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Myotonic dystrophy: Treatment and prognosis

Basil T Darras, MD
David A Chad, MD
Section Editors
Jeremy M Shefner, MD, PhD
Douglas R Nordli, Jr, MD
Stephanie B Jones, MD
Deputy Editor
John F Dashe, MD, PhD


Myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2) are autosomal dominant, multisystem disorders characterized by skeletal muscle weakness and myotonia, cardiac conduction abnormalities, iridescent cataracts, and other abnormalities.

The management and prognosis of patients with myotonic dystrophy will be reviewed here. Other aspects of myotonic dystrophy are discussed separately. (See "Myotonic dystrophy: Etiology, clinical features, and diagnosis".)


The genetics, clinical features, and diagnosis of myotonic dystrophy are reviewed here briefly and discussed in detail elsewhere. (See "Myotonic dystrophy: Etiology, clinical features, and diagnosis".)

DM1 results from an expansion of a CTG trinucleotide repeat in the 3'-untranslated region of the DMPK gene. DM2 is caused by an expansion of a CCTG tetranucleotide repeat located in intron 1 of the ZNF9 (CNBP) gene. (See "Myotonic dystrophy: Etiology, clinical features, and diagnosis", section on 'Genetics'.)

The diagnosis of myotonic dystrophy can usually be made clinically in a patient with the characteristic presentation and a positive family history. Genetic testing for an expanded CTG repeat in the DMPK gene is the gold standard for confirming the diagnosis of DM1. Testing for the CCTG repeat in the ZNF9 (CNBP) gene is appropriate if DM1 testing is negative. (See "Myotonic dystrophy: Etiology, clinical features, and diagnosis", section on 'Diagnosis'.)

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Literature review current through: Nov 2017. | This topic last updated: Oct 12, 2017.
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