Myotonic Muscular Dystrophies

Nicholas E. Johnson, MD, MSc, FAAN Muscle and Neuromuscular Junction Disorders p. 1682-1695 December 2019, Vol.25, No.6 doi: 10.1212/CON.0000000000000793
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PURPOSE OF REVIEW This article describes the clinical features, pathogenesis, prevalence, diagnosis, and management of myotonic dystrophy type 1 and myotonic dystrophy type 2.

RECENT FINDINGS The prevalence of myotonic dystrophy type 1 is better understood than the prevalence of myotonic dystrophy type 2, and new evidence indicates that the risk of cancer is increased in patients with the myotonic dystrophies. In addition, descriptions of the clinical symptoms and relative risks of comorbidities such as cardiac arrhythmias associated with myotonic dystrophy type 1 have been improved.

SUMMARY Myotonic dystrophy type 1 and myotonic dystrophy type 2 are both characterized by progressive muscle weakness, early-onset cataracts, and myotonia. However, both disorders have multisystem manifestations that require a comprehensive management plan. While no disease-modifying therapies have yet been identified, advances in therapeutic development have a promising future.

Address correspondence to Dr Nicholas E. Johnson, Virginia Commonwealth University, 1101 E Marshall St, PO Box 980599, Richmond, VA 23298, [email protected].

RELATIONSHIP DISCLOSURE: Dr Johnson has served as a consultant for AMO Pharma; Asklepios BioPharmaceutical, Inc (AskBio); AveXis, Inc; Dyne Therapeutics; Fulcrum Therapeutics; ML Bio; and Vertex Pharmaceuticals Incorporated and has received personal compensation for speaking engagements from Sarepta Therapeutics and Strongbridge Biopharma plc. Dr Johnson has received research/grant support from AMO Pharma; AveXis, Inc; the Coalition to Cure Calpain 3; CSL Behring; Fulcrum Therapeutics; the Muscular Dystrophy Association; the Myotonic Dystrophy Foundation; the National Institute of Neurological Disorders and Stroke (K23NS091511-05; R01NS104010-01); Sarepta Therapeutics; and the US Food and Drug Administration (1RO1FD006071-02). Dr Johnson has received publishing royalties from the Charcot-Marie-Tooth Health Index and the Congenital and Childhood Myotonic Dystrophy Health Index.

UNLABELED USE OF PRODUCTS/INVESTIGATIONAL USE DISCLOSURE: Dr Johnson discusses the unlabeled/investigational use of mexiletine for the treatment of myotonia and armodafinil and modafinil for the treatment of daytime sleepiness in myotonic dystrophy.

© 2019 American Academy of Neurology.