Congenital muscular dystrophies

Novel Radiological Brain Anomalies in a Patient with Congenital Muscular Dystrophy due to FKRP Mexican Founder Mutation c.1387A > G: Review of the Literature

Mutations in the FKRP gene result in phenotypes with severe forms of congenital muscular dystrophies (CMD) and limb-girdle muscular dystrophies. We present a Mexican patient with a pathogenic homozygous mutation in the FKRP gene (c.1387A > G, p.Asn463Asp) and CMD with radiological brain anomalies as disseminated hyperintensity lesions and discrete generalized cortical atrophy. These findings have not been reported to the best of our knowledge in other patients with the same mutation. The mutation c.1387A > G, p.Asn463Asp in the FKRP gene has been described to have a founder effect in central Mexico, since all the patients described to date are of Hispanic origin. Therefore, we emphasize studying mutations in the FKRP gene in Hispanic pediatric patients with clinical suspicion of CMD. Clinical and molecular diagnosis of specific CMD subtypes is needed to help clarify the prognosis, management, and genetic counseling to the patient and families.

Metabolic Cardiomyopathies and Cardiac Defects in Inherited Disorders of Carbohydrate Metabolism: A Systematic Review

Heart failure (HF) is a progressive chronic disease that remains a primary cause of death worldwide, affecting over 64 million patients. HF can be caused by cardiomyopathies and congenital cardiac defects with monogenic etiology. The number of genes and monogenic disorders linked to development of cardiac defects is constantly growing and includes inherited metabolic disorders (IMDs). Several IMDs affecting various metabolic pathways have been reported presenting cardiomyopathies and cardiac defects. Considering the pivotal role of sugar metabolism in cardiac tissue, including energy production, nucleic acid synthesis and glycosylation, it is not surprising that an increasing number of IMDs linked to carbohydrate metabolism are described with cardiac manifestations. In this systematic review, we offer a comprehensive overview of IMDs linked to carbohydrate metabolism presenting that present with cardiomyopathies, arrhythmogenic disorders and/or structural cardiac defects. We identified 58 IMDs presenting with cardiac complications: 3 defects of sugar/sugar-linked transporters (GLUT3, GLUT10, THTR1); 2 disorders of the pentose phosphate pathway (G6PDH, TALDO); 9 diseases of glycogen metabolism (GAA, GBE1, GDE, GYG1, GYS1, LAMP2, RBCK1, PRKAG2, G6PT1); 29 congenital disorders of glycosylation (ALG3, ALG6, ALG9, ALG12, ATP6V1A, ATP6V1E1, B3GALTL, B3GAT3, COG1, COG7, DOLK, DPM3, FKRP, FKTN, GMPPB, MPDU1, NPL, PGM1, PIGA, PIGL, PIGN, PIGO, PIGT, PIGV, PMM2, POMT1, POMT2, SRD5A3, XYLT2); 15 carbohydrate-linked lysosomal storage diseases (CTSA, GBA1, GLA, GLB1, HEXB, IDUA, IDS, SGSH, NAGLU, HGSNAT, GNS, GALNS, ARSB, GUSB, ARSK). With this systematic review we aim to raise awareness about the cardiac presentations in carbohydrate-linked IMDs and draw attention to carbohydrate-linked pathogenic mechanisms that may underlie cardiac complications.

Neurogenetic motor disorders

Advances in the field of neurogenetics have practical applications in rapid diagnosis on blood and body fluids to extract DNA, obviating the need for invasive investigations. The ability to obtain a presymptomatic diagnosis through genetic screening and biomarkers can be a guide to life-saving disease-modifying therapy or enzyme replacement therapy to compensate for the deficient disease-causing enzyme. The benefits of a comprehensive neurogenetic evaluation extend to family members in whom identification of the causal gene defect ensures carrier detection and at-risk counseling for future generations. This chapter explores the many facets of the neurogenetic evaluation in adult and pediatric motor disorders as a primer for later chapters in this volume and a roadmap for the future applications of genetics in neurology.

NINDS Common Data Elements for Congenital Muscular Dystrophy Clinical Research: A National Institute for Neurological Disorders and Stroke Project

BACKGROUND

A Congenital Muscular Dystrophy (CMD) Working Group (WG) consisting of international experts reviewed common data elements (CDEs) previously developed for other neuromuscular diseases (NMDs) and made recommendations for all types of studies on CMD.

OBJECTIVES

To develop a comprehensive set of CDEs, data definitions, case report forms and guidelines for use in CMD clinical research to facilitate interoperability of data collection, as part of the CDE project at the National Institute of Neurological Disorders and Stroke (NINDS).

METHODS

One working group composed of ten experts reviewed existing NINDS CDEs and outcome measures, evaluated the need for new elements, and provided recommendations for CMD clinical research. The recommendations were compiled, internally reviewed by the CMD working group, and posted online for external public comment. The CMD working group and the NIH CDE team reviewed the final version before release.

