Myotonic Muscular Dystrophy Type 1

Guidance for primary care clinicians diagnosing and managing children with myotonic muscular dystrophy

Myotonic muscular dystrophy is a multisystem disorder that affects the brain, skeletal and smooth muscles, eyes, heart, gastrointestinal tract, lungs, and endocrine system. The 2 forms, type 1 and type 2, are caused by different gene mutations. Type 2 has no congenital or early childhood form and is not discussed further here. Type 1 can be classified into mild (late onset), classic (adult onset), childhood/juvenile, and congenital forms. The classification describes a continuum ranging from mild to severe disease, which generally correlates with trinucleotide repeat (CTG) length. Myotonic muscular dystrophy type 1 is a progressive condition; repeat expansion and RNA splicing dysregulation increases over time and leads to a gradual worsening in many domains, including cognition, muscle strength, and others.

Other Names

Congenital myotonic muscular dystrophy
Dystrophia myotonica
Myotonic dystrophy
Steinert disease

Key Points

Myotonic muscular dystrophy type 1 may present as global developmental delay
Early myotonic muscular dystrophy may present as a global developmental delay in a child with an uneventful birth. The characteristic myotonia is not present until later in childhood, and the typical facial features may not be obvious unless the provider is aware of the potential for this underlying diagnosis in a child with developmental delays.

Assess cardiac symptoms immediately
Any symptoms suggestive of cardiac arrhythmia (e.g., chest pain with exertion, light-headedness, or palpitations) should be taken seriously.

Manage fatigue
Fatigue is an ongoing problem. Clinically, this is observed in older children who still need naps to function well. Consider a sleep study for obstructive or central sleep apnea when fatigue or daytime sleepiness are present. School accommodations may be necessary for children with fatigue. [Johnson: 2015] Consider suggesting a disability placard for the family's car to help conserve the child's energy while out of the house; even if the child is only going to run around at a park, the child should conserve energy to get to the play area.

Complications with anesthesia
Individuals with myotonic muscular dystrophy type 1, even those with mild manifestations, have a higher rate of complications associated with general anesthesia. Families should be educated about this possibility and reminded of this during well-child visits. [Mangla: 2019] See the anesthesia guidelines available at Anesthesia & Myotonic Dystrophy - Risks & Recommendations (MDF).

Medication considerations
Begin any sedating medications at half the typical dose. These patients are sensitive to sedating medications and are at risk for associated respiratory depression. Any medication that prolongs the QT should be evaluated in the context of that patient's current ECG. Often, pain is myotonia. Rather than traditional pain medications, consider trying anti-myotonia medications. Statins may lead to increasing muscle weakness and pain.

Incidence of diabetes
Individuals with myotonic muscular dystrophy type 1 may have insulin resistance that sometimes develops into diabetes, even in the absence of obesity.

Bacterial infections
There is an increased risk of pneumonia in the setting of upper respiratory infections due to weakness of the muscles required for optimal respiration.


Standard of care guidelines were first published in 2010 and updated in 2018 to include new recommendations on the transition from pediatric to adult care, endocrine management, primary care, and emergency management. No practice guidelines have been published. Guidance based on expert opinion includes:

Lagrue E, Dogan C, De Antonio M, Audic F, Bach N, Barnerias C, Bellance R, Cances C, Chabrol B, Cuisset JM, Desguerre I, Durigneux J, Espil C, Fradin M, Héron D, Isapof A, Jacquin-Piques A, Journel H, Laroche-Raynaud C, Laugel V, Magot A, Manel V, Mayer M, Péréon Y, Perrier-Boeswillald J, Peudenier S, Quijano-Roy S, Ragot-Mandry S, Richelme C, Rivier F, Sabouraud P, Sarret C, Testard H, Vanhulle C, Walther-Louvier U, Gherardi R, Hamroun D, Bassez G.
A large multicenter study of pediatric myotonic dystrophy type 1 for evidence-based management.
Neurology. 2019;92(8):e852-e865. PubMed abstract

