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$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.