Lipid storage myopathy associated with sertraline treatment is an acquired mitochondrial disorder with respiratory chain deficiency.

Lipid storage myopathies are considered inborn errors of metabolism affecting the fatty acid metabolism and leading to accumulation of lipid droplets in the cytoplasm of muscle fibers. Specific diagnosis is based on investigation of organic aids in urine, acylcarnitines in blood and genetic testing. An acquired lipid storage myopathy in patients treated with the antidepressant drug sertraline, a serotonin reuptake inhibitor, has recently emerged as a new tentative differential diagnosis.

Abnormal expression of myosin heavy chains in early postnatal stages of spinal muscular atrophy type I at single fibre level.

Objective: We investigated myosin heavy chain (MyHC) isoform expression at early postnatal stages of clinically and genetically confirmed spinal muscular atrophy type 1 (SMA1) patients, in order to study the muscle fibre differentiation compared to age-matched controls at single fibre level.

Methods: Open skeletal muscle biopsies were performed from the quadriceps muscle in four SMA1 patients and three age-matched controls. Standard techniques were used for immunohistochemistry of embryonic and foetal MyHCs.

Proteomic profiling of polyglucosan bodies associated with glycogenin-1 deficiency in skeletal muscle.

Aims: Polyglucosan storage disorders represent an emerging field within neurodegenerative and neuromuscular conditions, including Lafora disease (EPM2A, EPM2B), adult polyglucosan body disease (APBD, GBE1), polyglucosan body myopathies associated with RBCK1 deficiency (PGBM1, RBCK1) or glycogenin-1 deficiency (PGBM2, GYG1). While the storage material primarily comprises glycans, this study aimed to gain deeper insights into the protein components by proteomic profiling of the storage material in glycogenin-1 deficiency.

Methods: We employed molecular genetic analyses, quantitative mass spectrometry of laser micro-dissected polyglucosan bodies and muscle homogenate, immunohistochemistry and western blot analyses in muscle tissue from a 45-year-old patient with proximal muscle weakness from late teenage years due to polyglucosan storage myopathy.

Inclusion body myositis with early onset: a population-based study.

Introduction: Inclusion body myositis (IBM), an inflammatory myopathy with progressive weakness without efficient treatment, typically presents after 45 years of age and younger patients are sparsely studied.

Methods: In a population-based study during a 33-year period, 142 patients with IBM were identified in western Sweden. Six patients fell outside the European Neuromuscular Centre 2011 criteria for IBM due to young age at symptom onset, verified by a muscle biopsy < 50 years of age.

Ribonuclease inhibitor 1 (RNH1) deficiency cause congenital cataracts and global developmental delay with infection-induced psychomotor regression and anemia.

Ribonuclease inhibitor 1, also known as angiogenin inhibitor 1, encoded by RNH1, is a ubiquitously expressed leucine-rich repeat protein, which is highly conserved in mammalian species. Inactivation of rnh1 in mice causes an embryonically lethal anemia, but the exact biological function of RNH1 in humans remains unknown and no human genetic disease has so far been associated with RNH1. Here, we describe a family with two out of seven siblings affected by a disease characterized by congenital cataract, global developmental delay, myopathy and psychomotor deterioration, seizures and periodic anemia associated with upper respiratory tract infections.

The Swedish COG6-CDG experience and a comprehensive literature review.

Here, we present the first two Swedish cases of Conserved Oligomeric Golgi complex subunit 6-congenital disorders of glycosylation (COG6-CDG). Their clinical symptoms include intellectual disability, Attention Deficit/Hyperactivity Disorder (ADHD), delayed brain myelinization, progressive microcephaly, joint laxity, hyperkeratosis, frequent infections, and enamel hypoplasia. In one family, compound heterozygous variants in were identified, where one (c.

Dominantly inherited myosin IIa myopathy caused by aberrant splicing of MYH2.

Background: Myosin heavy chain (MyHC) isoforms define the three major muscle fiber types in human extremity muscles. Slow beta/cardiac MyHC (MYH7) is expressed in type 1 muscle fibers. MyHC IIa (MYH2) and MyHC IIx (MYH1) are expressed in type 2A and 2B fibers, respectively.

Respiratory chain dysfunction in perifascicular muscle fibres in patients with dermatomyositis is associated with mitochondrial DNA depletion.