Johnson NE, Aldana EZ, Angeard N, Ashizawa T, Berggren KN, Marini-Bettolo C, Duong T, Ekström AB, Sansone V, Tian C, Hellerstein L, Campbell C.
Consensus-based care recommendations for congenital and childhood-onset myotonic dystrophy type 1.
Neurol Clin Pract. 2019;9(5):443-454. PubMed abstract / Full Text


It is easy to miss the diagnosis of MMD in babies unless the diagnosis is kept in mind when considering a child with respiratory and/or feeding problems, hypotonia, and/or global developmental delays without a family history of the disease. When the newborn or infant presents with these problems, assess the face of the mother (and father) for weakness, ptosis, and hollow temples. To further assess the parents, perform percussion myotonia testing on the tongue and thenar eminences. Have the parent close eyes and fists and hold them tightly for several minutes, then let go suddenly. Individuals with myotonia demonstrate a slow release. An electromyogram in the parent may also demonstrate myotonia associated with MMD if it is not clinically apparent.
Parents may describe pregnancy complicated by polyhydramnios and/or decreased fetal movements; prolonged or complicated labor; the presence of developmental hip dysplasia and/or clubfeet; breathing and feeding problems near birth, including the inability to breast/bottle feed; difficulties learning to eat as an infant; failure to thrive.
Individuals with mild late adult onset may not develop symptoms until after 50 years old. [Ho: 2015] Classic "adult" onset often occurs after age 10 and involves progressive muscle weakness (often eventually requiring a wheelchair for mobility), cataracts, and cardiac conduction abnormalities. Children with childhood onset (before age 10 but after early infancy) often have similar symptoms and disease progression as those with congenital onset. Infants with congenital onset may present at birth with hypotonia, breathing or feeding problems, and drooling and/or swallowing problems. Global developmental delays are often observed in the first few years of life. Distal muscle atrophy and weakness, as well as the hallmark myotonia, may not be noted until school age or later. IQ may be borderline or low, learning disabilities may be present, and attention deficit hyperactivity disorder or characteristics of autism spectrum disorder are common. Management is currently supportive, incorporating regular surveillance and treatment of manifestations.


Mild and classic presentations: Cataracts, cardiac arrhythmias, speech and swallowing problems, fatigue, sleep disorders (including central and obstructive sleep apnea), and early onset of type II diabetes may occur. Less severely affected children may be identified when they fail to meet early developmental milestones.
Congenital/severe presentations: Babies with congenital myotonic muscular dystrophy may be identified at birth with severe hypotonia, positional problems such as clubfeet or hip dysplasia, and breathing or swallowing problems. The last 2 issues may be severe enough to require ventilation or tube feeding, sometimes for prolonged periods. Global developmental delays are often observed in the first few years of life. Distal muscle atrophy and weakness, as well as the hallmark myotonia, may not be noted until school age or later. IQ may be borderline or low, learning disabilities may be present, and attention deficit hyperactivity disorder or characteristics of autism spectrum disorder are common.

Diagnostic Criteria & Classifications

Diagnosis is made by molecular testing confirming presence of the CTG repeat expansion in the DMPK gene of chromosome 19.
For myotonic muscular dystrophy:
  • Myotonic muscular dystrophy type 1, the most common type, results from an abnormal DNA expansion (CTG) in the DMPK gene on chromosome 19, causing mis-splicing of mRNAs, affecting all organs.
  • Myotonic muscular dystrophy type 2 arises from an abnormal expansion of DNA (CCTG) in the first intron of CNBP (cellular nucleic acid binding protein). Unlike myotonic muscular dystrophy type 1, where the number of repeats is roughly correlated with the severity of the disease, there is no correlation between phenotype and repeat length.
Types of Myotonic Dystrophy (MDA) and [Wenninger: 2018] provide further details.

