Myotonic dystrophy type 1

Información en español Title

Other Names:

Dystrophia myotonica type 1; DM1; Steinert disease; Dystrophia myotonica type 1; DM1; Steinert disease; Steinert myotonic dystrophy; Steinert's disease See More

Categories:

Congenital and Genetic Diseases; Endocrine Diseases; Eye diseases; Congenital and Genetic Diseases; Endocrine Diseases; Eye diseases; Heart Diseases; Male Reproductive Diseases; Nervous System Diseases See More

Summary Summary

Myotonic dystrophy type 1 (MD1), one of the two types of myotonic dystrophy, is an inherited type of muscular dystrophy that affects the muscles and other body systems (e.g., heart, eyes, endocrine system, and central nervous system).^[1] MD1 has three forms that somewhat overlap: the mild form, classic form, and congenital form (present at birth). The mild form has the least severe symptoms of the different forms of MD1 and is associated with a normal life span. The classic form is characterized by muscle weakness and wasting, prolonged muscle tensing (myotonia), cataract, and often, abnormal heart function. Adults with the classic form may become physically disabled and may have a shortened life span. The congenital form is characterized by severe generalized weakness at birth (hypotonia), often causing complications with breathing and early death. MD1 is inherited in an autosomal dominant manner and is caused by mutations in the DMPK gene. Treatment is based on the signs and symptoms present.^[2]

Last updated: 5/19/2017

Symptoms Symptoms

People with MD1 have progressive muscle wasting and weakness beginning in their 20's or 30's. The muscle wasting and weakness develop in their lower legs, hands, neck and face. They also have stiffness and tightness of their muscles (called myotonia), so they are slow to relax certain muscles after using them. This condition is characterized by difficulty releasing the hand from a handshake or a doorknob. In addition to muscle weakness and wasting, people who have MD1 may have fatigue, muscle pain, difficulty swallowing, clouding of the lens in their eyes (cataracts), and irregularities in the electrical control of their heartbeat (cardiac conduction defects). People with advanced disease may develop respiratory complications. Men with MD1 have changes in their hormones that can cause balding and sometimes the inability to father a child (infertility).^[1]^[2] The severity of symptoms varies among people with MD1.

Compared to myotonic dystrophy type 2, MD1 is more severe and may affect lifespan.^[2]

Last updated: 5/19/2017

The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.

Signs and Symptoms	Approximate number of patients (when available)
EMG abnormality	Very frequent (present in 80%-99% of cases)
First degree atrioventricular block	Very frequent (present in 80%-99% of cases)
Hypertonia	Very frequent (present in 80%-99% of cases)
Intellectual disability, severe	Very frequent (present in 80%-99% of cases)
Mask-like facies	Very frequent (present in 80%-99% of cases)
Myotonia	Very frequent (present in 80%-99% of cases)
Skeletal muscle atrophy	Very frequent (present in 80%-99% of cases)
Abnormal hair quantity	Frequent (present in 30%-79% of cases)
Abnormality of cardiovascular system morphology	Frequent (present in 30%-79% of cases)
Abnormality of the endocrine system	Frequent (present in 30%-79% of cases)
Cataract	Frequent (present in 30%-79% of cases)
Facial palsy	Frequent (present in 30%-79% of cases)
Intellectual disability, progressive	Frequent (present in 30%-79% of cases)
Muscular hypotonia	Frequent (present in 30%-79% of cases)
Respiratory distress	Frequent (present in 30%-79% of cases)
Testicular atrophy	Frequent (present in 30%-79% of cases)
Abnormality of the upper urinary tract	Occasional (present in 5%-29% of cases)
Cryptorchidism	Occasional (present in 5%-29% of cases)
Hernia of the abdominal wall	Occasional (present in 5%-29% of cases)
Hip dislocation	Occasional (present in 5%-29% of cases)
Hydrocephalus	Occasional (present in 5%-29% of cases)
Non-midline cleft lip	Occasional (present in 5%-29% of cases)
Strabismus	Occasional (present in 5%-29% of cases)
Atrial fibrillation	Very rare (present in 1%-4% of cases)
Atrial flutter	Very rare (present in 1%-4% of cases)
Autosomal dominant inheritance	-
Cerebral atrophy	-
Cholelithiasis	-
Decreased fetal movement	-
Dysphagia	-
Excessive daytime sleepiness	-
Facial diplegia	-
Feeding difficulties in infancy	-
Frontal balding	-
Hypogonadism	-
Obsessive-compulsive trait	-
Polyhydramnios	-

