Muscle histopathology in nebulin-related nemaline myopathy : ultrastrastructural findings correlated to disease severity and genotype

Peer reviewe

Skeletal Muscle Biopsy Analysis in Reducing Body Myopathy and Other Fhl1-related Disorders

FHL1 mutations have been associated with various disorders that include reducing body myopathy (RBM), Emery-Dreifuss-like muscular dystrophy, isolated hypertrophic cardiomyopathy, and some overlapping conditions. We report a detailed histochemical, immunohistochemical, electron microscopic, and immunoelectron microscopic analyses of muscle biopsies from 18 patients carrying mutations in FHL1: 14 RBM patients (Group 1), 3 Emery-Dreifuss muscular dystrophy patients (Group 2), and 1 patient with hypertrophic cardiomyopathy and muscular hypertrophy (Group 2). Group 1 muscle biopsies consistently showed RBs associated with cytoplasmic bodies. The RBs showed prominent FHL1 immunoreactivity whereas desmin, alpha B-crystallin, and myotilin immunoreactivity surrounded RBs. By electron microscopy, RBs were composed of electron-dense tubulofilamentous material that seemed to spread progressively between the myofibrils and around myonuclei. By immunoelectron microscopy, FHL1 protein was found exclusively inside RBs. Group 2 biopsies showed mild dystrophic abnormalities without RBs; only minor nonspecific myofibrillar abnormalities were observed under electron microscopy. Molecular analysis revealed missense mutations in the second FHL1 LIM domain in Group 1 patients and ins/del or missense mutations within the fourth FHL1 LIM domain in Group 2 patients. Our findings expand the morphologic features of RBM, clearly demonstrate the localization of FHL1 in RBs, and further illustrate major morphologic differences among different FHL1-related myopathies

Clinical and molecular characterization of mitochondrial DNA disorders in a group of Argentinian pediatric patients

Objective: To describe the clinical and molecular features of a group of Argentinian pediatric patients with mitochondrial DNA (mtDNA) disorders, and to evaluate the results of the implementation of a classical approach for the molecular diagnosis of mitochondrial diseases. Methods: Clinical data from 27 patients with confirmed mtDNA pathogenic variants were obtained from a database of 89 patients with suspected mitochondrial disease, registered from 2014 to 2020. Clinical data, biochemical analysis, neuroimaging findings, muscle biopsy and molecular studies were analyzed. Results: Patients were 18 females and 9 males, with ages at onset ranging from 1 week to 14 years (median = 4 years). The clinical phenotypes were: mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome (n = 11), Leigh syndrome (n = 5), Kearns-Sayre syndrome (n = 3), Chronic Progressive External Ophthalmoplegia (n = 2), Leber hereditary optic neuropathy (n = 2), myoclonic epilepsy associated with ragged-red fibers (n = 1) and reversible infantile myopathy with cytochrome-C oxidase deficiency (n = 3). Most of the patients harbored pathogenic single nucleotide variants, mainly involving mt-tRNA genes, such as MT-TL1, MT-TE and MT-TK. Other point variants were found in complex I subunits, like MT-ND6, MT-ND4, MT-ND5; or in MT-ATP6. The m.13513G > A variant in MT-ND5 and the m.9185 T > C variant in MT-ATP6 were apparently de novo. The rest of the patients presented large scale-rearrangements, either the ?common? deletion or a larger deletion. Conclusions: This study highlights the clinical and genetic heterogeneity of pediatric mtDNA disorders. All the cases presented with classical phenotypes, being MELAS the most frequent. Applying classical molecular methods, it was possible to achieve a genetic diagnosis in 30% of the cases, suggesting that this is an effective first approach, especially for those centers from low-middle income countries, leaving NGS studies for those patients with inconclusive results.Fil: Loos, Mariana Amina. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Gomez, Gimena. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Mayorga, Lía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Caraballo, Roberto Horacio. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Eiroa, Hernán Diego. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Obregon, María Gabriela. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Rugilo, Carlos. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Lubieniecki, Fabiana. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Taratuto, Ana Lía. No especifíca;Fil: Saccoliti, María. No especifíca;Fil: Alonso, Cristina Noemí. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Aráoz, Hilda Verónica. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentin

