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$Unique_ID{BRK04018}
$Pretitle{}
$Title{Muscular Dystrophy, Becker}
$Subject{Muscular Dystrophy, Becker BMD Progressive Tardive Muscular Dystrophy
Benign Juvenile Muscular Dystrophy Duchenne Muscular Dystrophy Leyden-Moebius
Muscular Dystrophy Gower's Muscular Dystrophy }
$Volume{}
$Log{}
Copyright (C) 1989 National Organization for Rare Disorders, Inc.
598:
Muscular Dystrophy, Becker
** IMPORTANT **
It is possible that the main title of the article (Becker Muscular
Dystrophy) is not the name you expected. Please check the SYNONYM listing to
find the alternate names and disorder subdivisions covered by this article.
Synonyms
BMD
Progressive Tardive Muscular Dystrophy
Benign Juvenile Muscular Dystrophy
Information on the following diseases can be found in the Related
Disorders section of this report:
Duchenne Muscular Dystrophy
Leyden-Moebius Muscular Dystrophy
Gower's Muscular Dystrophy
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.
Becker Muscular Dystrophy is a rare inherited muscle wasting disease
usually beginning during the second or third decade of life. This slowly
progressive disorder affects males almost exclusively. Muscles of the hips
and shoulders are weakened, walking abnormalities develop, and mild mental
retardation may be present. Eventually, other more severe symptoms may
involve the heart and lungs.
Symptoms
Becker Muscular Dystrophy (BMD) is characterized by slowly progressive
weakness of the hip and shoulder muscles. These muscles tend to be firm and
rubbery. Deep tendon reflexes may be lost early in the course of this
disorder. Ability to walk is affected, and mild mental retardation may be
present. Joint contractures, curvature of the spine (scoliosis), restrictive
lung disease, and in rare cases heart problems, can develop with time.
Female carriers of BMD are usually not affected, although most have an
elevated creatine phosphokinase (CPK) concentration in the blood system.
Causes
Becker Muscular Dystrophy (BMD) is inherited as an X-linked recessive trait.
(Human traits including the classic genetic diseases, are the product of the
interaction of two genes for that condition, one received from the father and
one from the mother. X-linked recessive disorders are conditions which 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.)
Scientists recently discovered the specific protein deficiency that causes
symptoms of this disorder. The protein is known as dystrophin. Symptoms
result when the body produces either too little or an abnormal form of this
protein.
About 30% of Muscular Dystrophy cases have no history of the disease in
their family. It was difficult to diagnose these people until a test to
detect dystrophin in muscles was developed. The cause of spontaneous (non-
genetic) cases of Muscular Dystrophy is still unknown.
Affected Population
Becker Muscular Dystrophy (BMD) affects males almost exclusively. Females
are usually not affected, although they may carry the genetic trait. This
disorder occurs in approximately one in 30,000 live births.
Related Disorders
Symptoms of the following disorders can be similar to those of Becker
Muscular Dystrophy (BMD). Comparisons may be useful for a differential
diagnosis:
Duchenne Muscular Dystrophy (DMD) is the most rapidly progressive form of
muscular dystrophy and one of the most common. This muscle-wasting disorder,
which affects boys almost exclusively, typically begins between the ages of
two and five and progresses rapidly. The protein known as dystrophin which
causes symptoms of DMD is the same as that of Becker Muscular Dystrophy
(BMD). However, BMD patients produce too little or an abnormal form of
dystrophin whereas DMD patients do not produce any of this protein.
Leyden-Moebius Muscular Dystrophy (Limb-Girdle Muscular Dystrophy) is a
progressive disorder that usually begins during pre-adolescence. The pelvic
area is the most severely affected with weakness and muscular deterioration.
Muscles of the face, shoulders and arms are also affected. This disorder is
inherited by a different mode of transmission than that of Becker Muscular
Dystrophy.
Gower's Muscular Dystrophy is a rare, slowly progressive weakness that
begins in the hands and feet, then extends to other nearby areas of the body
causing only moderate weakness. This disorder usually begins during
adulthood.
(For more information on these disorders, choose "muscular dystrophy" as
your search term in the Rare Disease Database.)
Therapies: Standard
At this time, no specific treatment exists for Becker Muscular Dystrophy
(BMD). However, exercise combined with physical therapy and orthopedic
devices may benefit most patients. Genetic counseling may be of benefit for
patients and their families because genetic tests are available to identify
this disorder. Other treatment is symptomatic and supportive.
Tests are available to detect Muscular Dystrophy prenatally and
postnatally. The prenatal test is a genetic test to learn if a person is
carrying the MD gene. Postnatal tests use antidystrophin antibodies which
allow detection of dystrophin in muscle tissue. People with Duchenne
Muscular Dystrophy are deficient in dystrophin, while those with Becker
Muscular Dystrophy have a dystrophin molecule that is either smaller or
larger than normal, but present in normal quantities in the muscles.
Therapies: Investigational
The gene abnormality which causes Becker Muscular Dystrophy (BMD) and the
protein deficiency linked to symptoms have both been identified. Researchers
hope to learn how they may alter this process, thus curing or treating this
disorder in the future.
This disease entry is based upon medical information available through
August 1989. 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 Becker 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
3300 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 0QP
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
PREFERENTIAL DELETION OF EXONS IN DUCHENNE AND BECKER MUSCULAR
DYSTROPHIES: S.M. Forrest, et al.; Nature (October 15-21, 1987, issue 329
(6140)). Pp. 638-640.
EVALUATION OF CARRIER DETECTION RATES FOR DUCHENNE AND BECKER MUSCULAR
DYSTROPHIES USING SERUM CREATINE-KINASE (CK) AND PYRUVATE-KINASE (PK) THROUGH
DISCRIMINANT ANALYSIS: M. Zatz, et al.; Am J Med Genet (October 1986, issue
25(2)). Pp. 219-230.
MENDELIAN INHERITANCE IN MAN, 7th ed.: Victor A. McKusick; Johns Hopkins
University Press, 1986. Pp. 1427-1428.
INTERNAL MEDICINE, 2nd Ed.: Jay H. Stein, ed.-in-chief; Little, Brown
and Co., 1987. Pp. 2238-2239.