- Muscular Dystrophy

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MUSCULAR DYSTROPHY

INTRODUCTIO N

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MUSCULAR DYSTROPHY

INTRODUCTIONMuscular dystrophy (abbreviated MD) refers to a group of muscle diseases that weaken the muscles that move the human body. Muscular dystrophies are characterized by progressive skeletal muscle weakness, defects in muscle proteins, and the death of muscle cells and tissue. Nine diseases including Duchenne, Becker, limb girdle, congenital, facioscapulohumeral, myotonic, oculopharyngeal, distal, and Emery-Dreifuss are always classified as muscular dystrophy but there are more than 100 diseases in total with similarities to muscular dystrophy. Most types of MD are multi-system disorders with manifestations in body systems including the heart, gastrointestinal and nervous systems, endocrine glands, skin, eyes and other organs, namely the brain. The condition may also lead to mood swings and learning difficulties. In the 1860s, descriptions of boys who grew progressively weaker, lost the ability to walk, and died at an early age became more prominent in medical journals. In the following decade, French neurologist Guillaume Duchenne gave a comprehensive account of 13 boys with the most common and severe form of the disease (which now carries his name Duchenne muscular dystrophy). It soon became evident that the disease had more than one form, and that these diseases affected males of all ages. Muscular dystrophy (MD) is a genetic (inherited) condition that over time gradually causes the muscles to weaken. This leads to an increasing level of disability.

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There are several different types of MD, with different symptoms and patterns of progression. Not all types of MD cause severe disability, but there is currently no cure for the condition. MD is caused by mutations (cellular changes) in the genes that are responsible for the structure and functioning of a persons muscles. The mutations can occur spontaneously, but they are normally inherited from a persons parents. The mutations cause changes in the muscle fibres, which interferes with the muscles ability to function. Over time, this causes increasing disability. Muscular dystrophies are a group of inherited muscle disorders in which one or more genes needed for normal muscle function are defective, leading to muscle weakness (see Symptoms and Diagnosis of Musculoskeletal Disorders: Weakness) of varying severity. Other inherited muscle disorders include congenital myopathies, periodic paralysis, and glycogen storage diseases. Glycogen storage diseases are a group of rare inherited disorders in which muscles cannot metabolize sugars normally (see Hereditary Metabolic Disorders: Glycogen Storage Diseases), so they build up large stores of glycogen (a starch that is formed from sugars). Muscular dystrophy is the term used to describe a group of diseases of the muscles. With muscular dystrophy the muscles become weak and can waste away.There are over 20 different kinds of muscular dystrophies. The number of people affected by muscular dystrophy depends on the specific type. For example,approximately one child in 4,000 will have Spinal Muscular Atrophy.3|Page

MUSCULAR DYSTROPHY

Approximately one in 3,000 will have Duchenne Muscular Dystrophy. The different types of muscular dystrophy have different causes. Some have genetic causes. A virus or illness causes some. Others have unknown causes.

To diagnose muscular dystrophy a doctor will take a detailed history, perform a thorough physical examination, and conduct specific tests. One of these tests is an electromyogram (EMG), which measuresthe electrical activity of the muscles.

If a diagnosis cannot be made based on these tests, a muscle biopsy is oftenThese tests usually give the diagnosis in about 80% of the patients. However, even with new tests approximately 15%-20% of patients will go undiagnosed.

Some of the health problems that people with muscle diseases can experience are problems with breathing and/or heart problems. Many patients can develop curvature of the spine (scoliosis) or muscle contractions leading to the need for surgery.

The treatment depends upon the specific cause of muscle weakness. However, physical therapy and occupational therapy are often used. In some cases a person with a muscle disease will get worse over time, and may have a shorter life expectancy than someone without the disease. However, some of the muscle diseases do not affect life expectancy at all.

