All about muscular dystrophy

Muscular dystrophy refers to a group of disorders involving a progressive loss of muscle mass and consequent power loss.

The main forms of muscular dystrophy may affect up to 1 in every 5,000 males.

The most common type of muscular dystrophy is Duchenne. It usually affects young people, but it may hit certain variations in adulthood.

Muscular dystrophy is caused by genetic mutations that interfere with muscle protein production required to build and maintain healthy muscles.

The causes are genetic. A family history of muscular dystrophy may increase the risk of an individual being affected by it.

There is no treatment at the moment but certain physical and medical therapies will boost symptoms and delay progression.

Important facts about muscular dystrophy

Here are a few key points regarding muscle dystrophy. The main article contains more descriptions and supporting information.

  • Muscular dystrophy is a collection of muscle-wasting conditions
  • Duchenne muscular dystrophy is the most common type
  • A lack of a protein called dystrophin is the main cause of muscular dystrophy
  • Gene therapies are currently being trialed to combat the disease
  • There is currently no cure for muscular dystrophy

What is muscular dystrophy?

Muscular dystrophy is a group of over 30 conditions which lead to weakness and degeneration of the muscle. As the situation goes forward it becomes more difficult to move. In certain cases it can impair breathing and heart function , leading to complications that endanger life.

The symptoms may be mild, increasing gradually over a normal lifespan depending on the type and severity, there may be moderate disability or it may be fatal.

There is presently no way of preventing or reverse muscular dystrophy but different types of therapy and drug treatment can improve the quality of life of a person and delay symptom progression.

Symptoms

Muscular dystrophy causes the gradual weakening of skeletal muscle.
Muscular dystrophy causes the gradual weakening of skeletal muscle.

Those are the signs of Duchenne muscular dystrophy, the disease’s most prevalent type.

Becker ‘s muscular dystrophy symptoms are similar but appear to begin in the mid-twenties or later, are milder, and develop more gradually.

Early symptoms include:

  • a waddling gait
  • pain and stiffness in the muscles
  • difficulty with running and jumping
  • walking on toes
  • difficulty sitting up or standing
  • learning disabilities, such as developing speech later than usual
  • frequent falls

As time goes on, the following become more likely:

  • inability to walk
  • a shortening of muscles and tendons, further limiting movement
  • breathing problems can become so severe that assisted breathing is necessary
  • curvature of the spine can be caused if muscles are not strong enough to support its structure
  • the muscles of the heart can be weakened, leading to cardiac problems
  • difficulty swallowing, with a risk of aspiration pneumonia. A feeding tube is sometimes necessary.

Treatment

There is actually no treatment for muscular dystrophy. Medications and multiple treatments help delay disease development and keep the patient healthy for as long as possible.

Drugs

The two most commonly prescribed drugs for muscular dystrophy are:

  • Corticosteroids: This type of medication can help increase muscle strength and slow progression, but long-term use can weaken bones and increase weight gain.
  • Heart medications: If the condition impacts the heart, beta blockers and angiotensin-converting enzyme (ACE) inhibitors may help.

Physical therapy

  • General exercises: A range of motion and stretching exercises can help combat the inevitable inward movement of the limbs as muscles and tendons shorten. Limbs tend to become fixed in position, and these types of activities can help keep them mobile for longer. Standard low-impact aerobic exercises such as walking and swimming can also help slow the disease’s progression.
  • Breathing assistance: As the muscles used for breathing become weaker, it may be necessary to use devices to help improve oxygen delivery through the night. In the most severe cases, a patient may need to use a ventilator to breathe on their behalf.
  • Mobility aids: Canes, wheelchairs, and walkers can help the person stay mobile.
  • Braces: These keep muscles and tendons stretched and help slow their shortening. They also give added support to the user when moving.

Types

There are different types of muscular dystrophy, including the following:

  • Duchenne muscular dystrophy: The most common form of the illness. Symptoms normally start before a child’s third birthday; they are generally wheelchair-bound by 12 years and die of respiratory failure by their early-to-mid-twenties.
  • Becker muscular dystrophy: Similar symptoms to Duchenne but with a later onset and slower progression; death usually occurs in the mid-forties.
  • Myotonic (Steinert’s disease): The myotonic form is the most common adult-onset form. It is characterized by an inability to relax a muscle once it has contracted. The muscles of the face and neck are often affected first. Symptoms also include cataracts, sleepiness, and arrhythmia.
  • Congenital: This type can be obvious from birth or before the age of 2 years. It affects girls and boys. Some forms progress slowly whereas others can move swiftly and cause significant impairment.
  • Facioscapulohumeral (FSHD): Onset can be at almost any age but is most commonly seen during teenage years. The muscular weakness often begins in the face and shoulders. People with FSHD may sleep with their eyes slightly open and have trouble fully closing their eyelids. When an individual with FSHD raises their arms, their shoulder blades protrude like wings.
  • Limb-girdle: This variant begins in childhood or teenage years and first effects the shoulder and hip muscles. Individuals with the limb-girdle muscular dystrophy might have trouble raising the front part of the foot, making tripping a common problem.
  • Oculopharyngeal muscular dystrophy: Onset is between the ages of 40 and 70 years. Eyelids, throat, and face are first affected, followed by the shoulder and pelvis.

