What Is Muscular Dystrophy?

Larissa Banitt, RN
·8 min read
Yasser Chalid / Getty Images
Yasser Chalid / Getty Images

Medically reviewed by Nicholas R. Metrus, MD

Muscular dystrophy (MD) is a genetic disorder that causes muscle weakness that gets worse over time. There are more than 30 types of this disease that differ in many ways, including which muscles are affected, the age symptoms begin, and how fast it progresses. About 250,000 people in the United States have some form of muscular dystrophy, with Duchenne MD and Becker MD being the most common.

There is currently no known way to cure or prevent muscular dystrophy in someone who has the genetic mutations that cause it, but treatments exist that can help slow and manage the symptoms.

Types

Muscular dystrophy is a group of over 30 conditions that cause muscle weakness that gets worse over time. They can be categorized by:

  • The different genetic mutations that cause them

  • The age at which the condition appears

  • Which muscles are affected

  • How severe the weakness becomes

  • How quickly the weakness progresses

The nine major types of MD include:

  • Duchenne muscular dystrophy: This is the most common type of MD, making up around 50% of cases. The disease largely affects people assigned male at birth and begins showing signs in the toddler years.

  • Becker muscular dystrophy: This type is closely related to but often less severe than Duchenne MD. The condition appears between the ages of 11-25.

  • Facioscapulohumeral muscular dystrophy (FSHD): This type, also known as Landouzy-Dejerine disease, is the third most common type of muscular dystrophy. The disease affects muscles in the face, shoulders, and upper arms first.

  • Congenital muscular dystrophy: This condition refers to a cluster of muscular dystrophies that are either present at birth or appear before two years of age. It affects all genders equally.

  • Distal muscular dystrophy: This describes a set of at least six conditions that affect "distal" muscles. Distal means "farther away," in this case from the trunk of the body, meaning the condition affects your forearms, lower legs, hands, and feet the most.

  • Emery-Dreifuss muscular dystrophy: This type primarily affects children who are assigned male at birth, but children who are assigned female at birth who carry the gene may experience heart complications without muscle weakness.

  • Limb-girdle muscular dystrophy (LGMD): LGMD refers to a group of conditions that result in loss of muscle mass in voluntary muscles, particularly around the shoulders and hips.

  • Myotonic dystrophy (DM1): This type of MD includes myotonia, which is when the ability to relax muscles is impaired.

  • Oculopharyngeal muscular dystrophy: This type of MD usually begins in someone's 40s and 50s. It primarily affects eye and throat muscles, but also causes weakness throughout the body.

Muscular Dystrophy Symptoms

The hallmark symptom of muscular dystrophy is muscle weakness that gets worse over time. Which muscles are most likely to be affected often depends on the type of muscular dystrophy someone has. Symptoms may change or intensify as the disease progresses.

For example, with Duchenne MD, early symptoms often include difficulty climbing stairs, frequent falls, and a "waddling" gait. These symptoms will progress until you may no longer be able to walk on your own. Some people also need breathing assistance from a ventilator due to muscle weakness that hurts their ability to breathe independently.

Some other symptoms someone with MD may have include:

  • Walking on one's toes

  • Hearing loss

  • Difficulty swallowing (dysphagia)

  • Mental impairment

  • Weight loss

What Causes Muscular Dystrophy?

The majority of types of muscular dystrophy are caused by mutations in your genes (segments of your DNA) that affect muscle proteins. Most of the time you inherit these mutations from your parents, but occasionally they may occur on their own. These spontaneous mutations may then be passed down to your children.

There are several common ways that these mutated genes are inherited: autosomal dominant inheritance, autosomal recessive inheritance, and X-linked recessive inheritance.

With autosomal dominant inheritance, only one parent needs to have the mutated gene for their child to inherit it. If one of the parents has a copy of the mutated gene, their children have a 50% chance of inheriting the condition, but if a parent has two copies of the gene there is a 100% chance the child will inherit it.

