About Myotonic Dystrophy
Myotonic Dystrophy is caused by a trinucleotide repeat expansion in the DMPK gene (DM1) or CNBP gene (DM2). In DM1, a CTG repeat expands in the 3' untranslated region, while DM2 involves CCTG repeats. The pathophysiology involves toxic accumulation of mutant mRNA, which sequesters RNA-binding proteins and disrupts normal RNA splicing and protein production. This leads to dysfunction of multiple proteins, including myosin, chloride channels, and sarcoplasmic reticulum calcium release channels, resulting in muscle damage and myotonia. The trinucleotide repeat number correlates with disease severity and age of onset, with longer repeats generally causing more severe disease with earlier presentation.
DM1 shows two main phenotypes: classic form with adult onset and congenital form with severe neonatal presentation and intellectual disability. DM2 generally has milder symptoms than DM1. Beyond skeletal muscle, MD affects smooth muscle, cardiac muscle, and the brain. Cardiac involvement ranges from conduction abnormalities to arrhythmias and dilated cardiomyopathy. Cerebral manifestations include intellectual disability in congenital forms, behavioral changes, cognitive decline, and increased risk of central sleep apnea. Cataracts are common, developing in teenagers with DM1. Endocrine dysfunction includes testicular atrophy, insulin resistance, and thyroid abnormalities.
Common Symptoms of Myotonic Dystrophy
Recognizing the signs of Myotonic Dystrophy early can lead to faster diagnosis and better outcomes. Symptoms may vary in severity from person to person. If you or a loved one are experiencing any of the following, consider speaking with a specialist.
- Progressive muscle weakness and wasting
- Myotonia causing stiff muscles that relax slowly after use
- Facial drooping and weakness affecting chewing and swallowing
- Ptosis and cataracts affecting vision
- Cognitive and behavioral changes
- Cardiac arrhythmias and conduction abnormalities
Who Myotonic Dystrophy Affects
Myotonic Dystrophy Type 1 (DM1) typically appears in adolescence to adulthood, though congenital forms occur in infants. Myotonic Dystrophy Type 2 (DM2) typically appears in adulthood. Affects males and females equally. Autosomal dominant inheritance with anticipation—children often have more severe disease and earlier onset. Occurs across all populations.
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Help Paying for Myotonic Dystrophy Treatment
Charity funds and drugmaker programs for Myotonic Dystrophy, checked at the source. Pick your insurance to see what fits.
- From a charity · Muscular Dystrophy AssociationMDA Durable Medical Equipment (DME) Grant Program fundApply directly
Pays for: Medical equipment (wheelchairs, lifts, canes and other DME), up to $1,000 per year.
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Side Effect Explorer
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Genetic Testing
Genetic testing can confirm a diagnosis, guide treatment decisions, and identify family members who may be at risk.
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Trusted Myotonic Dystrophy Resources
Reputable organizations and medical references for learning more about Myotonic Dystrophy, including disease registries, foundation resources, and clinical guidelines.