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$Unique_ID{BRK03690}
$Pretitle{}
$Title{Dystrophy, Myotonic}
$Subject{Dystrophy Myotonic Steinert Disease Curschmann-Batten-Steinert
Syndrome Myotonia Atrophica Klinefelter Syndrome Myotonia Congenita Thomsen's
Disease Turner's Syndrome Noonan's Syndrome}
$Volume{}
$Log{}
Copyright (C) 1987, 1988, 1990 National Organization for Rare Disorders, Inc.
357:
Dystrophy, Myotonic
** IMPORTANT **
It is possible the main title of the article (Myotonic Dystrophy) is not
the name you expected. Please check the SYNONYMS listing to find the
alternate names, disorder subdivisions, and related disorders covered by this
article.
Synonyms
Steinert Disease
Curschmann-Batten-Steinert Syndrome
Myotonia Atrophica
Information on the following diseases can be found in the Related
Disorders section of this report:
Klinefelter Syndrome
Myotonia Congenita, also known as Thomsen's Disease
Turner's Syndrome
Noonan's Syndrome
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.
Myotonic Dystrophy is an inherited disorder involving the muscles,
vision, and endocrine glands. It can cause mental deficiency and loss of
hair. Onset of this rare disorder commonly occurs during young adulthood.
However, it can occur at any age and is extremely variable in degree of
severity.
Symptoms
Myotonic Dystrophy usually begins during young adulthood and is marked
initially by an inability to relax muscles after contraction. Loss of
muscle strength, mental deficiency, cataracts, reduction of testicular
function, and frontal baldness are also symptomatic of this disorder.
Tripping, falling, difficulty in moving the neck, lack of facial expression
and a nasal sounding voice are among many symptoms that can result from
selective muscle involvement.
Following is a list of symptoms that may occur as a result of selective
muscle involvement:
1) Drooping eyelids
2) Furrowed forehead
3) Tipping the head when attempting to see straight
4) Inability to let go after shaking hands
5) Lack of ability to relax muscles after tensing (particularly in the
forearms)
6) Weakness of fingers and thumb
7) Muscular atrophy (particularly in the head and neck area)
8) Weakness of the lifting muscles
9) Weakness of the tongue
10) Weakness of the arm and leg muscles
Testicular atrophy, impotence, possibly development of enlarged male
breasts (gynecomastia), and some features of Klinefelter Syndrome are also
symptomatic of Myotonic Dystrophy in males. (For more information, choose
"Klinefelter" as your search term in the Rare Disease Database).
Causes
Myotonic Dystrophy is inherited as a dominant trait with incomplete
penetrance. (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. In dominant disorders, a single copy of
the disease gene (received from either the mother or father) will be
expressed "dominating" the normal gene and resulting in appearance of the
disease. The risk of transmitting the disorder from affected parent to
offspring is 50% for each pregnancy regardless of the sex of the resulting
child.) Incomplete penetrance of a gene means that all characteristics of a
particular trait may not be manifested in all those who inherit the defective
gene.
Scientists recently isolated a gene on chromosome 19 that they believe
is responsible for Myotonic Dystrophy. A method using genetic markers called
"fragment polymorphisms" has been developed to predict with 90% certainty
which individuals are at risk for developing Myotonic Dystrophy.
Affected Population
Myotonic Dystrophy is a rare disorder that affects males and females in equal
numbers. Onset usually occurs in children or young adults.
Related Disorders
Klinefelter Syndrome, which is characterized by the presence of one or more
extra X-chromosomes, is the most frequent cause of primary hypogonadism.
Hypogonadism is a condition in which abnormally decreased functional activity
of the gonads can result in retardation of growth and sexual development.
Klinefelter Syndrome becomes evident only after puberty with evidence of
infertility and/or testicular deficiency (eunuchoidism) of varying degrees.
Abnormally large mammary glands can occur in this disorder.
Myotonia Congenita or Thomsen's Disease is a rare inherited disorder that
begins early in life and involves the entire muscle system. Difficulty in
initiating movement combined with slowness of relaxation are the chief
symptoms. Muscle stiffness of the entire body may also occur with this
generally nonprogressive disorder. (For more information, choose "Thomsen"
as your search term in the Rare Disease Database.)
Turner's Syndrome is a genetic disorder affecting females which is
characterized by lack of sexual development, small stature, possible mental
retardation, a webbed neck, heart defects, and various other congenital
abnormalities. Individuals have an XO karotype; i.e., they have neither the
second X chromosome that characterizes females nor the Y chromosome of males.
They have a female appearance. (For more information on this disorder,
choose "Turner" as your search term in the Rare Disease Database.)
Noonan's Syndrome is related to Turner's Syndrome, but it affects males
exclusively.
Therapies: Standard
The muscle weakness caused by Myotonic Dystrophy does not seem to respond to
physical therapy, but active and passive exercises may still be helpful.
Agencies which provide services to handicapped people and their families may
be of benefit. Genetic counseling can be useful for families with this
disorder. Other treatment is symptomatic and supportive.
Treatment with anti-arrythmic and anti-convulsant drugs may be of
therapeutic benefit, but cannot halt the progress of this disorder. Careful
administration of these drugs is essential to obtain results without
excessive side effects.
Therapies: Investigational
At the present time, a study is being conducted on the effectiveness of the
drugs tocainide (Xylotocan) and nifedipine as treatments for Myotonic
Dystrophy. Selenium and Vitamin E are also being tested and may be helpful
in increasing muscle strength and improvement of some other symptoms of this
disorder. Overdoses of selenium and Vitamin E can be harmful (toxic), so
treatment must be carefully monitored by a physician.
Researchers announced in the February 8, 1990 issue of the journal
"Science" that they believe the gene for Myotonic Dystrophy is on chromosome
19. More research is necessary to determine whether a genetic test can be
developed as a result of this research.
This disease entry is based upon medical information available through
April 1990. 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 Myotonic 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
The National Arthritis and Musculoskeletal and Skin Diseases Information
Clearinghouse
Box AMS
Bethesda, MD 20892
(301) 495-4484
For information on genetics and genetic counseling referrals, please
contact:
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
SELENIUM THERAPY OF MYOTONIC DYSTROPHY: G. Orndahl, et. al.; Acta Med Scand,
(1983, issue 213(3)). Pp. 237-239.
THE PROBLEM OF DIAGNOSIS AND THERAPY OF MYOTONIC DYSTROPHY: F.
Reisecker; Wien Med Wochenschr (June 30, 1983, issue 133(12)). Pp. 319-321.
NIFEDIPINE IN THE TREATMENT OF MYOTONIA IN MYOTONIC DYSTROPHY. R. Grant, et
al.; J NEUROL NEUROSURG PSYCHIATRY (February 1987, issue 50(2)). Pp. 199-206.
MYOTONIC DYSTROPHY TREATED WITH SELENIUM AND VITAMIN E. G. orndahl, et
al.; ACTA MED SCAN (1986, issue 219 (4)). Pp. 407-414.
ANTIMYOTONIC THERAPY WITH TOCAINIDE UNDER ECG CONTROL IN THE MYOTINIC
DYSTROPHY OF CURSCHMANN-STEINERT. U. Mielke, et al.; J NEUROL (1985, issue
232 (5)). Pp. 271-274.