DUCHENNES MUSCULAR DYSTROPHY

Duchenne muscular dystrophy (DMD) is a severe, rare, and progressive muscle disease that almost exclusively affects boys. The disease is caused by a genetic defect in the muscle cells, leading to gradual loss of muscle function.^1,2

Facts about DMD in the Nordics

DMD affects
1 in 5000 - 6000
live male births.

In the Nordics, between
25 - 30 boys are diagnosed
with DMD annually.

In total, there are approximately
between 700-750 diagnosed
DMD patients in the Nordics.

FAQ

Is Duchenne muscular dystrophy inherited?

Roughly two-thirds of cases are inherited, while approximately one-third of cases occur spontaneously. The fact that almost only boys are affected is because they have only one X chromosome, and it is on the X chromosome that the disease-causing mutation is found.
Girls, who have two X chromosomes, are therefore protected by the healthy gene.^1-3.

How common is DMD in the Nordics?

DMD affects 1 in 5000-6000 live male births.² In the Nordics, 25-30 boys are diagnosed with DMD annually.^1,3,4,5 In total, there are approximately between 700-750 diagnosed DMD patients in the Nordics.^4-7

What causes DMD?

The disease is caused by a genetic alteration (mutation) in the dystrophin gene (DMD gene). The mutation leads to a deficient production of the protein dystrophin, which is necessary for the structure of muscle cells. This results in the breakdown of muscle cells over time.^1-3

What are the symptoms of DMD?

The symptoms of Duchenne muscular dystrophy typically manifest around the time a child begins walking and include muscle weakness, difficulty running, and jumping. Stiff muscles and muscle cramps may also occur.
Other early signs may include enlarged calf muscles and noticeable curvature of the lower back.¹

How is DMD diagnosed?

When Duchenne muscular dystrophy (DMD) is suspected, the usual procedure involves measuring the level of the enzyme creatine kinase (CK) in the blood. If symptoms are present along with elevated CK levels, the diagnosis can be confirmed through DNA analysis. Sometimes, a muscle biopsy is also performed to differentiate between DMD and the milder variant, Becker muscular dystrophy.^1,2

How is DMD treated?

Currently, there is no cure for DMD, but various treatments can help alleviate symptoms and improve the quality of life for those affected. Thanks to medical advancements, the average lifespan for DMD patients has also increased. Previously, children were estimated to live until the end of their teenage years; however, today an increasing number of patients are living beyond 40 years old. Corticosteroids are often used to improve muscle strength and extend the period during which children can walk.
Other treatment options include medications to prevent complications and alleviate symptoms. Providing the best possible care for DMD patients requires a comprehensive interdisciplinary treatment and support structure. Both primary and specialist care, including rehabilitation services, are crucial providers of care.^1,2

Future research?

Intensive clinical research is underway worldwide to develop new therapies for Duchenne muscular dystrophy. One strategy among these therapies is to restore deficient dystrophin levels. Examples of such therapies include stem cell transplantation, gene therapy, and exon-skipping. Another treatment strategy is to reduce the negative effects that occur as a result of dystrophin deficiency. Traditionally, this has involved treatment with corticosteroids, but research is also underway in other areas, such as inhibition of the enzyme histone deacetylase (HDAC). The goal is to slow down the inflammatory process that leads to muscle cells being converted into connective and fatty tissue. The hope is that these new therapies will be able to slow the progression of the disease and improve the quality of life for patients with DMD.²

References

1. Socialstyrelsen (2024) Duchennes muskeldystrofi, Socialstyrelsen. Available at: https://www.socialstyrelsen.se/kunskapsstod-och-regler/omraden/sallsynta-halsotillstand/duchennes-muskeldystrofi/ (Accessed: 17 April 2024).

2.Duan, D. et al. (2021) ‘Duchenne muscular dystrophy’, Nature Reviews Disease Primers, 7(1), pp. 1–19. Available at: https://doi.org/10.1038/s41572-021-00248-3.

3. Annexstad, E.J. et al. (2019) ‘Molecular and Clinical Characteristics of a National Cohort of Paediatric Duchenne Muscular Dystrophy Patients in Norway’, Journal of Neuromuscular Diseases, 6(3), pp. 349–359. Available at: https://doi.org/10.3233/JND-190402.

4. Kyttala, M. et al. (2023) ‘RWD 131 A Nationwide Feasibility Study and Study Concept to Assess the Burden of Duchenne Muscular Dystrophy (dmd) in Finland’, Value in Health, 26(12), pp. S529–S529. Available at: https://doi.org/10.1016/j.jval.2023.09.2848.

5. Rudolfsen, J.H. et al. (2024) ‘Burden of Disease of Duchenne Muscular Dystrophy in Denmark – A National Register-Based Study of Individuals with Duchenne Muscular Dystrophy and their Closest Relatives’, Journal of Neuromuscular Diseases, 11(2), pp. 443–457. Available at: https://doi.org/10.3233/JND-230133.

6. Swedish National Registry of Neuromuscular Diseases (2024). NMiS [Registry Data] https://www.neuroreg.se/neuromuskulara-sjukdomar-nmis/statistik/ (Accessed: 6 May 2024)

7. Norwegian Registry for Hereditary and Congenital Neuromuscular Disease (2022). NORNMD – tidl. Muskelregisteret [Registry Data] https://www.unn.no/fag-og-forskning/medisinske-kvalitetsregistre/norsk-register-for-arvelige-og-medfodte-nevromuskulere-sykdommer (Accessed 6 May 2024)

DK-ITFRD-24-00007 September 2024