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Neurological Disease
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
In Duchenne muscular dystrophy, most patients use wheelchairs by their teens and die in their twenties. Becker muscular dystrophy is much less severe, and most patients die with their disease rather than because of it.
Miscellaneous Topics
Published in Nirmal Raj Gopinathan, Clinical Orthopedic Examination of a Child, 2021
Prateek Behera, Karthick Rangasamy, Nirmal Raj Gopinathan
Muscular dystrophies are rare genetic disorders seen in children.2 Myopathies can be of genetic origin, or they can be secondary to inflammatory, endocrinological, nutritional, and drug-induced causes. The muscular dystrophies that are encountered in clinical practice are Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), and congenital muscular dystrophy (CMD). Of these, DMD and BMD are seen in males (X-linked inheritance). DMD is the most common hereditary neuromuscular disease affecting all races and ethnic groups.2 From the perspective of clinical presentation, DMD and BMD appear in preschool children. While a child with DMD tends to become bedridden by 10–12 years, those with BMD tend to be ambulatory even into their adulthood. Parents consult a physician with complaints regarding their child’s weakness, inability to walk in a previously walking child, frequent falls, difficulty in climbing stairs, and abnormal swelling of the calf musculature.
Genetics and metabolic disorders
Published in Jagdish M. Gupta, John Beveridge, MCQs in Paediatrics, 2020
Jagdish M. Gupta, John Beveridge
In A the carrier mother can only run the risk of producing a second affected child if her new partner is also a carrier. An incidence of 1 in 40000 implies a carrier rate of 1 in 100 in the general population. Therefore the risk for future affected offspring is 1 in 400. For a mother with a balanced reciprocal translocation who has had multiple miscarriages the risk of future abnormal offspring is approximately 10%, though the precise risk is different for each specific translocation. Becker muscular dystrophy is X-linked recessive which means the husband is not a carrier, and he cannot pass on the mutation. Risk in D is much less than 1%. The risk to any offspring of a parent affected with bilateral retinoblastoma is about 40%.
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
Common therapeutic advances for Duchenne muscular dystrophy (DMD)
Published in International Journal of Neuroscience, 2021
Arash Salmaninejad, Yousef Jafari Abarghan, Saeed Bozorg Qomi, Hadi Bayat, Meysam Yousefi, Sara Azhdari, Samaneh Talebi, Majid Mojarrad
Duchenne muscular dystrophy (DMD) is the most prominent neuromuscular disorders that affecting about 1 in 5000 male live births and caused by gross deletions or duplications (70% of cases) and point mutations (30% of cases) in X-linked DMD gene. The product of the DMD gene is a cytoskeletal protein that functions as a linker between the dystrophin-associated protein complex (DAPC) and intracellular cytoskeleton γ-actin [1]. Generally, DMD emanates from genetic frame-shift mutations that result in abnormal and truncated product. On the other hand, Becker muscular dystrophy (BMD), a milder and slowly progressing form of this X-linked recessive muscular disorder, usually arise from the mutations that cause a shorter, lower molecular weight but partially functional of the gene product. DMD patients typically represent increasing weakness, growing skeletal muscle wasting leading to wheelchair dependency by the age of 10, a later-onset cardiomyopathy and finally untimely death during second to fourth decade of life [2]. This gene and its products were identified during the mid-nineteenth century. Chromosomal locus of the DMD gene is identified by two independent approaches, first take advantage of the X/autosome translocation and also take advantage of a contiguous gene deletion syndrome in patient BB [3].
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].