Relatively benign congenital muscular dystrophy usually beginning in late childhood or adolescence and characterized clinically by early muscle contractures leading to toe-walking, rigid spine, calf hypertrophy, and loss of muscular movements mainly in the shoulders, upper arms and the lower legs. This medical condition also affects the cardiac muscles and conduction pathways. This medical condition is often defined as a triad of muscular atrophy, upper arms and lower legs contractures, and cardiomyopathy.
Scapuloilioperoneal Atrophy Cardiomyopathy Syndrome.
The types of Emery-Dreifuss muscular dystrophy are distinguished by their pattern of inheritance:
X-Linked Emery-Dreifuss Muscular Dystrophy: Results from an alteration in the EMD gene and the protein emerin. Besides involvement of the somatic musculature, it affects the cardiac muscle and present variable degree of mental retardation.
Autosomal Dominant Emery-Dreifuss Muscular Dystrophy: Individuals experience heart problems with severe muscle atrophy, contractures of the arms and lower legs, especially the Achilles tendon. It is a rarer form of the disease.
Autosomal Recessive Emery-Dreifuss Muscular Dystrophy: Characterized by cardiac involvement, cardiomyopathy, dysrhythmias (eg, severe bradycardia), and severe muscle contractures. Individuals who acquire EDMD via the autosomal recessive route have an incidence of 1 in 300,000.
This syndrome was named after Alan Eglin Heathcote Emery (b. 1928), a British Medical Geneticist, who worked as a foundation professor of human genetics at the University of Edinburgh, and Fritz E. Dreifuss (1926-1997), a German-born New Zealand educated in medicine, who became a renown American Neurologist and subspecialist in the study of epilepsy at the University of Virginia in Charlottesville, Virginia, USA, in 1966. Dr Emery also identified the defective protein involved in this muscular dystrophy, which was named “emerin.”
The overall incidence of EDMD is not known. Previous studies estimated EDMD to be the third most prevalent muscular dystrophy within a group of dystrophinopathies including Duchenne muscular dystrophy and Becker muscular dystrophy, both reported as the two most prevalent. More recently, the prevalence of EDMD was estimated at 0.13:100,000 to 0.2:100,000. The autosomal recessive form has an estimated incidence in the general population approximately 1:300,000. The prevalence of the X-linked form (males only) is estimated at 1:100,000. The autosomal dominant form is much less frequent. The estimated prevalence is approximately 0.13:100,000 to 0.2:100,000 in the general population.
Mutations in the EMD, LMNA, and several suspected genes (SYNE1, SYNE2, FHL1, and TMEM43) have been suggested to cause the various types of Emery-Dreifuss muscular dystrophy. The EMD and LMNA genes are proteins responsible for the making of the components generating the nuclear envelope, surrounding the nucleus in myocyte cells. Amongst the seven described variant genetic types of EDMD, two are well defined based on the inheritance pattern and the protein defect involved, ie, emerin and lamin. They ...