RESULTS

The NINDS CMD CDEs and supporting documents are publicly available on the NINDS CDE website (https://www.commondataelements.ninds.nih.gov/CMD.aspx#tab=Data_Standards). Content areas include demographics, social status, health history, physical examination, diagnostic tests, and guidelines for a variety of specific outcomes and endpoints. The CMD CDE WG selected these documents from existing versions that were generated by other disease area working groups. Some documents were tailored to maximize their suitability for the CMD field.

CONCLUSIONS

Widespread use of CDEs can facilitate CMD clinical research and trial design, data sharing and retrospective analyses. The CDEs that are most relevant to CMD research are like those generated for other NMDs, and CDE documents tailored to CMD are now available to the public. The existence of a single source for these documents facilitates their use in research studies and offers a clear mechanism for the discussion and update of the information as knowledge is gained.

Genome- and Cell-Based Strategies in Therapy of Muscular Dystrophies

Muscular dystrophies are a group of heterogeneous genetic disorders characterized by progressive loss of skeletal muscle mass. Depending on the muscular dystrophy, the muscle weakness varies in degree of severity. The majority of myopathies are due to genetic events leading to a loss of function of key genes involved in muscle function. Although there is until now no curative treatment to stop the progression of most myopathies, a significant number of experimental gene- and cell-based strategies and approaches have been and are being tested in vitro and in animal models, aiming to restore gene function. Genome editing using programmable endonucleases is a powerful tool for modifying target genome sequences and has been extensively used over the last decade to correct in vitro genetic defects of many single-gene diseases. By inducing double-strand breaks (DSBs), the engineered endonucleases specifically target chosen sequences. These DSBs are spontaneously repaired either by homologous recombination in the presence of a sequence template, or by nonhomologous-end joining error prone repair. In this review, we highlight recent developments and challenges for genome-editing based strategies that hold great promise for muscular dystrophies and regenerative medicine.

Strukturelle Hirnfehlbildungen mit Mikrozephalie

Hirnfehlbildungen sind ein häufiger Befund bei Mikrozephalien, ihr Nachweis erhöht die Wahrscheinlichkeit einer genetisch bedingten Grunderkrankung. Werden weitere Zusatzsymptome wie Entwicklungsverzögerung oder Epilepsie beobachtet, sollte frühzeitig eine zerebrale Bildgebung möglichst mittels MRT und neuroradiologischer Beurteilung veranlasst werden. Insbesondere Hinweise auf eine Holoprosenzephalie oder neuronale Migrationsstörungen können die Einleitung zielführender genetischer Untersuchungen bahnen. In diesem Artikel sollen für häufigere Formen syndromaler und nicht-syndromaler Mikrozephalien mit wichtigen neuroradiologischen Leitbefunden wie periventrikulären Heterotopien, Lissenzephalie, Double Cortex, Holoprosenzephalie, pontozerebelläre Hypoplasien und Agenesie oder Hypoplasie des Corpus callosum differenzialdiagnostische Überlegungen und diagnostische Algorithmen vorgestellt werden.

Orthognathic Surgery in Patients With Congenital Myopathies and Congenital Muscular Dystrophies: Case Series and Review of the Literature

PURPOSE

This case series examined preoperative findings and the surgical, anesthetic, and postoperative management of 6 patients with congenital myopathies (CMs) and congenital muscular dystrophies (CMDs) treated at a tertiary medical institution with orthognathic surgery over 15 years to describe pertinent considerations for performing orthognathic surgery in these complex patients.

MATERIALS AND METHODS

According to the institutional review board-approved protocol, chart records were reviewed for all orthognathic surgical patients with a clinical, genetic, or muscle biopsy-proved diagnosis of CM or CMD.

RESULTS

Six patients (5 male, 1 female) qualified, and they were treated by 4 surgeons in the division of oral and maxillofacial surgery from 1992 through 2007. Average age was 19.5 years at the time of orthognathic surgery. Five patients had Class III malocclusions and 1 patient had Class II malocclusion. All 6 patients had apertognathia with lip incompetence. Nasoendotracheal intubation with a difficulty of 0/3 (0=easiest, 3=most difficult) was performed in all cases. Routine induction and maintenance anesthetics, including halogenated agents and nondepolarizing muscle relaxants, were administered without malignant hyperthermia. All 6 patients underwent Le Fort level osteotomies; 4 also had mandibular setback surgery with or without balancing mandibular inferior border osteotomies. Five patients required planned intensive care unit care postoperatively (average, 18.4 days; range, 4 to 65 days). Postoperative respiratory complications resulting in major blood oxygen desaturations occurred in 5 patients; 4 of these patients required reintubation during emergency code response. Five patients required extended postoperative intubation (average, 4.2 days; range, 3 to 6 days) and ventilatory support. Average hospital length of stay was 21.8 days (range, 6 to 75 days). Average postoperative follow-up interval was 29.8 weeks (range, 6 to 128 weeks).