Screening & Diagnostic Testing

Genetic Testing

Diagnosis is by genetic testing for the CTG repeat expansion in the DMPK gene on chromosome 19. Molecular genetic testing is available for diagnosis and is relatively inexpensive; it often obviates biopsy and electromyography.

Genetics & Inheritance

Myotonic muscular dystrophy type 1 results from a trinucleotide repeat (CTG) in the DMPK gene region on chromosome 19. It is one of the many examples of neurologic diseases, such as Huntington disease and fragile X syndrome, caused by an excessive number of such repeats (a CTG repeat length of 35 or more is abnormal). Children with congenital myotonic muscular dystrophy often have >1000 repeats, though the congenital form may be seen with fewer repeats. In the case of myotonic muscular dystrophy type 1, these repeats are present in the RNA, but they are not translated into the protein. The disease mechanism for these untranslated repeats is called the “toxic RNA hypothesis.” In this disease model, the excessive CTG repeats bind RNA-binding proteins important in splicing (editing) other RNAs besides DMPK. This leads to RNA splicing errors, which have been detected in many different proteins in the brain (amyloid precursor protein), heart (troponin), muscle (chloride ion channel), and endocrine systems (insulin receptor). This could explain why myotonic muscular dystrophy type 1 is a multisystemic disorder. [Wheeler: 2007]
Myotonic muscular dystrophy type 1 is inherited in an autosomal dominant fashion. The disease-causing allele found in a parent may lengthen during the process of gametogenesis, and the resulting offspring may have more severe disease and earlier onset than seen in the parent. This phenomenon is called anticipation. Anticipation resulting in large expansions (>1000 repeats), and hence congenital myotonic muscular dystrophy, is much more common when the mother is the affected parent; anticipation with smaller or moderate expansions can occur from either parent. [Pratte: 2015]
Since myotonic muscular dystrophy type 1 can worsen in successive generations, the diagnosis of an infant with the congenital form may lead to the recognition of milder symptoms in parents and other relatives. These symptoms or historical features may include a family history of early heart disease or pacemaker use, problems with fatigue, cataracts before age 50, learning problems, and distal muscle weakness. It is important to screen at-risk relatives (e.g., siblings and parents) since early diagnosis allows treatment of complications, such as cardiac abnormalities or diabetes.


MMD is the most common muscular dystrophy. [Norwood: 2009] It affects an average of 1:2000 people in the United States. [Johnson: 2019] In most populations, type 1 appears to be more common than type 2, but prevalence varies in different ethnic populations and the founder effect may increase the prevalence in specific regions. [Theadom: 2014] [Pratte: 2015]

Differential Diagnosis

Differential diagnoses include many less common muscle and nerve diseases, such as distal muscular dystrophies and Dejerine Sottas disease (a type of hereditary motor sensory neuropathy with evidence seen on EMG/NCV testing), and hyperkalemic periodic paralysis (which presents with episodic weakness).
Because of the intellectual disability associated with myotonic muscular dystrophy, diseases of the central nervous system may also be considered. Metabolic testing is normal in myotonic dystrophy. Although brain MRI is usually normal in individuals with myotonic muscular dystrophy type 1, it may show periventricular myelin changes that could be interpreted as evidence of perinatal hypoxic/ischemic injury. [Modoni: 2004] [Peglar: 2019]

Comorbid Conditions

Increased rates of autism spectrum disorder, intellectual disability, and attention-deficit hyperactivity disorder have been reported in this population. [Ekström: 2008] Diagnosis and management information can be found at:


Age of onset and severity of symptoms are variable. Mild presentation can involve cataracts and mild myotonia. Severe presentation can involve breathing issues, swallowing problems, or life-threatening cardiac arrhythmias. While no cure or treatment slows myotonic muscular dystrophy's progression, early intervention can reduce or eliminate some complications.

