$Unique_ID{BRK04019} $Pretitle{} $Title{Muscular Dystrophy, Duchenne} $Subject{Muscular Dystrophy, Duchenne Pseudohypertrophic Muscular Dystrophy Childhood Muscular Dystrophy DMD Muscular Dystrophy, Classic X-linked Recessive Progressive Muscular Dystrophy of Childhood Glycerol Kinase Deficiency Muscular Dystrophy, Batten Turner } $Volume{} $Log{} Copyright (C) 1985, 1988, 1989, 1992 National Organization for Rare Disorders, Inc. 37: Muscular Dystrophy, Duchenne ** IMPORTANT ** It is possible that the main title of the article (Muscular Dystrophy, Duchenne) is not the name you expected. Please check the SYNONYMS listing to find the alternate name and disorder subdivisions covered by this article. Synonyms Pseudohypertrophic Muscular Dystrophy Childhood Muscular Dystrophy DMD Muscular Dystrophy, Classic X-linked Recessive Progressive Muscular Dystrophy of Childhood Information on the following diseases can be found in the Related Disorders section of this report: Glycerol Kinase Deficiency Muscular Dystrophy, Batten Turner General Discussion ** REMINDER ** The Information contained in the Rare Disease Database is provided for educational purposes only. It should not be used for diagnostic or treatment purposes. If you wish to obtain more information about this disorder, please contact your personal physician and/or the agencies listed in the "Resources" section of this report. Duchenne Muscular Dystrophy is a rare inherited neuromuscular disorder and one of the most prevalent types of muscular dystrophy. This disorder is characterized by rapid progression of muscle degeneration which occurs early in life. Almost all affected children are male. Symptoms Duchenne Muscular Dystrophy is a rare inherited disorder characterized by progressive muscle weakness. Early symptoms usually begin between the ages of 2 to 5 years. Muscle wasting is initially limited to the shoulder and pelvic areas. Infiltration of fat and connective tissue into the muscles may produce an enlargement (hypertrophy) of the calf muscles in the legs. Within several years Duchenne Muscular Dystrophy affects the muscles of the upper trunk and arms. Eventually all the major muscles are affected. The early symptoms of Duchenne Muscular Dystrophy may include falling, a waddling walk (gait) and awkwardness. Generally these earliest signs are attributed to clumsiness. By the age 3 to 5 years, generalized muscle weakness becomes more obvious. Parents may be falsely encouraged by a seeming improvement between the ages of 3 and 7, but this may be due to natural growth and development. Weakness progresses rapidly after age 8 or 9, resulting in the inability to walk or stand alone. Leg braces may make walking possible for a year or two, but by early adolescence walking becomes impossible. In the late stages of Duchenne Muscular Dystrophy there is a noticeable shortening of muscles and the loss of muscle tissue. This may result in the inability to move the major joints of the body (fixed contractures). There may also be a noticeable increase in the curvature of the spine (scoliosis). Lung capacity may decrease, resulting in an increased susceptibility to respiratory infections. Tests are available to detect muscular dystrophy either before or after birth. The prenatal genetic test determines whether the fetus is carrying the Duchenne Muscular Dystrophy gene. The postnatal test uses antidystrophin antibodies to locate dystrophin in muscle tissue. Dystrophin is a protein normally found in muscles. People with Duchenne Muscular Dystrophy are deficient in dystrophin whereas people with Becker Muscular Dystrophy have a normal amount of dystrophin in the tissue, but the molecule is abnormally small or large. People with Becker Muscular Dystrophy generally have the same symptoms as those with Duchenne Muscular Dystrophy. However, the symptoms of Becker Muscular Dystrophy generally appear later in life than those of Duchenne Muscular Dystrophy, and they do not progress as quickly. Causes Duchenne Muscular Dystrophy is a rare neuromuscular disorder that is inherited as an X-linked recessive trait. The gene that is responsible for this disorder has been identified on the short arm of the X chromosome. Symptoms develop due to a lack of the protein dystrophin in the muscles. Human traits, including the classic genetic diseases, are the product of the interaction of two genes, one received from the father and one from the mother. X-linked recessive disorders are conditions that are coded on the X chromosome. Females have two X chromosomes, but males have one X chromosome and one Y chromosome. Therefore, in females, disease traits on the X chromosome can be masked by the normal gene on the other X chromosome. Since males only have one X chromosome, if they inherit a gene for a disease present on the X, it will be