Muscular Dystrophy

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Muscular dystrophy (MD) refers to a group of inherited genetic disorders that cause progressive muscle weakness and degeneration. These conditions affect the muscles' ability to function, and over time, they can lead to disability. The severity and progression of the disease depend on the specific type of muscular dystrophy.

Signs & Symptoms

The symptoms of muscular dystrophy can vary greatly depending on the type, but common symptoms include:

  1. Progressive muscle weakness:

    • The hallmark of all forms of MD, starting typically in childhood or adolescence, but it can also affect adults.

  2. Muscle wasting:

    • Loss of muscle mass and the inability to perform certain movements like running, jumping, or walking.

  3. Difficulty with mobility:

    • Affected individuals may struggle with balance, coordination, and walking, leading to the need for mobility aids as the disease progresses.

  4. Cardiac and respiratory issues:

    • Certain types of MD can affect the heart muscles and breathing muscles, leading to complications such as heart failure or respiratory failure.

  5. Scoliosis or joint contractures:

    • Abnormal curvature of the spine or stiffness in the joints as the muscles weaken and deform.

Anatomy Affected

  1. Muscles:

    • Muscular dystrophy primarily affects the skeletal muscles, which are responsible for movement. These muscles progressively weaken and lose function.

  2. Cardiac muscles:

    • Some types of MD, such as Duchenne MD, can also affect the heart muscle, leading to cardiomyopathy and other heart-related problems.

  3. Respiratory muscles:

    • The diaphragm and intercostal muscles can be impacted, leading to difficulty breathing as the disease advances.

Causes/Transmission

Muscular dystrophy is caused by mutations in the genes responsible for producing proteins that help maintain muscle integrity. These genetic mutations are inherited and passed down through families, although some types of MD can arise spontaneously.

  1. X-linked inheritance:

    • Duchenne and Becker muscular dystrophies are typically inherited in an X-linked recessive pattern, meaning the disease mainly affects males, who inherit the mutated gene from their mothers.

  2. Autosomal inheritance:

    • Other forms, like limb-girdle muscular dystrophy or facioscapulohumeral muscular dystrophy, follow an autosomal dominant or recessive inheritance pattern.

  3. Genetic mutations:

    • The mutations interfere with the production of muscle proteins such as dystrophin (in Duchenne MD), which is critical for muscle cell function.

Treatments

Although there is no cure for muscular dystrophy, treatments focus on managing symptoms and improving quality of life:

  1. Physical therapy:

    • Regular exercise and stretching can help maintain muscle strength and flexibility and delay joint contractures.

  2. Medications:

    • Corticosteroids (e.g., prednisone) are often used to slow muscle degeneration in some types of MD.
    • Medications such as ataluren for Duchenne MD aim to help the body produce more dystrophin.

  3. Surgical interventions:

    • Surgery may be required to correct scoliosis or contractures, or in severe cases, joint replacements.

  4. Ventilatory support:

    • For individuals with respiratory involvement, mechanical ventilation may become necessary to assist with breathing.

  5. Heart medications:

    • If the heart is affected, medications to manage heart failure or cardiomyopathy may be prescribed.

Prevention

Since MD is a genetic condition, it cannot be prevented. However, genetic counseling is recommended for families with a history of muscular dystrophy to understand the risks of inheritance. Early diagnosis and intervention through regular monitoring and therapy can help manage the condition and improve quality of life.

Prognosis/Outlook

The prognosis for muscular dystrophy varies depending on the type and the severity of the symptoms:

  1. Duchenne muscular dystrophy (DMD):

    • DMD is the most severe and progresses quickly, often leading to wheelchair dependence by early adolescence and a shortened lifespan due to heart or respiratory complications.

  2. Becker muscular dystrophy:

    • Symptoms progress more slowly than in Duchenne MD, and affected individuals often have a normal life expectancy.

  3. Facioscapulohumeral and limb-girdle dystrophies:

    • These forms tend to progress more slowly and may allow individuals to maintain some degree of independence throughout life.

  4. Mortality rate:

    • Mortality rates vary depending on the type of MD, with respiratory and cardiac failure being the most common causes of death, especially in the more severe forms like Duchenne MD.

Early diagnosis and consistent management can help individuals with muscular dystrophy live fuller lives with improved mobility, although the disease remains progressive. Research into gene therapy and new medications continues to offer hope for better treatments and potentially even a cure in the future.

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