Last updated: 9/1/2017

Cause Cause

MD1 is caused by a mutation called a CTG trinucleotide repeat in the DMPK gene.^[1]^[2] It is made up of three DNA building blocks (CTG stands for cytosine, thymine, and guanine) that appear multiple times in a row. If the number of CTG repeats is more than 34, it creates an unstable region in the gene.^[1]^[2] Repeats between 35 and 49 are considered premutations. Individuals with CTG repeats in this range do not have symptoms themselves, but their children are at increased risk of inheriting a larger repeat size and thus having symptoms.^[2]

The protein made by the DMPK gene is believed to play a role in communication and impulse transmission within and between cells. It appears to be important for the correct functioning of cells in the heart, brain, and skeletal muscles.^[1]^[2] The more than normal number of CTG repeats leads to the creation of longer and toxic RNA. This causes problems for cells mainly because it traps and disables important proteins.^[3] This prevents cells in muscles and other tissues from functioning normally, leading to the signs and symptoms of MD1.^[1]^[2]^[3]

Last updated: 5/19/2017

Inheritance Inheritance

MD1 is inherited in an autosomal dominant pattern, which means one copy of the mutated gene in each cell is sufficient to cause the disorder. In most cases, the person with MD1 has a parent who also has the disorder.^[1]^[2] The children of a person with MD1 have a 50% chance of inheriting the disorder.^[2]

As myotonic dystrophy is passed from one generation to the next, the disorder generally begins earlier in life and signs and symptoms become more severe. This phenomenon is called anticipation. It is caused by an increase in the length of the number of CTG repeats (unstable region) in the DMPK gene.^[1] The expansion of the unstable region causes the features of the disorder to become more severe with each successive generation.

Some people diagnosed with MD1 have a parent who has the signs and symptoms of the disorder; others do not. A parent may appear to be unaffected because symptoms may be mild or absent. Genetic testing is available to confirm the presence of the condition. ^[2]

Last updated: 5/19/2017

Treatment Treatment

The resources below provide information about treatment options for this condition. If you have questions about which treatment is right for you, talk to your healthcare professional.

Management Guidelines

GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
Orphanet Emergency Guidelines is an article which is expert-authored and peer-reviewed that is intended to guide health care professionals in emergency situations involving this condition.

Do you have updated information on this condition? Let us know.

Research Research

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

ClinicalTrials.gov lists trials that are studying or have studied Myotonic dystrophy type 1. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Patient Registry

In 2000, the National Registry for Myotonic Dystrophy (DM) and Facioscapilohumeral Muscular Dystrophy (FSHD) was developed at the University of Rochester in Rochester, New York with funding from the National Institutes of Health (NIH). It was developed to facilitate research by making available to investigators anonymous data on Registry members, by helping investigators recruit subjects into their clinical studies, and by providing educational materials to patients and family members.

Organizations Organizations

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Muscular Dystrophy Association (MDA)
222 S Riverside Plaza
Suite 1500
Chicago, IL 60606
Toll-free: 800-572-1717
TTY: 1-800-572-1717
E-mail: mda@mdausa.org
Website: http://www.mdausa.org/
Muscular Dystrophy UK
61A Great Suffolk Street
London, SE1 0BU United Kingdom
Toll-free: 0800 652 6352 (Helpline)
Telephone: (+44) 0 020 7803 4800
E-mail: info@musculardystrophyuk.org
Website: http://www.musculardystrophyuk.org/
Myotonic Dystrophy Foundation
1004-A O'Reilly Avenue
San Francisco, CA 94129
Toll-free: 86-MYOTONIC or 866-968-6642
Telephone: 415-800-7777
E-mail: info@myotonic.org
Website: http://www.myotonic.org

Do you know of an organization? Send us your suggestions.

Living With Living With

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Genetics Resources

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by GeneTests, the American College of Medical Genetics, and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.