Treatment & Management

Although children with myotonic dystrophy often seem to be doing fairly well, a survey performed in the US and Canada revealed that children with myotonic dystrophy are concerned about communication and hand/finger problems. Parents were also concerned about their child’s communication but also noted that fatigue was a major problem in daily functioning. [Johnson: 2015] [Hagerman: 2019]

Knockdown of the toxic repeat expansion may be possible using antisense oligonucleotides. A clinical trial (NCT02312011) tested this approach. We expect others to continue to improve on this approach in the near future. Gene therapy for myotonic dystrophy is likely still years away, but adeno-associated viral vector gene therapy is being worked on. [Crudele: 2019]

Since myotonic muscular dystrophy type 1 is a multi-system disease:

  • Perform a complete, age-appropriate evaluation in all children. Initiate developmental therapies based on delays. Intellectual disability and other psychological symptoms are seen in more than half of children with congenital myotonic muscular dystrophy. A neuropsychological profile may be helpful.
  • Children with MMD require an ECG yearly to screen for progressive arrhythmias, atrial fibrillation, and conduction defects (less commonly cardiac muscle problems). Any detection of an early arrhythmia, most commonly first-degree heart block, requires an urgent evaluation by a cardiologist.
  • Consider a barium swallow study for symptoms of dysphagia, drooling, or frequent pulmonary infections that may be due to silent aspiration.
  • Ophthalmologic evaluation should be performed at diagnosis. Although cataracts (posterior subcapsular/cortical type) are unusual in young children, strabismus and ptosis are common.
  • Children may have thyroid function and diabetes; consider annual screening with a TSH and HbA1c.
  • Screen for sensorineural hearing loss, which is present in more than half of individuals with myotonic muscular dystrophy type 1.
  • Children should have a sleep study at diagnosis or when new symptoms of daytime sleepiness occur to screen for sleep apnea. Sleep and fatigue are often reported as the most debilitating symptoms of myotonic muscular dystrophy type 1.

Children should be managed within a medical home, with input from the family, unless a multidisciplinary Neuromuscular Clinic (see Neuromuscular Clinics (see NM providers [1])) is available. The goal is to avoid duplication of services or unnecessary appointments while still seeing the subspecialists needed. All screening and interventions are intended to promote growth and potential development, mitigate cumulative morbidities, optimize function, and limit mortality while maximizing quality of life. [Kang: 2015]


Neurological signs and symptoms may include hand, tongue, and eyelid myotonia. Hand muscles will often be weak and atrophied. Weakness begins in the distal finger flexors and ankle dorsiflexors. Often children will have ptosis and severe oral facial weakness and may exhibit drooling, problems swallowing, especially liquids, and frequent coughing. Treatment for these problems is symptomatic. Although they are rarely used in children, medications for myotonia may be helpful (phenytoin, mexiletine, others).


Global developmental delay is almost universal in children with congenital myotonic muscular dystrophy. Begin early intervention when the child is 0 -3 years old. Transition to special education preschool and school as needed. Physical, occupational, feeding, and/or speech therapy may also be necessary.


Children with congenital myotonic muscular dystrophy may be born with club feet and hip dysplasia. They will need monitoring for progression of muscle weakness leading to contractures of heels, knees, and hips either in the neuro-muscular clinic or separately with orthopedics. About 30% of adolescents with myotonic muscular dystrophy type 1 demonstrate kyphosis/scoliosis, and surgery may be necessary in some cases. [Canavese: 2009] If muscle weakness is present, a disability placard for the family car can help to minimize the child's fatigue.
Botox may cause worsening in targeted muscle groups.
Avoid using neuromuscular blocking agents (e.g., botulinum toxin) in patients with myotonic muscular dystrophy unless the contractures are determined to cause significantly greater impairment than would any potential worsening of weakness in the targeted muscle groups. [Kang: 2015]


Depending on the severity of the disease, mobility may be significantly affected because of global developmental delays and/or muscle weakness. Positional aids may be necessary if the child cannot sit without assistance. A corner chair, tumble form, or wheelchair may be used to allow the child to be in a seated position for feeding and optimal hand use during play and activities of daily living. Braces and splints may be used to prevent deformity and to provide support or protection. These may be prescribed for use during the day or night to provide stretching and optimal joint positioning. Standers and/or walkers can allow for standing and help with balance when walking. Weight-bearing activities help prevent osteoporosis, allow full lung expansion, stretch hamstrings, and allow children to be on-level with peers.