Argentine consensus on the diagnosis, monitoring and treatment of Pompe disease

Introducción: La enfermedad de Pompe (EP) es un desorden metabólico autosómico recesivo infrecuente que se produce por ausencia o deficiencia de la enzima lisosomal alfa-glucosidasa ácida en los tejidos de los individuos afectados. Objetivo: El objetivo del presente consenso es revisar las pautas actuales y brindar recomendaciones para un correcto diagnóstico, evaluación, manejo y tratamiento de los pacientes con EP. Métodos: Se organizó un consenso que reunió profesionales nacionales y un invitado extranjero con experiencia en la EP en las áreas de clínica médica, clínica pediátrica, diagnóstico de laboratorio, neuropatología, neumonología, nutrición, neurología, enfermedades metabólicas, enfermedades neuromusculares (ENM) y rehabilitación de pacientes con ENM. Se realizó una revisión bibliográfica de las publicaciones y los artículos relevantes sobre EP existentes hasta la fecha, en forma individual y en reuniones en pequeños grupos, organizados según el área de trabajo y la especialidad. Los términos finales del documento fueron consensuados por todo el grupo de trabajo. Cada participante proporcionó su declaración de conflicto de intereses. Conclusiones: Se elaboró el Consenso Argentino para la Enfermedad de Pompe, considerando aspectos de la fisiopatología, la clínica, el diagnóstico y el tratamiento de esta enfermedad. Tratándose de una afección infrecuente, en la que los datos disponibles son limitados, las presentes recomendaciones deben ser consideradas como opinión de expertos.Introduction: Pompe disease (PD) is a rare autosomal recessive metabolic disorder which is caused by the absence or deficiency of the acid alpha-glucosidase lysosomal enzyme in the tissues of affected individuals. Objective: The objective of this consensus is to review the current guidelines and provide recommendations for a correct diagnosis, evaluation, management, and treatment of patients with PD. Methods: We organized a consensus with a foreign guest and national professionals experienced in PD in the areas of clinic, pediatric clinic, laboratory diagnosis, neuropathology, neumonology, nutrition, neurology, metabolic diseases, neuromuscular diseases (NMD) and rehabilitation of patients with MND. We conducted a literature review of the existing publications and articles relevant to EP up to date, individually and in small group meetings organized by field of work and specialty. The final terms of the document were agreed upon by the entire working group. Each participant provided their declaration of conflict of interests. Conclusions: The Argentine Consensus for Pompe disease was developed, considering aspects of the pathophysiology, clinical manifestations, diagnosis and treatment of this disease. Being a rare condition for which the available data are limited, these recommendations should be considered as expert opinion.Fil: Dubrovsky, Alberto. Fundación Favaloro; ArgentinaFil: Fulgenzi, Ernesto. Unidad Asistencial Doctor César Milstein; ArgentinaFil: Amartino, Hernán. Hospital Universitario Austral. Servicio de Neurología Infantil; ArgentinaFil: Carlés, Daniel. Hospital Perrando. Servicio de Neumonología; ArgentinaFil: Corderi, José. Fundación Favaloro; ArgentinaFil: de Vito, Eduardo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Médicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fainboim, Alejandro. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Ferradás, Nélida. International Life Sciences Institute ; ArgentinaFil: Guelbert, Norberto. Hospital de Niños de la Santísima Trinidad. Sección de Enfermedades Metabólicas; ArgentinaFil: Lubieniecki, Fabiana. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Mazia, Claudio. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Médicas; ArgentinaFil: Mesa, Lilia. Fundación Favaloro; ArgentinaFil: Monges, Soledad. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Pesquero, Joao. Universidade de Sao Paulo; BrasilFil: Reisin, Ricardo. Hospital Británico de Buenos Aires; ArgentinaFil: Rugiero, Marcelo. Hospital Italiano; ArgentinaFil: Schenone, Andrea. Fundación para el Estudio de Enfermedades Neurometabólicas; ArgentinaFil: Szlago, Marina. Fundación para el Estudio de Enfermedades Neurometabólicas; ArgentinaFil: Taratuto, Ana Lía. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Zgaga, Marisa. Instituto de Lucha Antipoliomielítica y Rehabilitación del Lisiado; Argentina. Hospital Escuela Eva Perón. Servicio de Rehabilitación; Argentin

