Muscular Dystrophy

Overview

Muscular dystrophy describes a group of inherited diseases in which voluntary muscles which control movement progressively weaken. In some forms of this disease, the heart and other organs are also affected.

The nine major forms of muscular dystrophy include:
  • Duchenne
  • Becker
  • Myotonic
  • Limb-girdle
  • Facioscapulohumeral
  • Congenital
  • Oculopharyngeal
  • Distal
  • Emery-Dreifuss

Symptoms

Some patients with muscular dystrophy enjoy a normal life span with mild symptoms that progress very slowly. Other patients experience fast, severe muscle weakness and die in their late teens to early twenties.
Symptoms vary depending on the forms of muscular dystrophy:

  • Duchenne is the most common form of muscular dystrophy in children, and causes muscles to decrease in size and grow weaker over time. In most cases, the arms, legs and spine become progressively deformed. Some patients exhibit mild intellectual disability.In the later stages of the disease, patients experience breathing and heart problems and usually die in their late teens or early twenties.
  • Becker is a form of muscular dystrophy similar to Duchenne. But symptoms are milder, appear later in life and progress more slowly. Patients typically live longer than those with other forms of muscular dystophy and retain muscle control further into adulthood.
  • Myotonic, (also called MMD or Steinert's disease refers to a symptom called myotonia, which means prolonged spasm or stiffening of muscles after use. The disease causes muscle weakness and affects the central nervous system, heart, gastrointestinal tract, eyes and hormone-producing glands. Patients have a decreased life expectancy, but daily living is usually not restricted for many years.
  • Limb-girdle causes progressive weakness that begins in the hips and moves to the shoulders, arms and legs. In later stages of the disease, patients find walking difficult or impossible.
  • Facioscapulohumeral affects the muscles that move the face, shoulder blade and upper arm bone. This form of muscular dystrophy progresses slowly, with short periods of rapid muscle deterioration and weakness. Symptoms may also affect a patient’s ability to walk, chew, swallow and speak. This form of muscular dystrophy can vary from mild to completely disabling.
  • Congenital muscular dystrophies are present at birth and progress slowly, causing muscle weakness at birth or in the first few months of life, along with severe shortening or shrinking of muscles, resulting in joint problems. Abnormalities in the brain and seizures may also occur.
  • Oculopharyngeal causes weakness in the eye and face muscles, which may lead to difficulty swallowing. Weakness in pelvic and shoulder muscles may occur as a later symptom.
  • Distal causes weakness and wasting of the muscles in the forearms, hands, lower legs and feet. It is generally less severe, progresses more slowly and affects fewer muscles than other forms of muscular dystrophy.
  • Emery-Dreifuss causes muscle weakness and wasting in the shoulders, upper arms and lower legs. Life-threatening heart problems are also common. Other symptoms include muscle shortening and weakness that can spread to chest and pelvic muscles. The disease progresses slowly and causes less severe muscle weakness than some other forms of muscular dystrophy.

Causes

The type of muscular dystrophy a patient is diagnosed with depends on which gene is defective. Most muscular dystrophies are a form of inherited disease that mothers (called X-linked disorders), who often remain unaffected by the disease, can transmit to sons and more rarely, to daughters.

A few muscular dystrophies occur as a result of a new gene abnormality or mutation and are not inherited.

Risk Factors

Some X-linked types of muscular dystrophy affect only males, and are not a risk to women. Others affect both males and females.

Diagnosis

Muscular dystrophy may occur at any stage of a person's life. The type of the disease diagnosed is based in part on whether the muscular dystrophy appears during infancy, childhood, or middle years. It also depends on the severity of muscle weakness, which muscles are affected, the rate of symptom progression, and the way the disease arises.

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