Myotonic Dystrophy Type 1 (DM1)

Myotonic Dystrophy Type 1 (DM1) is a rare neuromuscular disease that affects multiple organ systems, with symptoms ranging from myotonia (an inability for muscles to relax after flexing) and muscle weakness to cardiac and respiratory dysfunction, excessive sleepiness, and intellectual disability. Between 1 in 10,000 to 100,000 people worldwide are living with DM1, experiencing reduced quality of life and shortened life expectancy.1

DM1 has several forms, which range in age of presentation and severity, including congenital, infantile, juvenile, and adult (classic). The disease affects multiple organ systems and leads to progressive muscle loss and weakness.

The disease is genetically inherited in an autosomal dominant pattern; transcription of the mutated DMPK gene results in the generation of toxic RNA aggregates that accumulate in the nucleus of the cell and trap specific proteins that are critical for normal cellular function in adults.2




Myotonic Dystrophy Type 1 (DM1) image

Not an actual patient

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Community Support & Resources 

Those who would like to learn more about DM1 may find it useful to visit the websites of patient organizations and other groups that provide support for the Rare Disease community. The links below provide access to several but not all of the organizations that serve patients and caregivers in this disease state. Astellas is not affiliated with and does not endorse any of the organizations listed below. The information provided by Astellas is for informational purposes only and is not meant to replace the advice of a healthcare professional.

logoMyotonic Dystrophy Foundation


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1. Bird TD. Myotonic Dystrophy Type 1. 1999 Sep 17 [Updated 2021 Mar 25]. In: Adam MP, Everman DB, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2022; Landfeldt E, et al. J Neurol. 2019; (266) 998-1006; 9. de Die-Smulders CEM, et al. Brain. 1998; (121) 1557-63.
2. Thornton CA, et al. Neurol Clin. 2014; 32(3): 705-19.