Aims: Patients with dermatomyositis (DM) suffer from reduced aerobic metabolism contributing to impaired muscle function, which has been linked to cytochrome c oxidase (COX) deficiency in muscle tissue. This mitochondrial respiratory chain dysfunction is typically seen in perifascicular regions, which also show the most intense inflammatory reaction along with capillary loss and muscle fibre atrophy. The objective of this study was to investigate the pathobiology of the oxidative phosphorylation deficiency in DM.

Thermo-sensitive mitochondrial trifunctional protein deficiency presenting with episodic myopathy.

Mitochondrial trifunctional protein (MTP) is involved in long-chain fatty acid β-oxidation (lcFAO). Deficiency of one or more of the enzyme activities as catalyzed by MTP causes generalized MTP deficiency (MTPD), long-chain hydroxyacyl-CoA dehydrogenase deficiency (LCHADD), or long-chain ketoacyl-CoA thiolase deficiency (LCKATD). When genetic variants result in thermo-sensitive enzymes, increased body temperature (e.

Four Swedish cases of CSF1R-related leukoencephalopathy: Visualization of clinical phenotypes.

Unlabelled: Colony stimulating factor 1 receptor (CSF1R)-related leukoencephalopathy is a rare, genetic disease caused by heterozygous mutations in the CSF1R gene with rapidly progressive neurodegeneration, behavioral, cognitive, motor disturbances.

Objective: To describe four cases of CSF1R-related leukoencephalopathy from three families with two different pathogenic mutations in the tyrosine kinase domain of CSF1R and to develop an integrated presentation of inter-individual diversity of clinical presentations.

Methods: This is an observational study of a case series.

Expression pattern of mitochondrial respiratory chain enzymes in skeletal muscle of patients with mitochondrial myopathy associated with the homoplasmic m.14674T>C variant.

Two homoplasmic variants in tRNA (m.14674T>C/G) are associated with reversible infantile respiratory chain deficiency. This study sought to further characterize the expression of the individual mitochondrial respiratory chain complexes and to describe the natural history of the disease.

The phenotypic variability and natural history of NARS2 associated disease.

Introduction: The phenotypic variability of NARS2 associated disease is vast, yet not thoroughly explored. We present the phenotypic and genetic features of 2 siblings with early-onset mitochondrial encephalopathy due to pathogenic variant in NARS2, along with the results from a systematic literature review.

Aims: To better delineate the phenotypic variability and natural history of NARS2 associated disease.

Functional analysis of a novel POLγA mutation associated with a severe perinatal mitochondrial encephalomyopathy.

Mutations in the mitochondrial DNA polymerase gamma catalytic subunit (POLγA) compromise the stability of mitochondrial DNA (mtDNA) by leading to mutations, deletions and depletions in mtDNA. Patients with mutations in POLγA often differ remarkably in disease severity and age of onset. In this work we have studied the functional consequence of POLγA mutations in a patient with an uncommon and a very severe disease phenotype characterized by prenatal onset with intrauterine growth restriction, lactic acidosis from birth, encephalopathy, hepatopathy, myopathy, and early death.

Mitochondrial DNA variants in inclusion body myositis characterized by deep sequencing.

Muscle pathology in inclusion body myositis (IBM) typically includes inflammatory cell infiltration, muscle fibers with rimmed vacuoles and cytochrome c oxidase (COX)-deficient fibers. Previous studies have revealed clonal expansion of large mitochondrial DNA (mtDNA) deletions in the COX-deficient muscle fibers. Technical limitations have prevented complete investigations of the mtDNA deletions and other mtDNA variants.

Accurate mapping of mitochondrial DNA deletions and duplications using deep sequencing.

Deletions and duplications in mitochondrial DNA (mtDNA) cause mitochondrial disease and accumulate in conditions such as cancer and age-related disorders, but validated high-throughput methodology that can readily detect and discriminate between these two types of events is lacking. Here we establish a computational method, MitoSAlt, for accurate identification, quantification and visualization of mtDNA deletions and duplications from genomic sequencing data. Our method was tested on simulated sequencing reads and human patient samples with single deletions and duplications to verify its accuracy.

Pathogenic Variants in the Myosin Chaperone UNC-45B Cause Progressive Myopathy with Eccentric Cores.