Fatigue in infants and children may manifest as a need to take frequent naps past the usual age of napping. In addition to skeletal muscle weakness, respiratory muscles may be weak, adding to fatigue with activity.
Sleep apnea (either central or obstructive), excessive leg movements, and dysregulation of rapid eye movement sleep may also contribute to fatigue in some children. If sleepiness, restless legs, or breathing abnormalities during sleep continue, consider referring to a sleep specialist. In more severe cases, stimulant medication or modafinil (Provigil) may be helpful. In younger children, a behavioral approach may help; the family should control bedtime and wake-up time and plan for scheduled naps.


Individuals with myotonic muscular dystrophy type 1 may have conduction problems and arrhythmias that can be life-threatening. In one study, the risk of cardiac conduction disorder was 60 times the population risk.[Johnson: 2015] Although it is difficult to predict the age that these complications first occur, children as young as age 10 have demonstrated arrhythmias, particularly during exercise. Visits with a cardiologist and annual EKGs are recommended to detect asymptomatic arrhythmias. [Bassez: 2004] [Groh: 2012]

Gastro-Intestinal & Bowel Function

Gastroesophageal reflux is very common, although it might present as arching, irritability, or food refusal rather than vomiting. Treatment can be started empirically with evaluation and/or a referral to gastroenterology if symptoms continue. Treatment is generally initiated with lansoprazole, a proton pump inhibitor. Treatment of reflux can be augmented by the use of a motility agent (metoclopromide or low-dose erythromycin) or H2 blocker, but the clinician must monitor closely for side effects, particularly irritability or dystonia with metoclopromide. If optimal reflux treatment is not successful, and/or the child remains underweight or has frequent aspiration pneumonias, a Nissen or other type of fundoplication may be necessary. Gastroesophageal Reflux Disease provides management details.
Most children with myotonic muscular dystrophy experience constipation alternating with diarrhea. Constipation and diarrhea are easier to treat if caught early; bowel history should be part of every medical home visit. Dietary management with additions of fiber might be all that is necessary, but many children will need daily treatment with laxatives (PEG 3350, MiraLax, or GlycoLax). See ConstipationConstipation for treatment details.
Children may have prolonged urinary and fecal incontinence. A high-fiber diet may help reduce fecal urgency. If incontinence persists into the teenage years, a trial of anti-myotonia medication may be helpful.


Respiratory muscle weakness can be life-threatening in infants with congenital myotonic muscular dystrophy. Although some infants may require mechanical ventilation for a prolonged period, they usually improve with time. Since children with myotonic muscular dystrophy, especially those with swallowing problems, are at an increased risk for pneumonias and other respiratory illnesses, administer influenza, H1N1, and pneumococcal vaccines as appropriate. Remind families to seek oseltamivir phosphate (Tamiflu) during flu season at the onset of flu-like symptoms. As noted above, children are at significantly increased risk of obstructive and central sleep apnea and may benefit from periodic sleep studies. Once children with congenital onset recover from the respiratory failure seen in infancy, they are at minimal risk of experiencing respiratory decline during childhood and do not necessarily need regular pulmonary function tests.


In children with early-onset myotonic muscular dystrophy, parents and the affected children reported frequent and severe issues involving communication. [Johnson: 2015] Regular speech therapy may improve communication problems.