CONCLUSIONS

Patients with CMs or CMDs often have characteristic dentofacial malocclusions that contribute to functional problems with feeding and drooling and psychosocial problems. Orthognathic surgery, usually bimaxillary, can be judiciously considered in these patients; these procedures typically require multidisciplinary pre- and postoperative evaluation and care over lengthy hospital stays with a high risk of respiratory complications that bear consideration in treatment planning.

Analysing regenerative potential in zebrafish models of congenital muscular dystrophy

The congenital muscular dystrophies (CMDs) are a clinically and genetically heterogeneous group of muscle disorders. Clinically hypotonia is present from birth, with progressive muscle weakness and wasting through development. For the most part, CMDs can mechanistically be attributed to failure of basement membrane protein laminin-α2 sufficiently binding with correctly glycosylated α-dystroglycan. The majority of CMDs therefore arise as the result of either a deficiency of laminin-α2 (MDC1A) or hypoglycosylation of α-dystroglycan (dystroglycanopathy). Here we consider whether by filling a regenerative medicine niche, the zebrafish model can address the present challenge of delivering novel therapeutic solutions for CMD. In the first instance the readiness and appropriateness of the zebrafish as a model organism for pioneering regenerative medicine therapies in CMD is analysed, in particular for MDC1A and the dystroglycanopathies. Despite the recent rapid progress made in gene editing technology, these approaches have yet to yield any novel zebrafish models of CMD. Currently the most genetically relevant zebrafish models to the field of CMD, have all been created by N-ethyl-N-nitrosourea (ENU) mutagenesis. Once genetically relevant models have been established the zebrafish has several important facets for investigating the mechanistic cause of CMD, including rapid ex vivo development, optical transparency up to the larval stages of development and relative ease in creating transgenic reporter lines. Together, these tools are well suited for use in live-imaging studies such as in vivo modelling of muscle fibre detachment. Secondly, the zebrafish's contribution to progress in effective treatment of CMD was analysed. Two approaches were identified in which zebrafish could potentially contribute to effective therapies. The first hinges on the augmentation of functional redundancy within the system, such as upregulating alternative laminin chains in the candyfloss fish, a model of MDC1A. Secondly high-throughput small molecule screens not only provide effective therapies, but also an alternative strategy for investigating CMD in zebrafish. In this instance insight into disease mechanism is derived in reverse. Zebrafish models are therefore clearly of critical importance in the advancement of regenerative medicine strategies in CMD. This article is part of a Directed Issue entitled: Regenerative Medicine: The challenge of translation.

Sonoelastography: musculoskeletal applications

All participants for image samplings provided written informed consent. Conventional B-mode ultrasonography (US) has been widely utilized for musculoskeletal problems as a first-line approach because of the advantages of real-time access and the relatively low cost. The biomechanical properties of soft tissues reflect to some degree the pathophysiology of the musculoskeletal disorder. Sonoelastography is an in situ method that can be used to assess the mechanical properties of soft tissue qualitatively and quantitatively through US imaging techniques. Sonoelastography has demonstrated feasibility in the diagnosis of cancers of the breast and liver, and in some preliminary work, in several musculoskeletal disorders. The main types of sonoelastography are compression elastography, shear-wave elastography, and transient elastography. In this article, the current knowledge of sonoelastographic techniques and their use in musculoskeletal imaging will be reviewed.

Cancer risk among patients with hereditary muscular dystrophies: a population-based study in Taiwan, 1997-2009

Muscular dystrophies (MD) comprise a heterogeneous group of hereditary myopathic diseases. In this group, myotonic MD is associated with an increased cancer risk. However, the cancer risk in other types of MD is unclear. To address this gap in knowledge, we assessed data obtained from the Taiwan Health Insurance Program database. A total of 1,272 patients with MD diagnosed between 1997 and 2009 were enrolled. They were followed up for cancer during the same period by record linkage with the cancer certification in Taiwan. Age- and sex-standardized incidence ratios (SIRs) of overall and site-specific cancers were calculated. For congenital and progressive hereditary MD, there were 685 and 505 cases (males: 69.5% and 80.6%), the median ages at diagnosis were 16 and 13 years, and the mean follow-up durations were 7.12 and 5.06 years, respectively. In addition, cancers were developed in 10 patients with congenital MD and 3 patients with progressive hereditary MD. Female MD patients exhibited an increased cancer risk, yielding an SIR of 3.37 [95% confidence interval (CI) = 1.38-8.25] in congenital MD and 2.95 (95% CI = 0.95-9.19) in hereditary progressive MD. Site-specific cancer SIRs were not powered to be significantly different. In conclusion, genetic defects in hereditary MD may increase cancer risks in females and a sex difference should be further investigated.