The myosin-directed chaperone UNC-45B is essential for sarcomeric organization and muscle function from Caenorhabditis elegans to humans. The pathological impact of UNC-45B in muscle disease remained elusive. We report ten individuals with bi-allelic variants in UNC45B who exhibit childhood-onset progressive muscle weakness.

Progressive external ophthalmoplegia associated with novel MT-TN mutations.

Objectives: To describe two patients with progressive external ophthalmoplegia (PEO) and mitochondrial myopathy associated with mutations in mitochondrial DNA, encoding the tRNA gene (MT-TN), which have not previously been published with clinical descriptions.

Materials & Methods: Two unrelated patients with PEO were clinically examined. Muscle biopsy was performed and investigated by exome sequencing, enzyme histochemistry, and immunohistochemistry.

COX deficiency and leukoencephalopathy due to a novel homozygous mutation.

Objective: To describe the long-term follow-up and pathogenesis in a child with leukoencephalopathy and cytochrome c oxidase (COX) deficiency due to a novel homozygous nonsense mutation in .

Methods: The patient was clinically investigated at 3, 5, 9, and 25 years of age. Brain MRI, repeat muscle biopsies with biochemical, morphologic, and protein expression analyses were performed, and whole-genome sequencing was used for genetic analysis.

RBCK1-related disease: A rare multisystem disorder with polyglucosan storage, auto-inflammation, recurrent infections, skeletal, and cardiac myopathy-Four additional patients and a review of the current literature.

In this article, we report four new patients, from three kindreds, with pathogenic variants in RBCK1 and a multisystem disorder characterised by widespread polyglucosan storage. We describe the clinical presentation of progressive skeletal and cardiac myopathy, combined immunodeficiencies and auto-inflammation, illustrate in detail the histopathological findings in multiple tissue types, and report muscle MRI findings.

Deep sequencing of mitochondrial DNA and characterization of a novel mutation in a patient with arPEO.

Objective: To determine the pathogenicity of a novel mutation in a man with late-onset autosomal recessive progressive external ophthalmoplegia using clinical, molecular, and biochemical analyses.

Methods: A multipronged approach with detailed neurologic examinations, muscle biopsy analyses, molecular genetic studies, and in vitro biochemical characterization.

Results: The patient had slowly progressive bilateral ptosis and severely reduced horizontal and vertical gaze.

Functional characterization of GYG1 variants in two patients with myopathy and glycogenin-1 deficiency.

Glycogen storage disease XV is caused by variants in the glycogenin-1 gene, GYG1, and presents as a predominant skeletal myopathy or cardiomyopathy. We describe two patients with late-onset myopathy and biallelic GYG1 variants. In patient 1, the novel c.

An AARS variant as the likely cause of Swedish type hereditary diffuse leukoencephalopathy with spheroids.

Swedish type Hereditary Diffuse Leukoencephalopathy with Spheroids (HDLS-S) is a severe adult-onset leukoencephalopathy with the histopathological hallmark of neuraxonal degeneration with spheroids, described in a large family with a dominant inheritance pattern. The initial stage of the disease is dominated by frontal lobe symptoms that develop into a rapidly advancing encephalopathy with pyramidal, deep sensory, extrapyramidal and optic tract symptoms. Median survival is less than 10 years.

Deep morphological analysis of muscle biopsies from type III glycogenesis (GSDIII), debranching enzyme deficiency, revealed stereotyped vacuolar myopathy and autophagy impairment.

Glycogen storage disorder type III (GSDIII), or debranching enzyme (GDE) deficiency, is a rare metabolic disorder characterized by variable liver, cardiac, and skeletal muscle involvement. GSDIII manifests with liver symptoms in infancy and muscle involvement during early adulthood. Muscle biopsy is mainly performed in patients diagnosed in adulthood, as routine diagnosis relies on blood or liver GDE analysis, followed by AGL gene sequencing.

Glycogenin is Dispensable for Glycogen Synthesis in Human Muscle, and Glycogenin Deficiency Causes Polyglucosan Storage.

Context: Glycogenin is considered to be an essential primer for glycogen biosynthesis. Nevertheless, patients with glycogenin-1 deficiency due to biallelic GYG1 (NM_004130.3) mutations can store glycogen in muscle.