Nose, Throat, Mouth, Swallowing

Children with congenital myotonic muscular dystrophy have facial muscle weakness that can cause a seemingly flattened affect, an upper lip that comes to a point (known as a tented upper lip), and a characteristically long face with hollowing at the temples. A high-arched palate may be noted.
Swallowing dysfunction may result in drooling, salivary pooling, malnutrition, and/or pulmonary aspiration. A speech therapist (or, in some locations, an occupational therapist) can evaluate swallowing function and safety, determine if interventions (e.g., speech therapy, special feeding techniques, improved feeding position) might lead to improvements in function, and determine the safest and most efficient textures for eating. In some cases, the therapist may suggest a fluoroscopic video swallow study (also called a modified barium or cookie swallow). If dysphagia is a problem, diets using Thickened Liquids & Modified Foods may be necessary to prevent aspiration.
Children with significant swallowing problems may need gastrostomy tube placement to allow efficient and safe liquid and/or food delivery. A gastrostomy tube may also be necessary for those children with severe failure to thrive, even if aspiration is not an obvious problem. In some children, placement of a feeding tube might be thought of as a temporary intervention so that the family may focus on the child and the quality of their eating without constantly worrying about the number of calories the child has received. Treatment with a Nissen fundoplication may be important for children with gastroesophageal reflux disease and limited capacity to protect their airways. See Feeding Tubes & Gastrostomies in Children for more information.
Many parents choose not to treat drooling due to concerns about the side effects of medication and surgery. However, drooling in the socially aware older child can be very embarrassing and create social barriers. Treatment possibilities include medications to decrease saliva, botulinum toxin treatments (temporary), or surgery to block salivary ducts. No known therapy helps oropharyngeal function. [Morgan: 2012] See Drooling in Children with Special Health Care Needs for resources and information about specific treatments.

Nutrition, Growth, Bone

Children with congenital myotonic muscular dystrophy may have a combination of swallowing problems, constipation, and gastroesophageal reflux disease that leads to malnutrition. Children often have difficulty gaining and maintaining weight, but stature is typically normal. Careful monitoring of growth and weight gain in children with congenital myotonic muscular dystrophy is critical. Interventions may include optimizing oral feeding, adding oral caloric supplements, NG/NJ feeding, and placing a permanent feeding tube. The medical home should ensure that treatment of dysphagia, gastroesophageal reflux disease, delayed gastric emptying, and constipation is optimized. Intervention should be tailored to the child's needs and be family-centered. Boosting Calories for Babies, Toddlers, and Older Children and Formulas for information on increasing calories in the child's diet.


Males with myotonic muscular dystrophy type 1 may be hypogonadotropic and require testosterone supplementation to achieve secondary sexual characteristics. They may also be infertile, but this should not be assumed.
Females with myotonic muscular dystrophy type 1 should understand that their child has a 50/50 risk of being born with congenital myotonic muscular dystrophy in a more severe form than the mother exhibits. Pregnancies of mothers with congenital myotonic muscular dystrophy should be managed by a high-risk obstetrician, usually with birth planned for a tertiary care NICU. Labor may be prolonged, with an increased risk of retained placenta and hemorrhage. The woman may have polyhydramnios and note that fetal movements are decreased. See Sexuality & Children with Disabilities and Contraception & Menstrual Management.


Children with myotonic muscular dystrophy may have a number of endocrine concerns, including thyroid problems, diabetes, and delayed puberty. Typically, screening labs, including TSH and HbA1c, are required yearly. There are no specific treatment recommendations unique to myotonic muscular dystrophy.


Athletic activities enhance psychological health and help counter a drop in gross motor function, partly due to de-conditioning, as the child grows. Success depends upon the appropriate choice of activities, adapted equipment, adapted rules when appropriate, and support from peers, other parents, and coaches. The medical home can foster participation by including these activities in the management plan. The need for adapted physical education and/or supports or social structuring on the playground should also be included in the child's IEP (see School Accommodations: IEPs & 504s). Social integration should be promoted through leisure to reduce social isolation. The Portal's section on Assistive Technology may be helpful for parents.


