Spotlight on Emery-Dreifuss muscular dystrophy

In this article, Dr. Howard Worman of Columbia University discusses Emery-Dreifuss muscular dystrophy, a syndrome classically characterized by (1) slowly progressive muscle weakness and wasting in a scapulo-humeroperoneal distribution; (2) early contractures of the elbows, ankles, and posterior neck; and (3) dilated cardiomyopathy with conduction defects. Originally described as an X-linked disorder, Emery-Dreifuss muscular dystrophy-like phenotypes can arise from mutations in both autosomal and X chromosome genes including those encoding emerin and A-type lamins as well as in less frequent cases those encoding nesprin1, nesprin2, SUN1, SUN2, four-and-a-half-LIM protein 1, LUMA, and lamina-associated polypeptide 1. Although the skeletal muscle involvement can vary as a result of mutations in these genes, cardiomyopathy is the most prevalent and potentially life-threatening feature.

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Spotlight on Reducing body myopathy

Dr. Joseph Siebert discusses reducing body myopathy, a rare condition with early infant to adult onset characterized by abnormal inclusions in muscle fibers that are highlighted by special stains. A protein, FHL1, has been identified in these inclusions by proteomic techniques, and mutations in the corresponding gene identified in both sporadic and familial cases. Although the pathophysiology remains poorly understood, inclusions may be involved in processing and assembling ribosomes. Thus, their activity seems to be related intimately to muscle mass and function and leads to progressive muscle weakness, with wasting, and eventual death due to respiratory failure.

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MedLink Neurology authors are always at work to bring you broad and up-to-date coverage of neurology topics. We are pleased to highlight clinical summaries that have been recently added or updated and to introduce the authors who write these authoritative articles. We hope you enjoy these overviews and appreciate the contributions of our more than 450 authors who keep MedLink Neurology the premier information resource for neurologists.

Spotlight on Emery-Dreifuss muscular dystrophy

Emery-Dreifuss muscular dystrophy is a phenotype of (1) slowly progressive muscle weakness and wasting in a scapulo-humeroperoneal distribution; (2) early contractures of the elbows, ankles, and posterior neck; and (3) dilated cardiomyopathy with conduction defects. Originally described as an X-linked disorder, the Emery-Dreifuss muscular dystrophy phenotype can arise from mutations in both autosomal and X chromosome genes, including those encoding emerin, A-type lamins, nesprin1, nesprin2, four-and-a-half-LIM protein 1, and LUMA. Cardiomyopathy is the life-threatening feature that can occur with variable or no skeletal muscle involvement as a result of mutations in these genes. In this clinical summary, Dr. Howard Worman of Columbia University discusses the manifestations, etiology, and diagnosis of Emery-Dreifuss muscular dystrophy.

To view the complete clinical summary, click here.

MedLink Neurology authors are always at work to bring you broad and up-to-date coverage of neurology topics. We are pleased to highlight clinical summaries that have been recently added or updated and to introduce the authors who write these authoritative articles. We hope you enjoy these overviews and appreciate the contributions of our more than 450 authors who keep MedLink Neurology the premier information resource for neurologists.

Spotlight on Spinal muscular atrophy

In this clinical summary, Drs. Barry Russman and Erika Hedderick of Oregon Health Science University discuss spinal muscular atrophy, which presents with proximal muscle weakness of the upper and lower extremities, the latter being weaker than the former, at least initially. The condition is caused by a deletion of exon 7 on chromosome 5. Other spinal muscular atrophies exist that are not linked to 5Q. Current classification is based on clinical criteria, including age of onset and maximum function attained. The diagnosis is established by a DNA test for the SMN gene. Further testing, including EMG and muscle biopsy are unnecessary. To date, treatment is symptomatic; therapeutic trials have failed to reveal a specific cure for this condition.

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MedLink Neurology authors are always at work to bring you broad and up-to-date coverage of neurology topics. We are pleased to highlight clinical summaries that have been recently added or updated and to introduce the authors who write these authoritative articles. We hope you enjoy these overviews and appreciate the contributions of our more than 450 authors who keep MedLink Neurology the premier information resource for neurologists.