expressed. Men with X-linked disorders transmit the gene to all their daughters, who are carriers, but never to their sons. Women who are carriers of an X-linked disorder have a fifty percent risk of transmitting the carrier condition to their daughters, and a fifty percent risk of transmitting the disease to their sons. Approximately 30 percent of patients with Duchenne Muscular Dystrophy have no family history of the disorder. This can mean that the genetic mutation is new in those families (spontaneous). The disorder is diagnosed by finding a deficiency of dystrophin in the muscles. Affected Population All of the muscular dystrophies combined together affect approximately 40,000 people in the United States. Duchenne Muscular Dystrophy is one of the most prevalent forms of Muscular Dystrophy. This type of Muscular Dystrophy affects males almost exclusively. It is estimated that approximately 1 in every 4,000 newborn males has Duchenne Muscular Dystrophy in the United States. Related Disorders Symptoms of the following disorders can be similar to those of Duchenne Muscular Dystrophy. Comparisons may be useful for a differential diagnosis: Glycerol Kinase Deficiency is a rare inborn error of metabolism that produces adrenal cortical insufficiency and adrenal atrophy. The major characteristics of this disorder are muscular weakness and developmental delays. The muscle atrophy seen in Glycerol Kinase Deficiency is almost indistinguishable from that in Duchenne Muscular Dystrophy. Many patients have muscle wasting and weakness with elevated creatine kinase levels that can be identified through laboratory tests. Batten Turner Muscular Dystrophy is a rare form of muscular dystrophy that is present at birth. The initial symptoms of this disorder in the infant may be a generalized "floppiness" and lack of muscle tone (hypotonia). Later muscular weakness may make the child prone to falling and stumbling. Early motor development and milestone achievements may be minimally delayed. As a rule, walking becomes normal later in life, but physical activities may be hampered. (For more information on this disorder, choose "Batten Turner Muscular Dystrophy" as your search term in the Rare Disease Database). Therapies: Standard Treatment for Duchenne Muscular Dystrophy is symptomatic and supportive. Physical therapy and orthopedic devices can alleviate some of the symptoms of this disorder. Therapies: Investigational The gene that is defective in people with Duchenne Muscular Dystrophy appears to serve as the blueprint for the manufacture of the protein dystrophin in muscle tissue. Symptoms occur when dystrophin is completely absent from the muscles. With this knowledge, scientists are investigating how to replace dystrophin in the body of people with Duchenne Muscular Dystrophy. Scientists are studying the use of the corticosteroid drug, prednisone, as a treatment for Duchenne Muscular Dystrophy. Preliminary results suggest that prednisone improves muscle strength in patients affected by this disorder. It is not yet clear whether prolonged treatment with corticosteroids will be safe and effective since these drugs can have severe side effects. This disease entry is based upon medical information available through October 1992. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder. Resources For more information on Duchenne Muscular Dystrophy, please contact: National Organization for Rare Disorders (NORD) P.O. Box 8923 New Fairfield, CT 06812-1783 (203) 746-6518 Muscular Dystrophy Association, National Office 3561 E. Sunrise Dr. Tucson, AZ 85718 (602) 529-2000 NIH/National Institute of Neurological Disorders & Stroke (NINDS) 9000 Rockville Pike Bethesda, MD 20892 (301) 496-5751 (800) 352-9424 Muscular Dystrophy Group of Great Britain and Northern Ireland Nattrass House 35 Macaulay Road London, England SW4 OQP 01-720-8055 Society for Muscular Dystrophy International P.O. Box 479 Bridgewater, Nova Scotia, Canada B4V 2X6 For Genetic Information and Genetic Counseling Referrals: March of Dimes Birth Defects Foundation 1275 Mamaroneck Avenue White Plains, NY 10605 (914) 428-7100 Alliance of Genetic Support Groups 35 Wisconsin Circle, Suite 440 Chevy Chase, MD 20815 800-336-GENE 301-652-5553 References MENDELIAN INHERITANCE IN MAN, 10th Ed.: Victor A. McKusick, Editor: Johns Hopkins University Press, 1992. Pp. 1916-1922. CECIL TEXTBOOK OF MEDICINE, 19th Ed.: James B. Wyngaarden, and Lloyd H. Smith, Jr., Editors; W.B. Saunders Co., 1990. Pp. 2253-2255. PRINCIPLES OF NEUROLOGY, 4th Ed.; Raymond D. Adams, M.D. and Maurice Victor, M.D., Editors; McGraw-Hill Information Services Company, 1989. Pp. 118-121. RANDOMIZED, DOUBLE-BLIND SIX-MONTH TRIAL OF PREDNISONE IN DUCHENNE'S MUSCULAR DYSTROPHY. J.R. Mendell, et al.; new Eng J of Med (June 15, 1989, issue 320(24)). Pp. 1592-1597.