Strabismus and ptosis, sometimes requiring surgery, are common in children with congenital myotonic muscular dystrophy. Refer children to an ophthalmologist at diagnosis and then as necessary for re-evaluation. Cataracts don't typically appear until adolescence but need to be monitored annually.


Children with myotonic muscular dystrophy have an increased risk of developing caries, plaque, and gingivitis. This may be due to mouth muscle and tongue weakness, decreased jaw opening, salivary pooling, reflux, and behavior problems interfering with oral hygiene. Early preventive care with frequent follow-ups as necessary is recommended. For many children with congenital myotonic muscular dystrophy, sedation or anesthesia may be necessary for cleaning and/or dental work.


Patients with neuromuscular diseases are at increased risk of periprocedural complications, including airway problems, suboptimal pain control, pulmonary complications, prolonged recovery times, and complications from bed rest and deconditioning. [Kang: 2015] Before any surgical interventions and general anesthesia, physicians should discuss the increased risk of complications with families, especially because these factors may affect consent to certain elective procedures. [Kang: 2015] If surgery is needed, the anesthesiologist should be made aware of possible anesthetic complications, and children should be monitored longer than usual in the immediate postoperative period to diagnose and treat respiratory, nutritional, mobility, and gastrointestinal complications. See Anesthesia & Myotonic Dystrophy - Risks & Recommendations (MDF) for a summary of important considerations when administering general anesthesia to children with muscular dystrophy.


"Transition" refers to moving from the pediatric health care and educational environment to the adult health care system and occupational environment. Moving children of all abilities toward transition begins with messages of expectation, responsibility, and value. Although children with myotonic muscular dystrophy in special education will be served by the school system until they turn 22, start planning for transition in early adolescence, and consider vocational training and living arrangements (will the individual live alone, in a group home, etc.).
If necessary, apply for guardianship when the child turns 18. The often lengthy process usually includes psychological and medical evaluations and the involvement of a lawyer. At age 18, children in some states may become eligible for Medicaid or qualify for resources with the Division of Services for People with Disabilities (DSPD) even if they were previously ineligible based on family income. Families may want to read Guardianship/Estate Planning for more information. Also, the Portal's Transition Issues contains resources, checklists, and information about finding adult health care and insurance, guardianship and estate planning, living arrangements, and much more.

Services & Referrals

Neuromuscular Clinics (see NM providers [1])
Referral to a muscular dystrophy clinic for evaluation and genetic testing is recommended. Neurology follow-up may be available at specialized clinics.

Pediatric Orthopedics (see NM providers [7])
Consider a baseline visit with follow-up as necessary. Children with joint contractures and/or scoliosis may be managed concurrently with pediatric orthopedics.

Pediatric Gastroenterology (see NM providers [2])
The medical home should order multidisciplinary evaluations with swallow therapists, gastroenterologists, and radiologists if there is evidence of failure to thrive or respiratory symptoms (or both). Consider a referral for constipation, reflux, and/or failure to gain adequate weight.

Pediatric Physical Medicine & Rehabilitation (see NM providers [3])
Consider a referral to evaluate development and recommend interventions aimed at increasing function.

Physical Therapy (see NM providers [12])
Refer when help is needed for muscle strengthening, dealing with fatigue, or for a stander, walker, or wheelchair fitting. A consultation can help with school and home adaptations (e.g., the child who wants a bike for a present, but the parents don't know what to purchase, or the child is interested in obtaining a sporting wheelchair). Also, refer for range-of-motion exercises, orthotic devices, heel cord lengthening procedures, or a combination of these interventions for children as needed.

Pediatric Cardiology (see NM providers [3])
Clinicians should refer children with myotonic dystrophy for a baseline cardiac evaluation. The intervals of further evaluations should depend on the results of the baseline evaluation. [Kang: 2015] Exercise testing should be considered.