Learn More Learn More

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

Genetics Home Reference (GHR) contains information on Myotonic dystrophy type 1. This website is maintained by the National Library of Medicine.
The Muscular Dystrophy Association (MDA) provides additional information about myotonic dystrophy. Click on the link to view this information.
Myotonic Dystrophy Foundation provides additional information about Myotonic dystrophy type 1.
The National Human Genome Research Institute's (NHGRI) website has an information page on this topic. NHGRI is part of the National Institutes of Health and supports research on the structure and function of the human genome and its role in health and disease.

In-Depth Information

The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine.
Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
PubMed is a searchable database of medical literature and lists journal articles that discuss Myotonic dystrophy type 1. Click on the link to view a sample search on this topic.

Selected Full-Text Journal Articles

Mulders SAM et al., Molecular therapy in myotonic dystrophy: Focus on RNA gain-of-function. Human Molecular Genetics. 2010:19(1):R90-R97.

News & Events News & Events

News

Don’t Miss the NCATS Toolkit for Patient-Focused Therapy Development Event
August 31, 2017
Funding Opportunities Now Available for the Undiagnosed Diseases Network (UDN) Phase II
August 30, 2017
IRDiRC Goals 2017-2027: New Rare Disease Research Goals for the Next Decade
August 10, 2017

NCATS Co-Sponsored Conferences

Gordon Research Conferences CAG Triplet Repeat Disorders and the associated Graduate Research Seminar Saturday, June 22, 2013 - Friday, June 28, 2013
Location: Waterville Valley Resort, Waterville Valley, NH
Description: The 2013 Gordon Research Conference on CAG Triplet Repeat Disorders will bring together top scientists from around the world to discuss high-impact, interdisciplinary research on CAG Triplet Repeat Disorders. The objective of the conference is to promote scientific discussion and facilitate interdisciplinary exchange by bringing leading researchers in the field together with a broad range of experts representing; clinicians, diagnosticians, neurobiologists, pathologists, geneticists and molecular biologists.

Contact: Miles Fabian(301) 594-3827fabianm@mail.nih.gov

Co-funding Institute(s): National Institute of Neurological Disorders and Stroke, Office of Rare Diseases Research
8th International Myotonic Dystrophy Consortium Meeting Wednesday, November 30, 2011 - Saturday, December 3, 2011
Location: Sheraton Sand Key, Clearwater , FL
Description: The 8th International Myotonic Dystrophy Consortium Meeting (IDMC-8) will be held at the Sheraton Sand Key Resort in Clearwater Beach Florida November 30 – December 3 2011. This year, the meeting will be preceded by the Outcome Measures for Myotonic Dystrophy on Wednesday November 30 (place website link here) and followed by the EMPOWER2011 Myotonic Dystrophy Family Conference . Participation to the Outcome Measures for Myotonic Dystrophy meeting is by invitation-only while EMPOWER2011 is open to all families living with myotonic dystrophy.

Contact: Dr. John D. Porter(301) 496-1917porterjo@ninds.nih.gov

Co-funding Institute(s): National Institute of Neurological Disorders and Stroke, Office of Rare Diseases Research
- Agenda ( - 94KB)
2009 Triplet Repeat Disorders Gordon Conference Sunday, May 31, 2009 - Friday, June 5, 2009
Location: Waterville Valley, NH
Description: The top two priorities of this conference were training and the communication of cutting-edge science in the area of CAG triplet repeat disorders. The focus of this conference was on areas of rapid advancement and latest developments. Speakers were selected for their expertise, recent contributions to the field, and ability to provide lively presentations. The structured discussion leaders were instructed to focus on issues that cut across each presentation in a session.

Contact: Dr. Margaret Sutherland, NINDS 301-496-5680

Co-funding Institute(s): National Institute of Neurological Disorders and Stroke
- Agenda ( - 88KB)

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Myotonic dystrophy

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Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

My son is a young adult and has myotonic dystrophy type 1. He has early cataracts and many other symptoms. He wears glasses and appears recently to have a wandering eye. He also has double vision and fatigue. Is this caused by the myotonic dystrophy? What treatment is recommended? See answer
My girlfriend's grandmother has Myotonic dystrophy type 1. Fortunately neither my girlfriend's mother nor father is affected, but this disease is quite common in her mother's family. I want to know the probability that either my girlfriend or our children could get this disease. See answer

Have a question? Contact a GARD Information Specialist.