Duchenne Muscular Dystrophy (DMD) is a rare and progressive genetic disorder that primarily affects boys. It is characterized by progressive muscle weakness caused by the absence or insufficient production of a protein called dystrophin, which is essential for the integrity of muscle fibers.
This condition is considered one of the most common and severe forms of muscular dystrophy in childhood, affecting about 1 in every 3,500 to 5,000 boys worldwide. Thanks to advances in medicine, patients today are achieving greater life expectancy and quality of life, although there is still no definitive cure.
What is Duchenne Muscular Dystrophy?
DMD is an inherited disease linked to the X chromosome, which explains why it occurs more frequently in boys. Girls can be carriers of the altered gene but rarely develop symptoms, since they usually have a second healthy X chromosome.
In the absence of dystrophin, muscle fibers become fragile and degenerate easily. Over time, this leads to progressive loss of strength, causing difficulties in walking, standing up, or performing daily activities.
Genetic Causes
DMD is caused by mutations in the DMD gene, which is responsible for producing the dystrophin protein. Without dystrophin, muscles cannot adequately regenerate after everyday minor damage, leading to accumulated injuries that compromise their function.
The inheritance pattern is X-linked recessive, meaning the defective gene is located on the X chromosome. Boys who inherit this gene develop the disease, while girls are usually only carriers but can pass it on to their children.
Symptoms of Duchenne Muscular Dystrophy
The first signs of DMD usually appear between ages 2 and 5. Common symptoms include:
Difficulty walking, running, or climbing stairs
Frequent falls
Delayed motor development, such as difficulty starting to walk
Enlarged calves (pseudohypertrophy)
Using the hands to push themselves up from the floor (Gowers’ sign)
Weakness in proximal muscles (thighs, hips, and shoulders)
As the disease progresses, usually by around age 12, many patients lose the ability to walk and become wheelchair-dependent. In advanced stages, respiratory and cardiac muscles are also affected, requiring specialized medical support.
Diagnosis of DMD
Early diagnosis is crucial for improving quality of life and starting supportive treatments as soon as possible. Key exams include:
Blood test (CPK – creatine phosphokinase): elevated levels indicate muscle damage
Genetic testing: confirms mutations in the DMD gene
Muscle biopsy: shows absence or reduction of dystrophin (less commonly used today due to genetic tests)
Imaging exams: help assess the extent of muscle involvement
Treatment of Duchenne Muscular Dystrophy
There is currently no cure for DMD, but several treatments can slow disease progression and improve quality of life:
Corticosteroids (prednisone, deflazacort): reduce inflammation and delay muscle degeneration
Physical therapy and rehabilitation: essential to maintain mobility, prevent contractures, and strengthen remaining muscles
Respiratory therapies: help preserve lung function, especially in advanced stages
Cardiac care: regular monitoring by a cardiologist, since the heart is also a muscle affected by the disease
New medications: innovative therapies, such as exon skipping (which enables partial production of dystrophin), are available in some countries and bring hope to patients
Prognosis
Without treatment, DMD often leads to severe respiratory and cardiac complications in adolescence or early adulthood. However, with medical advances, life expectancy has increased significantly, and many patients now reach adulthood and maintain a more active routine with appropriate support.
Curiosities, Myths, and Scientific Advances in DMD
Myth: “Duchenne Muscular Dystrophy only affects leg muscles.”
In fact, the disease progressively impacts many muscles, including those of the trunk, arms, heart, and respiratory system.Curiosity: The disease was named after French physician Guillaume Duchenne, who first described it in the 19th century.
Scientific advances: Recent studies in gene therapy have shown promising results. Researchers are testing techniques that insert modified versions of the dystrophin gene, along with stem cell therapies and medications that assist in partial protein production. These approaches are still experimental but offer hope for future treatment.
