National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Myotonic dystrophy type 1

Información en español


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:
This disease is grouped under:
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
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.

Showing of 112 |
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
More than typical sleepiness during day
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
Excessive daytime sleepiness 0002189
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 112 |
Last updated: 7/1/2020
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
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

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.  

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

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

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

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

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

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


  1. Myotonic Dystrophy. Genetics Home Reference. November 2010; http://ghr.nlm.nih.gov/condition/myotonic-dystrophy.
  2. Bird TD. Myotonic Dystrophy Type 1. GeneReviews. October 22, 2015; https://www.ncbi.nlm.nih.gov/books/NBK1165/.
  3. Wahl M. MMD Research: Seeking yo Free Proteins from a 'Toxic Web'. Muscular Dystrophy Assocation (MDA). June 20, 2012; https://www.mda.org/quest/article/mmd-research-seeking-to-free-proteins-from-a-toxic-web.