Causes

Muscular dystrophy is caused by X-chromosome mutations. Each type of muscular dystrophy is caused by a different set of mutations but all prevent dystrophin from being formed by the body. Dystrophin is an important protein for muscle formation and repair.

Duchenne muscular dystrophy is caused by certain gene mutations encoding the cytoskeletal protein dystrophin. Dystrophin provides only for 0.002 percent of the total proteins in the striated muscle, but it is an important molecule for general muscle function.

Dystrophin is part of an extraordinarily complex group of proteins helping the muscles to function properly. The protein helps to bind various components together within muscle cells and binds them all to the sarcolemma-the outer membrane.

This process does not function properly if dystrophin is missing or deformed, and disruptions occur in the outer membrane. This weakens the muscles and can seriously damage the muscle cells themselves as well.

Dystrophin is almost completely absent in Duchenne muscular dystrophy; the less dystrophin created, the worse the symptoms and etiology of the disease. A decrease in the volume or scale of the dystrophin protein occurs in Becker muscular dystrophy.

The most known gene in humans is the gene coding for dystrophin. For Duchenne and Becker muscular dystrophy more than 1,000 mutations were found in this gene.

Diagnosis

A variety of strategies for the definitive diagnosis of muscular dystrophy exist:

genetic mutations
The genetic mutations involved in muscular dystrophy are well known and can be used to make a diagnosis.
  • Enzyme assay: Damaged muscles generate creatine kinase (CK). Elevated levels of CK in the absence of other forms of muscle damage may indicate muscular dystrophy.
  • Genetic testing: Such changes may be screened for as genetic mutations are known to occur in muscle dystrophy.
  • Heart monitoring: Electrocardiography and echocardiograms can detect changes in the musculature of the heart. This is especially useful when diagnosing myotonic muscular dystrophy.
  • Lung monitoring: An additional evidence may be given by testing lung function.
  • Electromyography: A needle for measuring electrical activity is mounted within the muscle. The findings may be displaying symptoms of muscle disease.

Outlook

The viewpoint would depend on the type of muscular dystrophy and how serious the symptoms are.

Duchenne muscular dystrophy can cause life-threatening complications, such as trouble breathing and heart attacks.

Individuals with this disorder typically didn’t last into their 20s in the past, but improvement is enhancing outlook.

Actually the average life expectancy for people with Duchenne is 27 years, and as care progresses, it can increase over time.

A person suffering from muscular dystrophy may require lifelong assistance.

Current research

Everything has been understood about the muscular dystrophy causes, both muscular and genetic, and although a full cure may be some distance away, there are avenues of study that draw ever closer to one.

Gene replacement therapy

Gene therapy is just one strand of research into treating muscular dystrophy.
Gene therapy is just one strand of research into treating muscular dystrophy.

As the specific gene involved in muscular dystrophy has been found, it is a wise idea to find a replacement gene that might produce the missing dystrophin protein.

This strategy raises complex issues, including the immune system’s ability to repel a new protein, and the large size of the dystrophin gene that needs to be replaced. Viral vectors are also difficult to aim directly to the skeletal muscle.

Another strategy targets the development of utrophins. Utrophin is a dystrophin-like protein not affected by muscular dystrophy. If the production of utrophin could be upregulated, the illness could be stopped or slowed.

Altering protein production

When protein synthesis machinery reads the dystrophin gene when it hits a mutation it will stop and not complete the protein. Drugs are being trialed that cause the protein-making equipment to skip the mutated content and still continue to create dystrophin.

Drugs to delay muscle wasting

Instead of attacking the genes causing muscle dystrophy, some researchers are seeking to slow down inevitable muscle wasting.

Muscles, may fix themselves in normal circumstances. Research on managing or increasing such repairs may show some benefits for muscular dystrophy people.

Stem cell research

Scientists are exploring the possibility of inserting muscle stem cells that can produce the deficient dystrophin protein.

Recent studies are looking for the most effective type of cells to use and methods of supplying them to the skeletal muscle.

Myoblast transplantation

Myoblasts (also called satellite cells) repair and replace faulty muscle fibers during early stages of muscle dystrophy. The muscles are gradually transformed into connective tissue as the myoblasts are exhausted.

Several experiments have tried to inject modified myoblast cells into muscles to take over the normal depleted myoblasts.

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