Neuromuscular disorders
Ashley W. Blom, David Warwick, Michael R. Whitehouse in Apley and Solomon’s System of Orthopaedics and Trauma, 2017
The muscular dystrophies are a group of over 50 rare inherited disorders characterized by progressive muscle weakness and wasting. Pathological changes include malformation of muscle fibres, death of musde cells and replacement of muscle by fibrous tissue and fat. Historically, they have been grouped according to their various inheritance patterns, age of onset, distribution of affected musculature and severity of the muscle weakness. The following are those most likely to be encountered in orthopaedic practice: Duchenne muscular dystrophy (DMD) — a severe, generalized sex-linked disorder affecting only boys in early childhood.Becker muscular dystrophy — is similar to DMD but less severe, starts somewhat later and progresses more slowly.Limb girdle dystrophies — a mixed group, usually of autosomal recessive inheritance, with more localized changes, affecting boys and girls in later childhood.Facioscapulohumeral dystrophy — an autosomal dominant condition of variable severity, usually appearing in early adulthood.
Diseases of Muscle and the Neuromuscular Junction
John W. Scadding, Nicholas A. Losseff in Clinical Neurology, 2011
Duchenne and Becker muscular dystrophies are X-linked genetic disorders and are associated with mutations in the dystrophin gene at the Xp21 locus and are therefore called the ‘dystrophinopathies’. They are usually associated with a reduction or loss of expression of dystrophin at the sarcolemma. Duchenne muscular dystrophy (DMD) is the most common of the dystrophies with an incidence of approximately 1:3500 live male births and a prevalence of approximately 6:100 000 total male population. Becker muscular dystrophy (BMD) is less common at approximately 1:18 000 live male births and a prevalence of 2:100 000 total male population. DMD is usually associated with a complete loss of dystrophin and a severe phenotype, whereas BMD is associated with a partial reduction in dystrophin and a milder phenotype.
Muscular dystrophy and arthritis
Michael Horvat, Ronald V. Croce, Caterina Pesce, Ashley Fallaize in Developmental and Adapted Physical Education, 2019
Becker muscular dystrophy is similar to Duchenne muscular dystrophy but progresses more slowly and has a later onset, generally around 10 to 15 years of age. A greater percentage of the children are males, and the disease is sex linked from a recessive X-linked chromosome caused by reduced amounts of dystrophin (NINDS, 2013). Symptoms are similar to those of Duchenne muscular dystrophy. Children demonstrate a prolonged ambulatory capacity until 16 years or later, less severe contractures of the ankle and foot, and nonprogressive scoliosis and skeletal deformities (Bar-Or, 1983). Intellectual impairment generally is not evident in Becker muscular dystrophy, although children may demonstrate varying learning disabilities (MDA, 2018).
Application of the International Classification of Functioning, Disability and Health system to symptoms of the Duchenne and Becker muscular dystrophies
Published in Disability and Rehabilitation, 2018
Kristin M. Conway, Emma Ciafaloni, Dennis Matthews, Chris Westfield, Kathy James, Pangaja Paramsothy, Paul A. Romitti
Duchenne and Becker muscular dystrophies, herein referred to as dystrophinopathies, are X-linked recessive genetic diseases that affect the production of dystrophin [1]. Disease progression affects multiple systems with deterioration of pulmonary, cardiac, and orthopedic function [2]. Severity of disease progression can occur along a spectrum. Duchenne muscular dystrophy is the more severe phenotype with earlier onset of initial motor symptoms (typically before the 5th birthday) and loss of ambulation (typically before the 12th birthday), and progressive deterioration in cardiac and pulmonary function. Becker muscular dystrophy is less severe in phenotypic expression with later onset of initial motor symptoms and loss of ambulation (typically after the 16th birthday), and less severe deterioration in other body systems. The severity and progressive nature of dystrophinopathies can have considerable impact on a patient's participation in activities across multiple life domains [3]. Educational attainment rarely goes beyond secondary school and employment opportunities may be unavailable due to the need for assistance with activities of daily living, reduced physical accessibility, and the lack of assistive technology. Social relationships can also be affected due to the physical limitations imposed by reduced mobility over the lifespan.
Developments in reading frame restoring therapy approaches for Duchenne muscular dystrophy
Published in Expert Opinion on Biological Therapy, 2021
Anne-Fleur E. Schneider, Annemieke Aartsma-Rus
The disease is caused by lack of dystrophin, a protein that provides stability to skeletal muscle fibers by linking the F-actin cytoskeleton to the extracellular matrix [5,6]. This is caused by mutations in the X-chromosomal DMD gene that disrupt the reading frame or cause premature stop codons. Consequently, dystrophin protein translation is prematurely truncated, and the linker function is lost. By contrast, mutations that maintain the open reading frame, generally allow the production of internally deleted dystrophin, that can still fulfill their linker function [7]. These partially functional dystrophins are found in Becker muscular dystrophy (BMD), a muscle-wasting disease that is milder compared to DMD, with a later onset of symptoms and a slower disease progression [1].
Ophthalmological Manifestations of Hereditary Myopathies
Published in Journal of Binocular Vision and Ocular Motility, 2022
Marta Saint-Gerons, Miguel Angel Rubio, Gemma Aznar, Ana Matheu
Duchenne muscular dystrophy (DMD) is a severe X-linked recessive disorder caused by the lack of functional dystrophin protein.70 DMD causes progressive muscle weakness, appears at the age of 2–3 years old, and leads to death in the third decade.71 Becker muscular dystrophy is generally milder than DMD. Multiple isoforms of dystrophin are expressed in the central nervous system including the retinal layers.71 Dystrophin may play a role in retinal neurotransmission. Duchenne muscular dystrophy has not traditionally been included as retinal disease, and patients do not refer to any visual symptoms.72 However, abnormal scotopic electroretinograms (ERGs) were reported to be more frequent in DMD and Becker muscular dystrophy.73 Corticosteroids are a standard treatment for DMD, but side effects of corticosteroids such as cataracts or ocular hypertension are uncommon.74
Related Knowledge Centers
- Dystrophin
- Mutation
- Protein
- Pelvis
- Duchenne Muscular Dystrophy
- X-Linked Recessive Inheritance
- Dystrophinopathy
- Gene
- Wasting
- Fat