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Myotonic Dystrophy (DM)

Congenital DM1

Estimates of the incidence of congenital DM vary widely, ranging from about 2 to 28 per 100,000 live births in different studies.23, 24 When DM symptoms manifest at birth, life-threatening complications ensue. However, once this critical period is past, improvement is likely during early childhood. Later, as a child approaches adolescence, it is likely that the symptoms of adult-onset DM1 will appear.

Congenital DM has been observed only in DM1. To learn more, see Energy, Dedication, Hope Help Parents of Children with Congenital DM1, part of Quest's In Focus: Myotonic Dystrophy series.

When a child is born with congenital DM1, the mother usually has adult-onset DM1, even though her symptoms may be so mild that she did not know she had the disorder. Mothers with DM also can pass on the adult-onset form. A child can inherit the disease from the father, but it is almost always the adult-onset form. These unusual features are not seen in other genetic disorders.25, 26 For more, see Causes/Inheritance.

Respiratory involvement is common and is the leading cause of death in the neonatal period. Mechanical ventilation is required for 70% to 80% or more of patients.27, 24 Feeding difficulties are also common, with many children requiring a nasogastric or gastric feeding tube. Both sucking and swallowing are related to muscle weakness in the face and the throat area.

The overall mortality rate is approximately 15% to 20% percent and approaches 40% in severely affected infants.27

Cognitive disabilities in congenital DM

Infants born with congenital DM often have serious cognitive disabilities, although this is not always the case. Intellectual disability is present in 50% to 60% of the children who survive.27 The condition seems to be related to abnormal development of parts of the brain, presumably caused by genetic abnormalities.

Some experts have suggested that the very high incidence of labor and delivery complications in mothers with DM also could be a contributing factor to the cognitive problems seen in these babies.

Outgrowing congenital DM

Cognitive difficulties do not improve but they generally do not worsen, either, and children can learn when given the right tools, instruction, and environment. See Medical Management. However, despite early gains during childhood, children with congenital DM will very likely develop the adult form of DM when they reach adolescence or adulthood.

Speech, hearing and vision difficulties

The muscles involved in talking often are affected in congenital DM. Hearing also can be impaired. The eye muscles are affected and are not always aligned, a condition called strabismus.

Cataracts, common in adult-onset DM, are not a feature of congenital DM during early childhood. However, children with congenital DM are likely to develop them later.2

Weak muscles

Babies with congenital DM1 have very weak muscles and a lack of muscle tone (hypotonia) rather than myotonia. They appear floppy, have trouble breathing, and suck and swallow poorly.

In the past, many infants with congenital DM did not survive. Today, with special care in neonatal intensive care units, such children have a much better chance of survival, although they still will face multiple challenges in childhood.

Babies with congenital DM1 often are born with clubfeet, a curvature of the feet and lower legs. The problem may be due to abnormal muscle development in the lower legs and feet during fetal life.

Infants with DM1 do not have myotonia at first but develop it later in life.27

References

  1. Turner, C. & Hilton-Jones, D. Myotonic dystrophy: Diagnosis, management and new therapies. Current Opinion in Neurology (2014). doi:10.1097/WCO.0000000000000128
  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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