Duchenne Muscular Dystrophy (DMD)


The term muscular dystrophy encompasses a group of genetic diseases characterized by progressive muscle weakness and wasting. There are different types of muscular dystrophy depending on genetic etiology. These include Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), congenital muscular dystrophy, facioscapulohumeral muscular dystrophy (FSHD), limb-girdle muscular dystrophy (LGMD), Emery-Dreifuss muscular dystrophy, oculopharyngeal muscular dystrophy (OPMD), and myotonic muscular dystrophy.1 

As a whole, muscular dystrophies are estimated to affect 250,000 people in the US.2

According to a systematic literature review of studies published between 1960 and 2013, the total combined prevalence for all muscular dystrophies ranged from 19.8 to 25.1 per 100,000 person-years.3

Prevalence by Muscular Dystrophy Type

According to the literature review, the most common types of muscular dystrophy are myotonic dystrophy, with a prevalence ranging between 0.5 and 18.1 per 100,000, DMD with a prevalence of 1.7 and 4.2 per 100,000, and FSHD, with a prevalence between 3.2 and 4.6 per 100,000.3 

This was followed by BMD with a prevalence between 0.4 and 2.6 per 100,000, LGMD with a prevalence between 0.9 and 2.3 per 100,000, congenital muscular dystrophy with a prevalence of 0.6 per 100,000, Emery-Dreifuss muscular dystrophy with a prevalence between 0.1 and 0.4 per 100,000, and OPMD with a prevalence of 0.1 per 100.000.

These findings indicate that the overall rate for muscular dystrophy is lower than other conditions such as multiple sclerosis (MS), which has an average prevalence of 67.83 per 100,000 but higher than that of hereditary cerebellar ataxias, which have a prevalence of 2.7 per 100,000.

The prevalence of different types of muscular dystrophy also varied by country. For example, the prevalence of DMD per 100,000 people was 1.7 in Canada, 1.2 in Russia, 5.7 in Japan, 7.7 in Egypt, 1 in South Africa, 6 in Libya, between 1.7 and 3.4 in Italy, 2.9 in Slovenia, and between 3.5 and 4.3 in the UK.

These differences could be due to the differences between the epidemiological methods used and parameters for case inclusion. They could also be caused by differences in population dispositions between different populations.

A Closer Look at Duchenne and Becker Muscular Dystrophies

According to data from the muscular dystrophy surveillance tracking and research network (MD STARnet), the estimated prevalence of Duchenne and Becker muscular dystrophies was 1 in 7250 males aged 5 to 24 in the US in 2010.4 The total number of DMD patients in Arizona, Colorado, Georgia, Iowa, and Western New York Counties was 735 between 1982-2011. This number was 106 for BMD.5

As of December 31, 2011, 33 patients were less than age 5, 184 were between ages 5 and 12, 217 were between ages 12 and 18, and 262 were age 18 and above in all MD STARnet sites.

In terms of race and ethnicity, 501 patients were of non-Hispanic white origin, 55 were of non-Hispanic black origin, 175 were of Hispanic origin, and 110 were of other racial and ethnic origins.

By the end of 2007 more than 8 in 10 males with Duchenne or Becker muscular dystrophies who were born 15 to 19 years earlier were still alive, while only 6 in 10 who were born 20 to 24 years earlier were still living.6

According to a 2020 study on the global epidemiology of DMD, the pooled global DMD prevalence was 7.1 cases per 100,000 males and 2.8 cases per 100,000 in the general population. The pooled global DMD birth prevalence was 19.8 per 100,000 live male births.7

The Value of Prevalence Information

Accurate information on the prevalence of muscular dystrophy can ensure that information, resources, and services are available to patients and families, as well as healthcare professionals. It can also ensure that the needs of patients with different types of muscular dystrophy are met in the appropriate way.

The Relationship Between Prevalence and Incidence

According to a study by researchers at the Deerfield Institute, while the incidence of DMD remained stable, the prevalence of the disease increased. This could be attributed to better treatments and care and increased longevity.8  

The study estimated the diagnosed incidence of DMD in the US at 17.24 per 100,000 live male births in 2019. This corresponds to about 362 cases in that year. The diagnosed prevalence of the disease was 6.09 per 100,000 males across all age groups. This corresponds to about 10,015 cases.

According to the study, 64.5% of patients were under age 20. The prevalence of DMD among males aged 45 years or less was 10 per 100,000.

References

  1. Muscular dystrophy: hope through research. National Institute of Neurological Disorders and Stroke. Updated February 25, 2021. Accessed May 28, 2021.
  2. Duchenne muscular dystrophy. National Organization for Rare Disorders. Accessed May 28. 2021.
  3. Theadom T, Rodrigues M, Roxburgh R, et al. Prevalence of muscular dystrophies: a systematic literature review. Neuroepidemiology. 2014;43(3-4):259-268. doi:10.1159/000369343
  4. MD STARnet data and statistics. Centers for Disease Control and Prevention. Updated October 27, 2020. Accessed June 22, 2021.
  5. Mathews KD, Cunniff C, Kantamneni JR, et al. Muscular dystrophy surveillance tracking and research network (MD STARnet): case definition in surveillance for childhood-onset Duchenne/Becker muscular dystrophy. J Child Neurol. 2010; 25(9):1098–1102. doi:10.1177/0883073810371001 
  6. Centers for Disease Control and Prevention (CDC). Prevalence of Duchenne/Becker muscular dystrophy among males aged 5-24 years – four states, 2007. Morbidity and Mortality Weekly Report. 2009;58(40):1119-1122.
  7. Crisafulli S, Sultana J, Fontana A, Salvo F, Messina S, Trifirò G. Global epidemiology of Duchenne muscular dystrophy: an updated systematic review and meta-analysis. Orphanet J Rare Dis. 2020;5;15(1):141. doi:10.1186/s13023-020-01430-8
  8. Giegerich E, Stuntz M. PMS30 Duchenne muscular dystrophy prevalence in the US: a novel incidence based modeling approach using system dynamics. Value Health. 2019;22(SUP 2);S244. doi:10.1016/j.jval.2019.04.1140

Article reviewed by Eleni Fitsiou, MD, on July 1, 2021.

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