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Our Focus:
Myotonic Dystrophy Type 1 (DM1)
We support all people, families and caregivers living with rare diseases, this Rare Disease Day and every day

Myotonic dystrophy type 1 (DM1) is a rare, genetic, progressive muscle disease distinguished by myotonia. People living with DM1 typically experience progressive weakness of major muscle groups, which can affect mobility, breathing, heart function, speech, digestion, vision, and cognition. The severity of symptoms and pace of progression varies. There are currently no disease-modifying therapies approved to treat DM1.

Each person living with DM1 has a unique and powerful story to tell

Living with DM1 profoundly impacts every part of people’s lives, from work and socializing to family life. Community members have shared their moving perspectives with our team, including what it would mean to them to have a potentially transformative therapy for their disease.

Meet Sarah

Meet Sarah

Sarah shares the impact DM1 has on her and her family and why a potentially transformative therapy is urgently needed

BillyDean and Suzette photo

Meet BillyDean and Suzette

Through their resilience and Suzette’s incredible advocacy efforts for her son, BillyDean, they succeeded in getting a DM1 diagnosis and have been learning how to live and thrive ever since

Joachim Boekelmann photo

Meet Joachim and Tim

Joachim and Tim share their personal stories on living with DM1

Joachim Boekelmann photo

Meet Joachim

“I’m not alone in this:”
One person’s journey with DM1

Loraine Dressler photo

Meet Loraine

A courageous family battle and devotion in the face of generational adversity

About Myotonic Dystrophy Type 1 (DM1)


Symptoms can begin at any point in an affected person’s life, depending on the DM1 subtype. Adult-onset DM1 symptoms typically appear in early teens to 50 years of age.


The underlying cause of DM1 is a defective DMPK gene that encodes a mutated RNA. DM1 is known as a triplet repeat disease because of the expanded number of CTG repeats in the DMPK gene. These CTG repeats cause toxic RNA to cluster in the nucleus. The toxic RNA binds to RNA splicing proteins, causing altered splicing events in many other genes. This altered splicing results in a wide range of disease symptoms and contributes to the significant disease burden.


People experience a broad spectrum of symptoms, including:

  • Muscle weakness throughout the body, from difficulties with facial and swallowing muscles to hand and grip weakness to lower leg and foot weakness, foot drop and resulting mobility issues
  • Myotonia, or difficulty relaxing muscles in the jaw, tongue, throat muscles, lower arm and hand
  • Respiratory issues
  • Gastrointestinal dysfunction throughout the GI tract
  • Cognitive deficits, excessive daytime sleepiness and dysregulated sleep
  • Early cataracts


There are currently no disease-modifying treatments for DM1.


For more information about myotonic dystrophy, see these additional resources*:

*Viewing these links requires you to leave Dyne’s website. Dyne assumes no responsibility for the information, statements or other content you may encounter outside of Dyne’s website.

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