$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.