, i.e. a rare polymorphism that plays a role as a predisposing factor resulting in maladaptive heart remodelling in the presence of other pathological factors.

Novel mutation in MYH7 gene associated with distal myopathy and cardiomyopathy.

A 25-year-old woman had childhood-onset muscle weakness and dilated cardiomyopathy. She exhibited predominantly distal weakness with early toe walking. Dilated cardiomyopathy required cardiac transplantation at age 15 years. We identified a de-novo, heterozygous, missense mutation, c.2348G>C (p. Arg783Pro), in exon 21 of the MYH7 gene, which encodes slow skeletal muscle fiber/ß-cardiac myosin heavy chain protein, that replaces a highly conserved arginine with a proline. This novel mutation that results in the unusual combined cardiac and skeletal muscle phenotype localizes to the essential light chain binding area, a region only previously shown to be mutated in hypertrophic cardiomyopathy.

Analysis of NCAM helps identify unusual phenotypes of hereditary inclusion-body myopathy.

BACKGROUND: Hereditary inclusion-body myopathy or distal myopathy with rimmed vacuoles (h-IBM/DMRV) is due to mutations of the UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) gene, which codes for an enzyme of the sialic acid biosynthetic pathway. By Western blot (WB) analysis, we have previously shown that in h-IBM/DMRV muscle, the neural cell adhesion molecule (NCAM) has increased electrophoretic mobility that reflects reduced sialylation of the protein. OBJECTIVE: To identify patients with h-IBM/DMRV with atypical clinical or pathologic phenotype using NCAM analysis and the possible cellular mechanism associated with the overall abnormal sialylation of NCAM observed in this disorder. METHODS: WB analysis of NCAM was performed on muscle biopsies of 84 patients with an uncharacterized muscle disorder who were divided in the following 2 groups: 1) 46 patients with a proximal muscle weakness in whom the main limb-girdle muscular dystrophy syndromes had been ruled out; and 2) 38 patients with a distal distribution of weakness in whom a neurogenic affection had been excluded. Patients in whom a reduced sialylation of NCAM was suspected were studied for the presence of GNE mutations. RESULTS: In 3 patients, we found that NCAM had increased electrophoretic mobility, thus suggesting an abnormal sialylation of the protein. The genetic study demonstrated that they all carried pathogenic GNE mutations. Further studies demonstrated that hyposialylated NCAM, showing increased electrophoretic mobility on WB, is expressed by nonregenerating fibers in h-IBM/DMRV muscle. CONCLUSIONS: WB analysis of NCAM may be instrumental in the identification of h-IBM/DMRV with atypical clinical or pathologic features.

Distal anterior compartment myopathy with early ankle contractures.

Dysferlinopathies exhibit marked heterogeneity in the initial distribution of muscle involvement at the onset of the disease. We describe a Japanese patient with dysferlinopathy who exhibited distal anterior compartment myopathy (DACM) with early contractures of the ankle, whose pedigree included patients with two other types of dysferlinopathy. The existence of three phenotypes of dysferlinopathy in one pedigree is reported, indicating the involvement of molecules other than dysferlin in the pathogenesis.

Distal myopathy with rimmed vacuoles and cerebellar atrophy.

Distal myopathies constitute a clinically and pathologically heterogeneous group of genetically determined neuromuscular disorders, where the distal muscles of the upper or lower limbs are affected. The disease of a 41-year-old male patient started with gait disturbances, when he was 25. The progression was slow, but after 16 years he became seriously disabled. Neurological examination showed moderate to severe weakness in distal muscles of all extremities, marked cerebellar sign and steppage gait. Muscle biopsy resulted in myopathic changes with rimmed vacuoles. Brain MRI scan showed cerebellar atrophy. This case demonstrates a rare association of distal myopathy and cerebellar atrophy.