Skeletal Muscle Biopsy Analysis in Reducing Body Myopathy and Other Fhl1-related Disorders

FHL1 mutations have been associated with various disorders that include reducing body myopathy (RBM), Emery-Dreifuss-like muscular dystrophy, isolated hypertrophic cardiomyopathy, and some overlapping conditions. We report a detailed histochemical, immunohistochemical, electron microscopic, and immunoelectron microscopic analyses of muscle biopsies from 18 patients carrying mutations in FHL1: 14 RBM patients (Group 1), 3 Emery-Dreifuss muscular dystrophy patients (Group 2), and 1 patient with hypertrophic cardiomyopathy and muscular hypertrophy (Group 2). Group 1 muscle biopsies consistently showed RBs associated with cytoplasmic bodies. The RBs showed prominent FHL1 immunoreactivity whereas desmin, alpha B-crystallin, and myotilin immunoreactivity surrounded RBs. By electron microscopy, RBs were composed of electron-dense tubulofilamentous material that seemed to spread progressively between the myofibrils and around myonuclei. By immunoelectron microscopy, FHL1 protein was found exclusively inside RBs. Group 2 biopsies showed mild dystrophic abnormalities without RBs; only minor nonspecific myofibrillar abnormalities were observed under electron microscopy. Molecular analysis revealed missense mutations in the second FHL1 LIM domain in Group 1 patients and ins/del or missense mutations within the fourth FHL1 LIM domain in Group 2 patients. Our findings expand the morphologic features of RBM, clearly demonstrate the localization of FHL1 in RBs, and further illustrate major morphologic differences among different FHL1-related myopathies

Loss of Sarcomeric Scaffolding as a Common Baseline Histopathologic Lesion in Titin-Related Myopathies

International audienceTitin-related myopathies are heterogeneous clinical conditions associated with mutations in TTN. To define their histopathologic boundaries and try to overcome the difficulty in assessing the pathogenic role of TTN variants, we performed a thorough morphological skeletal muscle analysis including light and electron microscopy in 23 patients with different clinical phenotypes presenting pathogenic autosomal dominant or autosomal recessive (AR) mutations located in different TTN domains. We identified a consistent pattern characterized by diverse defects in oxidative staining with prominent nuclear internalization in congenital phenotypes (AR-CM) (n = 10), ± necrotic/regenerative fibers, associated with endomysial fibrosis and rimmed vacuoles (RVs) in AR early-onset Emery-Dreifuss-like (AR-ED) (n = 4) and AR adult-onset distal myopathies (n = 4), and cytoplasmic bodies (CBs) as predominant finding in hereditary myopathy with early respiratory failure (HMERF) patients (n = 5). Ultrastructurally, the most significant abnormalities, particularly in AR-CM, were multiple narrow core lesions and/or clear small areas of disorganizations affecting one or a few sarcomeres with M-band and sometimes A-band disruption and loss of thick filaments. CBs were noted in some AR-CM and associated with RVs in HMERF and some AR-ED cases. As a whole, we described recognizable histopathological patterns and structural alterations that could point toward considering the pathogenicity of TTN mutations