Medical Genetics (see NM providers [2])
A consultation is recommended to help with diagnosis and to help families understand genetic test results so they can make family-planning decisions. [Kang: 2015] If the family has further questions about the genetics of myotonic muscular dystrophy type 1, consider re-evaluation. Genetic counseling for teens with congenital muscular dystrophy should be offered on a developmentally appropriate basis.

Pediatric Neurology (see NM providers [5])
If an MMD or other muscle disease clinic is not available, the child should be referred to pediatric neurology and/or genetics, depending on local expertise, for a baseline exam and periodic assessments as needed and to monitor weakness and developmental issues.

Pediatric Pulmonology (see NM providers [4])
When available, refer to pulmonary or aerodigestive care teams with experience managing the interface among oropharyngeal function, gastric reflux and dysmotility, nutrition, and respiratory systems and providing anticipatory guidance concerning trajectory, assessment modalities, complications, and potential interventions. [Kang: 2015]

ICD-10 Coding

G71.11, Myotonic muscular dystrophy


Information & Support

For Professionals

Myotonic Dystrophy Type 1 (GeneReviews)
Detailed information addressing clinical characteristics, diagnosis/testing, management, genetic counseling, and molecular pathogenesis; from the University of Washington and the National Library of Medicine.

Myotonic Dystrophy (OMIM)
Information about clinical features, diagnosis, management, and molecular and population genetics; Online Mendelian Inheritance in Man, authored and edited at the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine

Myotonic Muscular Dystrophy Type 1 (Orphanet)
Overview of MMD1 (aka Steinert myotonic dystrophy) and links to more information, services, and other resources; from Orphanet, a French-coordinated consortium involving over 40 countries to provide a portal for information about rare diseases and orphan drugs.

Myotonic Muscular Dystrophy Type 2 (Orphanet)
Overview of MMD2 (aka proximal myotonic myopathy) and links to more information, services, and other resources; from Orphanet, a French-coordinated consortium involving over 40 countries to provide a portal for information about rare diseases and orphan drugs.

For Parents and Patients

Facts about Myotonic Muscular Dystrophy (MDA)
Excellent overview of myotonic muscular dystrophy written for the family and patient; Muscular Dystrophy Association.

Myotonic Dystrophy Foundation
A non-profit that provides adaptive equipment and emotional support to individuals and families affected by any of the neuromuscular diseases.

Muscular Dystrophy Association
The Muscular Dystrophy Association (MDA) covers many conditions including CMT, Duchenne muscular dystrophy, and spinal muscular atrophy. More information about these conditions, how to register, and clinic locations can be found here.

Muscular Dystrophy (NINDS)
Information about muscular dystrophy, treatment, prognosis, research, and links to other organizations; National Institute of Neurological Disorders and Stroke.

Services for Patients & Families in New Mexico (NM)

For services not listed above, browse our Services categories or search our database.

* number of provider listings may vary by how states categorize services, whether providers are listed by organization or individual, how services are organized in the state, and other factors; Nationwide (NW) providers are generally limited to web-based services, provider locator services, and organizations that serve children from across the nation.


Clinical Trials in Myotonic type 1 (
Studies looking at better understanding, diagnosing, and treating this condition; from the National Library of Medicine.

Authors & Reviewers

Initial publication: December 2013; last update/revision: January 2023
Current Authors and Reviewers:
Author: Lynne M. Kerr, MD, PhD
Reviewer: Nicholas Johnson, MD, MS-CI
Authoring history
2023: update: Lynne M. Kerr, MD, PhDA; Russell Butterfield, MD, PhDR
2020: update: Mary A. Murray, MDCA; Vandana Raman, MDCA
2016: update: Meghan S Candee, MD, MScR; Nicholas Johnson, MD, MS-CIR
2013: first version: Nicholas Johnson, MD, MS-CIA; Lynne M. Kerr, MD, PhDA
AAuthor; CAContributing Author; SASenior Author; RReviewer

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