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Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Pediatr. Nov 8, 2015; 4(4): 66-80
Published online Nov 8, 2015. doi: 10.5409/wjcp.v4.i4.66
Congenital and childhood myotonic dystrophy: Current aspects of disease and future directions
Genevieve Ho, Michael Cardamone, Michelle Farrar
Genevieve Ho, Michael Cardamone, Michelle Farrar, Discipline of Paediatrics, School of Women’s and Children’s Health, UNSW Medicine, the University of New South Wales, Sydney NSW 2031, Australia
Michael Cardamone, Michelle Farrar, Department of Neurology, Sydney Children’s Hospital, Randwick NSW 2031, Australia
Author contributions: Ho G contributed to literature searches and initial drafting and revision of the manuscript; Farrar M contributed to initial outline and revisions of the manuscript; Cardamone M contributed to revising the manuscript.
Conflict-of-interest statement: Ms Ho, Dr. Cardamone and Dr. Farrar report no disclosures or conflict of interests.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Dr. Michelle Farrar, MBBS, FRACP, PhD, Department of Neurology, Sydney Children’s Hospital, High St, Randwick NSW 2031, Australia. m.farrar@unsw.edu.au
Telephone: +61-2-93821549 Fax: +61-2-93821580
Received: May 20, 2015
Peer-review started: May 20, 2015
First decision: August 4, 2015
Revised: August 7, 2015
Accepted: September 25, 2015
Article in press: September 28, 2015
Published online: November 8, 2015
Processing time: 174 Days and 2.7 Hours
Abstract

Myotonic dystrophy type 1 (DM1) is multisystem disease arising from mutant CTG expansion in the non-translating region of the dystrophia myotonica protein kinase gene. While DM1 is the most common adult muscular dystrophy, with a worldwide prevalence of one in eight thousand, age of onset varies from before birth to adulthood. There is a broad spectrum of clinical severity, ranging from mild to severe, which correlates with number of DNA repeats. Importantly, the early clinical manifestations and management in congenital and childhood DM1 differ from classic adult DM1. In neonates and children, DM1 predominantly affects muscle strength, cognition, respiratory, central nervous and gastrointestinal systems. Sleep disorders are often under recognised yet a significant morbidity. No effective disease modifying treatment is currently available and neonates and children with DM1 may experience severe physical and intellectual disability, which may be life limiting in the most severe forms. Management is currently supportive, incorporating regular surveillance and treatment of manifestations. Novel therapies, which target the gene and the pathogenic mechanism of abnormal splicing are emerging. Genetic counselling is critical in this autosomal dominant genetic disease with variable penetrance and potential maternal anticipation, as is assisting with family planning and undertaking cascade testing to instigate health surveillance in affected family members. This review incorporates discussion of the clinical manifestations and management of congenital and childhood DM1, with a particular focus on hypersomnolence and sleep disorders. In addition, the molecular genetics, mechanisms of disease pathogenesis and development of novel treatment strategies in DM1 will be summarised.

Keywords: Clinical manifestations; Myotonic dystrophy type 1; Childhood myotonic dystrophy; Congenital myotonic dystrophy; Natural history; Management

Core tip: Type 1 myotonic dystrophy is an often undetected neuromuscular disease in paediatric patients with variable clinical manifestations and burden of disease. We review the current understandings of disease pathogenesis, symptoms and management in congenital and childhood myotonic dystrophy with a particular focus on hypersomnolence and sleep disorders. Future directions should target standardised care and regular surveillance, understanding pathophysiology and new treatment strategies.