Wen-Chen Liang

ETFDH mutations, CoQ10 levels, and respiratory chain activities in patients with riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency

Multiple acyl-CoA dehydrogenase deficiency (MADD) is a metabolic disorder due to dysfunction of electron transfer flavoprotein (ETF) or ETF-ubiquinone oxidoreductase (ETF-QO). Mutations in ETFDH, encoding ETF-QO have been associated with both riboflavin-responsive and non-responsive MADD as well as a myopathic form of CoQ(10) deficiency, although pathomechanisms responsible for these different phenotypes are not well-defined. We performed mutation analysis in four Taiwanese MADD patients. Three novel ETFDH mutations were identified in four patients and all harbored the p.A84T mutation. Muscle CoQ(10) levels and respiratory chain activities measured in two patients were normal. Three patients improved on riboflavin together with carnitine. Our results show that not all MADD patients have CoQ(10) deficiency. Based upon our data, riboflavin and carnitine may be the first-line treatment for MADD.

TMEM43 mutations in Emery-Dreifuss muscular dystrophy-related myopathy.

Emery‐Dreifuss muscular dystrophy (EDMD) is a genetically heterogeneous muscular disease that presents with muscular dystrophy, joint contractures, and cardiomyopathy with conduction defects. Mutations in several nuclear envelope protein genes have been associated with EDMD in less than half of patients, implying the existence of other causative and modifier genes. We therefore analyzed TMEM43, which encodes LUMA, a newly identified nuclear membrane protein and also a binding partner of emerin and lamins, to investigate whether LUMA may contribute to the pathomechanism of EDMD‐related myopathy.

The effect of hydroxyurea in spinal muscular atrophy cells and patients

BACKGROUND Spinal muscular atrophy (SMA) is a degenerative motor neuron disease caused by homozygous mutations of the survival motor neuron 1 (SMN1) gene. Effective treatment for SMA is unavailable at present. The aim of this study was to investigate the effect of hydroxyurea (HU) in SMA cells and patients. MATERIALS AND METHODS Fifteen SMA lymphoid and three fibroblast cell lines, 2 from SMA patients and 1 control, were treated with HU at different concentrations, and 33 patients (types II, III) randomized into three groups on different HU dosage, 20, 30, 40 mg/kg/day, were treated for 8 weeks and followed up for another drug-free 8 weeks. The effect of HU on SMN2 gene expression and clinical manifestations was evaluated. RESULTS After treatment, in vitro, full-length mRNA level and gems number increased significantly, and hnRNP A1 protein decreased. In vivo, there were slight increases in muscle strength scores at 4 weeks and full-length SMN mRNA at 8 weeks in 30 mg/kg/day subgroup. CONCLUSIONS Treating with HU enhanced SMN2 gene expression in SMA cells and showed slight trend towards improvement in some clinical outcome measures in SMA patients which suggests HU may be safe to use in SMA patients but larger randomized, placebo-controlled, double-blind trials are needed to further investigate its efficacy.

Lipid Storage Myopathy

Lipid storage myopathy (LSM) is pathologically characterized by prominent lipid accumulation in muscle fibers due to lipid dysmetabolism. Although extensive molecular studies have been performed, there are only four types of genetically diagnosable LSMs: primary carnitine deficiency (PCD), multiple acyl-coenzyme A dehydrogenase deficiency (MADD), neutral lipid storage disease with ichthyosis, and neutral lipid storage disease with myopathy. Making an accurate diagnosis, by specific laboratory tests including genetic analyses, is important for LSM as some of the patients are treatable: individuals with PCD show dramatic improvement with high-dose oral L-carnitine supplementation and increasing evidence indicates that MADD due to ETFDH mutations is riboflavin responsive.

Congenital muscular dystrophy with fatty liver and infantile-onset cataract caused by TRAPPC11 mutations: broadening of the phenotype

BackgroundTransport protein particle (TRAPP) is a multiprotein complex involved in endoplasmic reticulum-to-Golgi trafficking. Zebrafish with a mutation in the TRAPPC11 orthologue showed hepatomegaly with steatosis and defects in visual system development. In humans, TRAPPC11 mutations have been reported in only three families showing limb-girdle muscular dystrophy (LGMD) or myopathy with movement disorders and intellectual disability.MethodsWe screened muscular dystrophy genes using next-generation sequencing and performed associated molecular and biochemical analyses in a patient with fatty liver and cataract in addition to infantile-onset muscle weakness.ResultsWe identified the first Asian patient with TRAPPC11 mutations. Muscle pathology demonstrated typical dystrophic changes and liver biopsy revealed steatosis. The patient carried compound heterozygous mutations of a previously reported missense and a novel splice-site mutation. The splice-site change produced two aberrantly-spliced transcripts that were both predicted to result in translational frameshift and truncated proteins. Full-length TRAPPC11 protein was undetectable on immunoblotting.ConclusionThis report widens the phenotype of TRAPPC11-opathy as the patient showed the following: (1) congenital muscular dystrophy phenotype rather than LGMD; (2) steatosis and infantile-onset cataract, both not observed in previously reported patients; but (3) no ataxia or abnormal movement, clearly indicating that TRAPPC11 plays a physiological role in multiple tissues in human.