With autosomal recessive inheritance, both parents need to have the mutated gene in order for their child to inherit the condition. If each parent has one copy of the gene, there is a 25% chance it will get passed down to their child.

X-linked recessive genes are genes carried on the X chromosome. Females usually have two X chromosomes whereas male individuals generally have an X and Y chromosome. Genetic conditions that affect the X chromosome affect more males than females. This is because females need both X chromosomes to contain the mutated gene to have the disease, but males only need their one X chromosome to be affected before they show signs of the disease.

Diagnosis

When diagnosing muscular dystrophy, your healthcare provider will begin by asking you about your medical history and your symptoms. Then, they will likely run some tests both to confirm the diagnosis of MD and rule out any conditions that it might be instead. Some of these tests include:

  • Blood tests: You will get blood drawn and they will test it for substances that may signal muscle weakness.

  • Muscle biopsies: Your provider may take a small sample of muscle tissue (called a biopsy) and test it for signs of MD.

  • Genetic testing: A geneticist (a professional specializing in genes and genetic conditions) will take a sample, usually of blood or spit, to see if you have the genes associated with MD.

Some other tests might include tests to rule out other disorders affecting the nervous system, heart tests, exercise tests, and imaging.

Treatments for Muscular Dystrophy

There is currently no cure for MD. The treatments available focus on slowing the progression of and reducing the severity of the symptoms. Some main treatments someone with MD may use are:

  • Physical therapy can promote muscle function by keeping them flexible and strong

  • Respiratory therapy can help prevent or delay breathing problems in people with MD. They can also provide education and assistance if someone with MD needs to use a ventilator to breathe

  • Speech therapy may be helpful for people who have muscle weakness in their face and throat. It can teach them how to maximize their ability to speak.

  • Occupational therapy can help people with MD learn new ways to complete daily tasks, such as eating and getting dressed, as their abilities change.

  • Surgery may be utilized by some people with MD to treat symptoms. Treating scoliosis, having cataracts removed, or having a pacemaker placed may be all necessary treatments for complications of their disease.

  • Medications such as glucocorticoids have been found to slow the progression of weakness in some people with MD. Other medications may be used to treat muscle spasms or high blood pressure that are associated with MD.

  • Gene-based therapy is a newer area of treatment with many ongoing studies trying to determine how to slow the progression of MD. However, there are a few therapies available via intravenous injection that treat MD.

Prevention

There is currently no way to prevent MD or stop its progression. However, new research is being performed all the time.

Complications

MD can cause a variety of complications, especially as the disease progresses. Certain complications are more common with certain types of MD. Some complications associated with MD are:

  • Cardiomyopathy: A disease of the heart muscle that prevents it from effectively pumping blood

  • Lordosis: A condition that causes an excessive inward curve of the spine

  • Scoliosis: A sideways curve in the spine

  • Contractures: Shortening of muscles and tendons around joints, which limits mobility in the area

  • Respiratory infections: Result from people with MD having difficulty breathing and swallowing, resulting in food, drink, and saliva being inhaled and starting an infection

Living with Muscular Dystrophy

Living with MD will look very different from person to person depending on what type of MD they have. Life expectancy and quality of life can vary drastically. People with MD will need to adapt as their disease progresses, but what that looks like and what support they need is highly individual. Although there is no cure at this time, research is being done every day to better understand this condition and develop new medications and tools to support people with it.

Frequently Asked Questions

Can muscular dystrophy be cured?

No, there is currently no cure for muscular dystrophy (MD), but research is actively being conducted.

How fast does muscular dystrophy progress?

MD progresses at different rates depending on which type you have. Certain therapies and treatments may also delay the disease's progression.

What can trigger muscular dystrophy?

Some people who are not born with the genetic mutation for muscular dystrophy can acquire it later in life. These "spontaneous mutations" can occur through several means, including spontaneous DNA damage and errors in the DNA replication process.

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