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DEFINITION

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DEFINITION:One of a group of genetic diseases characterized by progressive weakness and degeneration of the skeletal or voluntary muscles which control movement. The muscles of the heart and some other involuntary muscles are also affected in some forms of muscular dystrophy, and a few forms involve other organs as well. Guillaume-Benjamin-Amand Duchenne, 1987 Inherited disease that causes progressive weakness in the skeletal (and occasionally heart) muscle. Muscle tissue degenerates and regenerates randomly and is replaced by scar tissue and fat. Britannica Concise Encyclopaedia, 1999 Muscular dystrophies (MD) are inherited disorders characterized by progressive weakness and degeneration of the skeletal or voluntary muscles which control movement, without a central or peripheral nerve abnormality. The muscles of the heart and other involuntary muscles are also affected in some forms of MD, and a few forms involve other organs as well. Neurological Disorder Journals, 2000

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REVIEW OF LITERATURE

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Lunt and Harper et al (1991) concluded that there is a dominantly inherited scapulohumeral or scapuloperoneal syndrome genetically distinct from FSHD that does not have facial weakness as a feature. Many cases (as much as 25%) may represent new, ex-novo mutations. Alan E H Emery et al 1954 stated that muscular dystrophies are a group of genetic diseases that severely affect children and adults. For sufferers and their family, the illness presents enormous physical and psychological challenges.

C. Jimenez-Mallebrera, S. C. Brown, C. A. Sewry and F. Muntoni et al December 2004 congenital muscular dystrophies are a clinically and genetically heterogeneous group of neuromuscular disorders. Each form has a characteristic phenotype, but there is overlap between some entities and their classification is based on a combination of clinical features and the primary or secondary protein defect.

Josef Finsterer et al 17 July 2006 becomes definite in all patients with MD, BMD, and MMP, but progresses markedly only in BMD patients within 10 years. MD, BMD, or MMP patients should be cardiologically investigated as soon as the neurological diagnosis is established and treated if CI becomes symptomatic, or in case of severe ECG or echocardiographic abnormalities.

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Stamulumab et al 2005/2006 trial was completed by Wyeth in Collegeville, PA. As of April 2007, the results of the study have not yet been made public, but it is one of the few known drugs in development for the treatment for muscular dystrophy. Myostatin is a protein that inhibits the growth of muscle tissue, MYO029 is a recombinant human antibody designed to bind and inhibit the activity of myostatin. Abu-Baker A, Rouleau GA et al 2003 made experiments and finally made a conculsion that Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disorder characterized by progressive eyelid drooping, swallowing difficulties and proximal limb weakness. OPMD is caused by a small expansion of a short polyalanine tract in the poly (A) binding protein nuclear 1 protein (PABPN1). QH Leyten et al 1996 Congenital muscular dystrophy (CMD) is a condition in which there are already at birth, marked hypotonia, generalized muscle weakness and frequently multiple contractures. CMD has recently been classified into four categories: CMD I, the classical or pure CMD without severe impairment of intellectual development; CMD II, the Fukuyama type CMD with muscle and structural brain abnormalities. B. G. M. van Engelen et al 16 December 1999 Central nervous system (CNS) characteristics were examined in seventeen patients with autosomal recessive classic or pure congenital muscular dystrophy (CMD). In three patients, neuroradiological examination (CT/MRI) indicated hypodense white matter areas. Two out of these three patients had epilepsy (seizures and epileptic discharges on their EEG)

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F. J. M. Gabrels et al 19 March 1999 conducted an experiment on congenital muscular dystrophy (CMD) in a 13-year-old girl with early manifestation of muscle weakness and hypotonia, severe contractures, bulbar syndrome, progressive external ophtalmoplegia, and white matter changes on magnetic resonance imaging (MRI) of the brain, but no mental defect. Serum creatine kinase (CK) level was normal. Jennifer E. Morgan et al 26 August 2002 observed that Steroids represent the only pharmacological palliative treatment for Duchenne muscular dystrophy. However, they do have side effects and despite a large number of published studies showing their efficacy, they are still not universally used. This is largely due to the lack of functional outcome and quality of life measures in most of the published studies and suggests that further trials might be required to answer some of the still unclear aspects of their role. Sara T Winokur et al 19 November 2002 reported that the myoblasts suggests that aberrant gene expression occurs early in facioscapulohumeral muscular dystrophy muscle development. In order to test this hypothesis, global gene expression profiling and in vitro characterization of facioscapulohumeral muscular