High resolution melting analysis facilitates mutation screening of ETFDH gene: Applications in riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency

BACKGROUND Multiple acyl-CoA dehydrogenase deficiency (MADD) or gluaric aciduria type II is an autosomal recessive disease caused by defects in mitochondrial electron transfer system and metabolism of fatty acid. Recently, ETFDH mutations were reported to be major causes of riboflavin-responsive MADD. The present study is aimed at screening ETFDH mutations. METHODS High resolution melting (HRM) analysis was performed to screen ETFDH mutations. Genomic DNA was extracted from peripheral blood samples of the 9 patients with MADD and normal controls. Total 13 exons of ETFDH were screened by HRM analysis. The results were subsequently confirmed by direct DNA sequencing. RESULTS This diagnostic strategy proved to be feasible in detecting 3 known (c.250G>A, c380T>A, c.524G>T) and 1 novel (c.1831G>A) ETFDH mutations. Each mutation could be readily and accurately identified in the difference plot curves. We estimated the carrier frequency of the hotspot mutation, c.250G>A, in the Taiwanese population to be 1:125 (0.8%). CONCLUSIONS HRM analysis can be successfully applied to screen ETFDH mutations. Since riboflavin-responsive MADD is often treatable, especially with mutations in ETFDH, identifying ETFDH mutations is crucial for these patients.

Muscle glycogen storage disease 0 presenting recurrent syncope with weakness and myalgia.

Muscle glycogen storage disease 0 (GSD0) is caused by glycogen depletion in skeletal and cardiac muscles due to deficiency of glycogen synthase 1 (GYS1), which is encoded by the GYS1 gene. Only two families with this disease have been identified. We report a new muscle GSD0 patient, a Japanese girl, who had been suffering from recurrent attacks of exertional syncope accompanied by muscle weakness and pain since age 5 years until she died of cardiac arrest at age 12. Muscle biopsy at age 11 years showed glycogen depletion in all muscle fibers. Her loss of consciousness was gradual and lasted for hours, suggesting that the syncope may not be simply caused by cardiac event but probably also contributed by metabolic distress.

Combined Noninvasive Ventilation and Mechanical In-Exsufflator in the Treatment of Pediatric Acute Neuromuscular Respiratory Failure

The present study aims to evaluate the efficacy and complications of combined noninvasive ventilation (NIV) and assisted coughing by mechanical in‐exsufflator (MIE) for acute respiratory failure (ARF) in children with neuromuscular disease (NMD).

Correlation between muscle involvement, phenotype and D4Z4 fragment size in facioscapulohumeral muscular dystrophy

This study aimed to evaluate muscle involvement pattern and correlate the lesions on muscle imaging with clinical features and D4Z4 fragment size in 24 patients with facioscapulohumeral muscular dystrophy (FSHD). The grading of the muscle image detected by computed tomography (CT) was based on a four-point semi-quantitative visual scale. On muscle CT, the most affected muscle was trapezium, followed by hamstrings. CT image identified hamstrings involvement rather than shoulder-girdle in clinically asymptomatic subjects. CT image also showed that axial muscle was affected in one-third of patients which appeared even earlier than clinical manifestation. Strong correlations between CT findings, serum creatine kinase level and clinical severity scores were also found. Asymmetric involvement was more evident on CT image than it identified in manual muscle strength testing. Inverse correlation between CT grade and D4Z4 fragment size was clearly demonstrated. These findings suggest muscle CT will be helpful for the process of early intervention in FSHD, even in subjects in a preclinical status.

Limb-girdle muscular dystrophy type 2I is not rare in Taiwan

Alpha-dystroglycanopathy is caused by the glycosylation defects of α-dystroglycan (α-DG). The clinical spectrum ranges from severe congenital muscular dystrophy (CMD) to later-onset limb girdle muscular dystrophy (LGMD). Among all α-dystroglycanopathies, LGMD type 2I caused by FKRP mutations is most commonly seen in Europe but appears to be rare in Asia. We screened uncategorized 40 LGMD and 10 CMD patients by immunohistochemistry for α-DG and found 7 with reduced α-DG immunostaining. Immunoblotting with laminin overlay assay confirmed the impaired glycosylation of α-DG. Among them, five LGMD patients harbored FKRP mutations leading to the diagnosis of LGMD2I. One common mutation, c.948delC, was identified and cardiomyopathy was found to be very common in our cohort. Muscle images showed severe involvement of gluteal muscles and posterior compartment at both thigh and calf levels, which is helpful for the differential diagnosis. Due to the higher frequency of LGMD2I with cardiomyopathy in our series, the early introduction of mutation analysis of FKRP in undiagnosed Taiwanese LGMD patients is highly recommended.