Duchenne muscular dystrophy | |
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Microscopic image of cross-sectional calf muscle from a person with Duchenne muscular dystrophy, showing extensive replacement of muscle fibers by fat cells. | |
Pronunciation | |
Specialty | Pediatric neurology, neuromuscular medicine, medical genetics |
Symptoms | Muscle weakness, trouble standing up, scoliosis[2][3][4] |
Usual onset | Around age 4[2] |
Causes | Genetic (X-linked recessive)[3] |
Diagnostic method | Genetic testing[3] |
Treatment | Pharmacological treatment, physical therapy, braces, speech therapy, occupational therapy, surgery, assisted ventilation[2][3] |
Medication | Corticosteroids |
Prognosis | life expectancy: 28–30 years |
Frequency | In males, 1 in 3,500-6,000[3] In females, 1 in 50,000,000[5] |
Duchenne muscular dystrophy (DMD) is a severe type of muscular dystrophy predominantly affecting boys.[3][6][7] The onset of muscle weakness typically begins around age four, with rapid progression.[2] Initially, muscle loss occurs in the thighs and pelvis, extending to the arms,[3] which can lead to difficulties in standing up.[3] By the age of 12, most individuals with Duchenne muscular dystrophy are unable to walk.[2] Affected muscles may appear larger due to an increase in fat content,[3] and scoliosis is common.[3] Some individuals may experience intellectual disability,[3] and females carrying a single copy of the mutated gene may show mild symptoms.[3]
Duchenne muscular dystrophy is caused by mutations and/or deletions in any of the 79 exons encoding the large dystrophin protein, which is essential for maintaining the muscle fiber's cell membrane integrity.[3] The disorder follows an X-linked recessive inheritance pattern, with approximately two-thirds of cases inherited from the mother and one-third resulting from a new mutation.[3] Diagnosis can frequently be made at birth through genetic testing, and elevated creatine kinase levels in the blood are indicative of the condition.[3]
While there is no known cure, management strategies such as physical therapy, braces, and corrective surgery may alleviate symptoms.[2] Assisted ventilation may be required in those with weakness of breathing muscles.[3] Several drugs designed to address the root cause are currently available including gene therapy (Elevidys), and antisense drugs (Ataluren, Eteplirsen etc.).[3] Other medications used include glucocorticoids (Deflazacort, Vamorolone); calcium channel blockers (Diltiazem); to slow skeletal and cardiac muscle degeneration, anticonvulsants to control seizures and some muscle activity, and Histone deacetylase inhibitors (Givinostat) to delay damage to dying muscle cells.[2][3]
Various figures of the occurrence of Duchenne muscular dystrophy are reported. One source reports that it affects about one in 3,500 to 6,000 males at birth.[3] Another source reports Duchenne muscular dystrophy being a rare disease and having an occurrence of 7.1 per 100,000 male births.[8] A number of sources referenced in this article indicate an occurrence of 6 per 100,000.[9]
Duchenne muscular dystrophy is the most common type of muscular dystrophy,[3] with a median life expectancy of 28–30 years.[10][11] However, with comprehensive care, some individuals may live into their 30s or 40s.[3] Duchenne muscular dystrophy is considerably rarer in females, occurring in approximately one in 50,000,000 live female births.[5]
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