Disease Directory Myotonic Dystrophy
Neuromuscular

Myotonic Dystrophy

Also known as: Steinert disease, DM1, dystrophia myotonica

Prevalence

1 in 8,000

Onset

Variable; childhood to adulthood depending on subtype

Type

Autosomal dominant trinucleotide repeat expansion

Gene

DMPK

About Myotonic Dystrophy

Myotonic Dystrophy type 1 (DM1) is the most common adult-onset muscular dystrophy, caused by a CTG trinucleotide repeat expansion in the DMPK gene on chromosome 19q13.3. It is a multisystem disorder affecting skeletal muscle, cardiac muscle, the lens of the eye, and the endocrine and central nervous systems. Disease severity correlates with repeat length, and anticipation — worsening across generations — is a hallmark feature.

Common Clinical Features

Myotonia (delayed muscle relaxation after contraction) Progressive distal muscle weakness and wasting Cardiac conduction defects and arrhythmias Posterior subcapsular cataracts Excessive daytime sleepiness and cognitive involvement Frontal balding and testicular atrophy in males Swallowing difficulties and gastrointestinal dysmotility

Clinical Trial Eligibility Tips

What to know before applying to Myotonic Dystrophy trials.

Trials often require genetic confirmation of CTG repeat length (typically >50 repeats for DM1); have your genetic report ready

Cardiac eligibility screens are common — bring a recent ECG and echocardiogram as conduction defects may be exclusion criteria

Functional outcome measures such as grip strength myometry and the MIRS scale are standard; baseline assessments strengthen eligibility documentation

Patient Resources

Patient Organization

Myotonic Dystrophy Foundation

Visit website ↗

Natural History Registry

MyoCapture Registry

Join registry ↗

Orphanet

European reference resource for rare diseases (ORPHA:273)

View on Orphanet ↗

NORD

National Organization for Rare Disorders

Search NORD ↗

Find recruiting Myotonic Dystrophy trials

Search 500,000+ studies from ClinicalTrials.gov, filtered for Myotonic Dystrophy. Updated daily.

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