Myotonic dystrophy type 1

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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

This disease is grouped under:

Myotonic dystrophy

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
Cardiac conduction abnormality		0031546
Distal muscle weakness	Weakness of outermost muscles	0002460
EMG: myotonic discharges		0100284
Excessive daytime somnolence	Excessive daytime sleepiness More than typical sleepiness during day [ more ]	0001262
Myotonia with warm-up phenomenon		0003740
Posterior subcapsular cataract		0007787
30%-79% of people have these symptoms
Abnormal rapid eye movement sleep		0002494
Abnormality of masticatory muscle		0410011
Atrial fibrillation	Quivering upper heart chambers resulting in irregular heartbeat	0005110
Fatigable weakness of bulbar muscles		0030192
Fatigue	Tired Tiredness [ more ]	0012378
Foot dorsiflexor weakness	Foot drop	0009027
Hypersomnia	Excessive sleepiness	0100786
Myalgia	Muscle ache Muscle pain [ more ]	0003326
Obstructive sleep apnea		0002870
Poor fine motor coordination		0007010
Prolonged PR interval		0012248
Prolonged QRS complex		0006677
5%-29% of people have these symptoms
Abnormality of the cerebral white matter		0002500
Abnormality of the tongue muscle		0040173
Abnormality of thyroid physiology	Abnormal thyroid function	0002926
Alopecia	Hair loss	0001596
Anxiety	Excessive, persistent worry and fear	0000739
Astigmatism	Abnormal curving of the cornea or lens of the eye	0000483
Bilateral ptosis	Drooping of both upper eyelids	0001488
Cerebral cortical atrophy	Decrease in size of the outer layer of the brain due to loss of brain cells	0002120
Cholelithiasis	Gallstones	0001081
Constipation		0002019
Decreased fertility	Abnormal fertility	0000144
Decreased fetal movement	Less than 10 fetal movements in 12 hours	0001558
Decreased serum testosterone level	Decreased serum testosterone levels Low serum testosterone level Low serum testosterone levels [ more ]	0040171
Depressivity	Depression	0000716
Diabetes mellitus		0000819
Diaphragmatic weakness	Weak diaphragm	0009113
Diarrhea	Watery stool	0002014
Distal amyotrophy	Distal muscle wasting	0003693
Dysarthria	Difficulty articulating speech	0001260
Early balding		0002234
Elevated hepatic transaminase	High liver enzymes	0002910
Facial diplegia		0001349
Falls		0002527
Global developmental delay		0001263
Handgrip myotonia		0012899
Hypercholesterolemia	Elevated serum cholesterol Elevated total cholesterol Increased total cholesterol [ more ]	0003124
Hypergonadotropic hypogonadism		0000815
Hyperinsulinemia		0000842
Hypermetropia	Farsightedness Long-sightedness [ more ]	0000540
Impaired visuospatial constructive cognition		0010794
Impotence	Difficulty getting a full erection Difficulty getting an erection [ more ]	0000802
Insulin resistance	Body fails to respond to insulin	0000855
Intellectual disability, borderline	Mental retardation, borderline	0006889
Intellectual disability, mild	Mental retardation, borderline-mild Mild and nonprogressive mental retardation Mild mental retardation [ more ]	0001256
Intestinal pseudo-obstruction		0004389
Left ventricular systolic dysfunction		0025169
Limited extraocular movements		0007941
Male hypogonadism	Decreased function of male gonad	0000026
Mental deterioration	Cognitive decline Cognitive decline, progressive Intellectual deterioration Progressive cognitive decline [ more ]	0001268
Mild fetal ventriculomegaly		0010952
Mood changes	Moody	0001575
Myotonia of the jaw		0012901
Myotonia of the upper limb		0012903
Nasogastric tube feeding in infancy		0011470
Neck flexor weakness	Neck flexion weakness	0003722
Neonatal hypotonia	Low muscle tone, in neonatal onset	0001319
Ophthalmoplegia	Eye muscle paralysis	0000602
Oral-pharyngeal dysphagia		0200136
Paranoia		0011999
Polyhydramnios	High levels of amniotic fluid	0001561
Proximal muscle weakness	Weakness in muscles of upper arms and upper legs	0003701
Reduced visual acuity	Decreased clarity of vision	0007663
Respiratory failure		0002878
Respiratory failure requiring assisted ventilation		0004887
Respiratory insufficiency due to muscle weakness	Decreased lung function due to weak breathing muscles	0002747
Secondary hyperparathyroidism		0000867
Short attention span	Poor attention span Problem paying attention [ more ]	0000736
Supraventricular tachycardia		0004755
Talipes equinovarus	Club feet Club foot Clubfeet Clubfoot [ more ]	0001762
Tented upper lip vermilion		0010804
Testicular atrophy	Testicular degeneration	0000029
1%-4% of people have these symptoms
Aggressive behavior	Aggression Aggressive behaviour Aggressiveness [ more ]	0000718
Atrial flutter		0004749
Autism		0000717
Brain neoplasm		0030692
Choroidal melanoma		0012054
Colon cancer		0003003
Dilated cardiomyopathy	Stretched and thinned heart muscle	0001644
Endometrial carcinoma		0012114
Growth hormone deficiency		0000824
Inability to walk		0002540
Neoplasm of the skin	Skin tumors Tumor of the skin [ more ]	0008069
Non-medullary thyroid carcinoma		0040198
Obsessive-compulsive trait	Obsessive-compulsive traits	0008770
Ovarian carcinoma		0025318
Pelvic girdle muscle weakness		0003749
Peripheral axonal neuropathy		0003477
Shoulder girdle muscle weakness	Weak shoulder muscles	0003547
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance		0000006
Cataract	Clouding of the lens of the eye Cloudy lens [ more ]	0000518
Cerebral atrophy	Degeneration of cerebrum	0002059
Dysphagia	Poor swallowing Swallowing difficulties Swallowing difficulty [ more ]	0002015
Feeding difficulties in infancy		0008872
First degree atrioventricular block		0011705
Frontal balding		0002292
Generalized hypotonia	Decreased muscle tone Low muscle tone [ more ]	0001290
Hypogonadism	Decreased activity of gonads	0000135
Intellectual disability, progressive	Mental retardation, progressive Progressive mental retardation [ more ]	0006887
Intellectual disability, severe	Early and severe mental retardation Mental retardation, severe Severe mental retardation [ more ]	0010864
Muscle weakness	Muscular weakness	0001324
Muscular hypotonia	Low or weak muscle tone	0001252
Myotonia		0002486
Respiratory distress	Breathing difficulties Difficulty breathing [ more ]	0002098

