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: 4/20/2018

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: 4/20/2018

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms	Other Names	Learn More: HPO ID
80%-99% of people have these symptoms
EMG abnormality		0003457
First degree atrioventricular block		0011705
Hypertonia		0001276
Intellectual disability, severe	Early and severe mental retardation Mental retardation, severe Severe mental retardation [ more ]	0010864
Mask-like facies	Expressionless face Lack of facial expression Mask-like facial appearance [ more ]	0000298
Myotonia		0002486
Skeletal muscle atrophy	Muscle degeneration Muscle wasting [ more ]	0003202
30%-79% of people have these symptoms
Abnormal hair quantity		0011362
Abnormality of cardiovascular system morphology		0030680
Abnormality of the endocrine system		0000818
Cataract	Cloudy lens	0000518
Facial palsy	Bell's palsy	0010628
Intellectual disability, progressive	Mental retardation, progressive Progressive mental retardation [ more ]	0006887
Muscular hypotonia	Low or weak muscle tone	0001252
Respiratory distress	Breathing difficulties Difficulty breathing [ more ]	0002098
Testicular atrophy	Testicular degeneration	0000029
5%-29% of people have these symptoms
Abnormality of the upper urinary tract		0010935
Cryptorchidism	Undescended testes Undescended testis [ more ]	0000028
Hernia of the abdominal wall		0004299
Hip dislocation	Dislocated hips Dislocation of hip [ more ]	0002827
Hydrocephalus		0000238
Non-midline cleft lip		0100335
Strabismus	Cross-eyed Squint Squint eyes [ more ]	0000486
1%-4% of people have these symptoms
Atrial fibrillation		0005110
Atrial flutter		0004749
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance		0000006
Cerebral atrophy	Degeneration of cerebrum	0002059
Cholelithiasis	Gallstones	0001081
Decreased fetal movement		0001558
Dysphagia	Poor swallowing Swallowing difficulties Swallowing difficulty [ more ]	0002015
Excessive daytime sleepiness		0002189
Facial diplegia		0001349
Feeding difficulties in infancy		0008872
Frontal balding		0002292
Generalized hypotonia	Decreased muscle tone Low muscle tone [ more ]	0001290
Hypogonadism	Decreased activity of gonads	0000135
Muscle weakness	Muscular weakness	0001324
Obsessive-compulsive trait	Obsessive-compulsive traits	0008770
Polyhydramnios		0001561

Showing of 39 |

Do you have more information about symptoms of this disease? We want to hear from you.

Last updated: 6/1/2018

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: 4/20/2018

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: 4/20/2018

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

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.

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Find a Specialist Find a Specialist

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare 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 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.

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 related to 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? We want to hear from you.

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

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.
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.

Related Diseases Related Diseases

The following diseases are related to Myotonic dystrophy type 1. If you have a question about any of these diseases, you can contact GARD.

Myotonic dystrophy

GARD Answers GARD Answers

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

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