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Myotonic Dystrophy (DM)

Childhood-Onset DM1

DM1 begins in early childhood (but not at birth) and typically presents before the age of 10. The first symptoms tend to be more behavioral and cognitive than physical. Intellectual impairment with low IQ is a common manifestation. Some people with childhood-onset DM struggle with attentional deficits, executive dysfunctions, and cognitive and behavioral problems. An "avoidant" or apathetic personality can be part of the picture.15, 16, 17, 18, 19, 20

As the child matures into adulthood, typical features of adult-onset DM1 usually emerge. Serious cardiac rhythm disturbances may occur in asymptomatic adolescents with no or only subtle signs of DM. Sports and physical exercise precipitate arrhythmias in more than 50% of these patients.21, 22

To learn more about the juvenile-onset form of DM1, be sure to read Childhood-Onset DM1 Can Cause Cognitive, Behavior Challenges (part of Quest's In Focus: Myotonic Dystrophy series).


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  2. Day, J. W. et al. Myotonic dystrophy type 2: Molecular, diagnostic and clinical spectrum. Neurology (2003). doi:10.1212/01.WNL.0000054481.84978.F9
  3. Machuca-Tzili, L., Brook, D. & Hilton-Jones, D. Clinical and molecular aspects of the myotonic dystrophies: A review. Muscle and Nerve (2005). doi:10.1002/mus.20301
  4. Vazquez, J. A. et al. Hypothalamic-pituitary-testicular function in 70 patients with myotonic dystrophy. J. Endocrinol. Investig. Off. J. Ital. Soc. Endocrinol. (1990). doi:10.1007/BF03350681
  5. Ørngreen, M. C., Arlien-Søborg, P., Duno, M., Hertz, J. M. & Vissing, J. Endocrine function in 97 patients with myotonic dystrophy type 1. J. Neurol. (2012). doi:10.1007/s00415-011-6277-5
  6. Peric, S. et al. Hypogonadism and erectile dysfunction in myotonic dystrophy type 1. Acta Myol. (2013).
  7. Meola, G. & Moxley, R. T. Myotonic dystrophy type 2 and related myotonic disorders. Journal of Neurology (2004). doi:10.1007/s00415-004-0590-1
  8. Wiles, C. M. et al. Falls and stumbles in myotonic dystrophy. J. Neurol. Neurosurg. Psychiatry (2006). doi:10.1136/jnnp.2005.066258
  9. Ricker, K. et al. Proximal myotonic myopathy: A new dominant disorder with myotonia, muscle weakness, and cataracts. Neurology (1994). doi:doi:10. 1212/WNL.44.8.1448
  10. Udd, B., Krahe, R., Wallgren-Pettersson, C., Falck, B. & Kalimo, H. Proximal myotonic dystrophy - A family with autosomal dominant muscular dystrophy, cataracts, hearing loss and hypogonadism: Heterogeneity of proximal myotonic syndromes? Neuromuscul. Disord. (1997). doi:10.1016/S0960-8966(97)00041-2
  11. Heatwole, C. et al. Patient-Reported Impact of Symptoms in Myotonic Dystrophy Type 2 (PRISM-2). Neurology (2015). doi:10.1212/WNL.0000000000002225
  12. Suokas, K. I., Haanpää, M., Kautiainen, H., Udd, B. & Hietaharju, A. J. Pain in patients with myotonic dystrophy type 2: A postal survey in Finland. Muscle and Nerve (2012). doi:10.1002/mus.22249
  13. George, A., Schneider-Gold, C., Zier, S., Reiners, K. & Sommer, C. Musculoskeletal pain in patients with myotonic dystrophy type 2. Arch. Neurol. (2004). doi:10.1001/archneur.61.12.1938
  14. Gadalla, S. M. et al. Cancer risk among patients with myotonic muscular dystrophy. JAMA - J. Am. Med. Assoc. (2011). doi:10.1001/jama.2011.1796
  15. Meola, G. et al. Executive dysfunction and avoidant personality trait in myotonic dystrophy type 1 (DM-1) and in proximal myotonic myopathy (PROMM/DM-2). Neuromuscul. Disord. (2003). doi:10.1016/S0960-8966(03)00137-8
  16. Udd, B. & Krahe, R. The myotonic dystrophies: Molecular, clinical, and therapeutic challenges. The Lancet Neurology (2012). doi:10.1016/S1474-4422(12)70204-1
  17. Ekström, A. B., Hakenäs-Plate, louise, Tulinius, M. & Wentz, E. Cognition and adaptive skills in myotonic dystrophy type 1: A study of 55 individuals with congenital and childhood forms. Dev. Med. Child Neurol. (2009). doi:10.1111/j.1469-8749.2009.03300.x
  18. Douniol, M. et al. Psychiatric and cognitive phenotype of childhood myotonic dystrophy type 1. Dev. Med. Child Neurol. (2012). doi:10.1111/j.1469-8749.2012.04379.x
  19. Angeard, N. et al. A new window on neurocognitive dysfunction in the childhood form of myotonic dystrophy type 1 (DM1). Neuromuscul. Disord. (2011). doi:10.1016/j.nmd.2011.04.009
  20. Echenne, B. et al. Myotonic dystrophy type I in childhood. Long-term evolution in patients surviving the neonatal period. Eur. J. Paediatr. Neurol. (2008). doi:10.1016/j.ejpn.2007.07.014
  21. Bhakta, D., Lowe, M. R. & Groh, W. J. Prevalence of structural cardiac abnormalities in patients with myotonic dystrophy type I. Am. Heart J. (2004). doi:10.1016/j.ahj.2003.08.008
  22. Bassez, G. et al. Severe cardiac arrhythmias in young patients with myotonic dystrophy type 1. Neurology (2004). doi:10.1212/01.WNL.0000144343.91136.CF
  23. Wesström, G., Bensch, J. & Schollin, J. Congenital myotonic dystrophy. Incidence, clinical aspects and early prognosis. Acta Paediatr. Scand. (1986).
  24. Campbell, C., Levin, S., Siu, V. M., Venance, S. & Jacob, P. Congenital myotonic dystrophy: Canadian population-based surveillance study. J. Pediatr. (2013). doi:10.1016/j.jpeds.2012.12.070
  25. Harley, H. G. et al. Size of the unstable CTG repeat sequence in relation to phenotype and parental transmission in myotonic dystrophy. Am. J. Hum. Genet. (1993).
  26. Whelan, D. T., Carson, N. & Zeesman, S. Paternal transmission of the congenital form of myotonic dystrophy type 1: A new case and review of the literature. Am. J. Med. Genet. (2002). doi:10.1002/ajmg.10141
  27. Darras, B. T. & Volpe, J. J. Muscle Involvement and Restricted Disorders. in Volpe’s Neurology of the Newborn (2017). doi:10.1016/B978-0-323-42876-7.00033-8

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