Showing of 111 |

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

Last updated: 2/1/2021

Do you have updated information on this disease? We want to hear from you.

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.

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 MedlinePlus Genetics.

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

A registry supports research by collecting of information about patients that share something in common, such as being diagnosed with Myotonic dystrophy type 1. The type of data collected can vary from registry to registry and is based on the goals and purpose of that registry. Some registries collect contact information while others collect more detailed medical information. Learn more about registries.

Registries for Myotonic dystrophy type 1:
National Registry of Myotonic Dystrophy and Facioscapulohumeral Muscular Dystrophy
The Myotonic Dystrophy Family Registry

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

Myotonic Dystrophy Foundation
1004-A O'Reilly Avenue
San Francisco, CA 94129
Toll-free: 1-86-MYOTONIC (1-866-968-6642)
Telephone: +1-415-800-7777
E-mail: info@myotonic.org
Website: https://www.myotonic.org
Myotonic Dystrophy Support Group
19-21 Main Road
Gedling
Nottingham
NG4 3HQ
United Kingdom
Telephone: 0808 169 1960
E-mail: contact@mdsguk.org
Website: http://www.myotonicdystrophysupportgroup.org/

Organizations Providing General Support

Muscular Dystrophy Association (MDA)
222 S Riverside Plaza
Suite 1500
Chicago, IL 60606
Toll-free: 1-833-275-6321 (Helpline)
E-mail: resourcecenter@mdausa.org
Website: https://www.mda.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: https://www.musculardystrophyuk.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

MedlinePlus Genetics 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.

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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

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