Young patient flexing his muscles

Duchenne Muscular
Dystrophy (DMD)

Duchenne muscular dystrophy (DMD) is rare, but it is the most common form of muscular dystrophy. It results in progressive muscle weakness, starting at a young age.1,2 DMD is a genetic disorder that primarily affects boys. It is characterized by loss of the protein dystrophin in muscle cells due to genetic mutations in the dystrophin gene.3,4 DMD occurs 1 in 4000 live male births, and it has a prevalence of about 11,000 to 13,000 patients in the US.
In patients with DMD, inflammatory changes in the muscle, damage to the muscle cell membrane, and uncontrolled flow of calcium ions result in compromised muscle function.5 Over time, this damage leads to progressive muscle weakness and loss of muscle tissue, including a decline in skeletal, respiratory, and cardiac muscle function.4,5

Treatment with corticosteroids and supportive care is the current standard of care for treating DMD6,7,8; however, chronic corticosteroid treatment is associated with a significant burden of adverse effects. While variable among DMD patients, the significant stages in the disease course are the inability to ambulate independently, the inability to feed oneself, respiratory insufficiency requiring assisted ventilation, and cardiomyopathy. DMD reduces life expectancy to before the fourth decade due to respiratory and/or cardiac failure.

Icon of a stethoscope
Icon of a stethoscope

Symptoms

In the early stages of DMD, generalized muscle weakness in the arms and legs, especially in the proximal muscle groups (such as the hip muscles and the shoulder muscles), is most prominent. Boys with DMD are usually “late walkers” (after 14 months of age).

In young boys, the first sign of the disease is the presence of large calves (calf pseudohypertrophy), accompanied by elevated levels of creatinine kinase (CK). Some infants may present with delayed motor milestones. Patients with DMD may find it difficult to get up from the floor (also known as Gower’s sign), climb up steps, or run. Usually by age 12, most DMD patients begin using a wheelchair.9 In the late stages of DMD, patients lose their ability to walk independently (loss of ambulation), feed themselves, and breath normally (respiratory insufficiency), and they also develop heart dysfunction (cardiomyopathy).

Icon of a magnifying glass
Icon of a magnifying glass

Diagnosis

A diagnosis of DMD is initially suspected based on signs and symptoms in the presenting male child. Clinical symptoms during a physical examination, the pattern of muscle weakness, and family history are critical in this process.

Typically, electromyography reveals a myopathic pattern, and laboratory evaluation shows elevated creatine kinase (CK) levels. While the absence of dystrophin protein may be demonstrated by muscle biopsy-based evaluation, definitive diagnosis is made by dystrophin gene testing.

Icon of a medical treatment bag
Icon of a medical treatment bag

Treatment

Currently, corticosteroids are the mainstay of pharmacologic treatment in DMD. While chronic treatment with corticosteroids is associated with many adverse effects, it has been shown to delay the loss of ambulation. A DMD gene therapy was recently approved for the treatment of DMD in a select age group of patients.10

References:

  1. Mendell JR, Lloyd-Puryear M. Report of MDA muscle disease symposium on newborn screening for Duchenne muscular dystrophy. Muscle Nerve. 2013;48:21-26. doi:10.1002/mus.23810
  2. Passamano L, Taglia A, Palladino A, et al. Improvement of survival in Duchenne Muscular Dystrophy: retrospective analysis of 835 patients. Acta Myol. 2012;31:121-125.
  3. Muscular Dystrophy Association, Duchenne muscular dystrophy (DMD). Accessed July 2023.
  4. Bushby K, Finkel R, Birnkrant DJ, et al. Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and pharmacological and psychosocial management. Lancet Neurol. 2010;9:77-93. doi:10.1016/S1474-4422(09)70271-6
  5. Timpani CA, Hayes A, Rybalka E. Revisiting the dystrophin-ATP connection: How half a century of research still implicates mitochondrial dysfunction in Duchenne Muscular Dystrophy aetiology. Med Hypotheses. 2015;85:1021-1033.
  6. Birnkrant D, Bushby K, Bann CM, et al. Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and neuromuscular, rehabilitation, endocrine, and gastrointestinal and nutritional management. Lancet Neurol. 2018;17(3):251-267. doi:10.1016/S1474-4422(18)30024-3
  7. Birnkrant D, Bushby K, Bann CM, et al. Diagnosis and management of Duchenne muscular dystrophy, part 2: respiratory, cardiac, bone health, and orthopaedic management. Lancet Neurol. 2018;17(4):347-361. doi:10.1016/S1474-4422(18)30025-5
  8. Birnkrant D, Bushby K, Bann CM, et al. Diagnosis and management of Duchenne muscular dystrophy, part 3: primary care, emergency management, psychosocial care, and transitions of care across the lifespan. Lancet Neurol. 2018;17(5)445-455. doi:10.1016/S1474-4422(18)30026-7
  9. Henricson EK, Abresch RT, Cnaan A, et al. The cooperative international neuromuscular research group Duchenne natural history study: glucocorticoid treatment preserves clinically meaningful functional milestones and reduces rate of disease progression as measured by manual muscle testing and other commonly used clinical trial outcome measures. Muscle Nerve. 2013;48(1):55-67. doi:10.1002/mus.23808
  10. FDA Approves First Gene Therapy for Treatment of Certain Patients with Duchenne Muscular Dystrophy. News release. FDA. June 22, 2023. Accessed November 20, 2025. https://www.fda.gov/news-events/press-announcements/fda-approves-first-gene-therapy-treatment-certain-patients-duchenne-muscular-dystrophy

When considering treatment options, which are limited, patients with DMD should consult with a board-certified pediatric or adult neurologist/physiatrist, preferably one who specializes in evaluation and treatment of neuromuscular diseases. All information contained on the Catalystpharma.com website is intended for informational and educational purposes. The information provided on this website is not intended to be a replacement or substitute for professional medical advice. Any information that you have received from Catalystpharma.com should be verified with your licensed healthcare provider. Individuals should never disregard or delay seeking medical advice due to the content of this site.

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