Muscular dystrophy

Muscular dystrophy (MD) refers to a group of inherited genetic muscle conditions.

MD causes progressive muscle weakness and muscle wasting because of the degeneration (deterioration) of muscle cells. This means it gets worse over time. It often starts with a particular group of muscles before progressing to affect other muscles in the body.

Types of muscular dystrophy

According to Muscular Dystrophy UK, there are over 60 rare progressive muscle-weakening and wasting conditions affecting 110,000 children and adults in the UK.

Some of the different types of muscular dystrophy are identified by the groups of muscles that are affected first.

The most common types of MD are:

Causes of muscular dystrophy

Muscular dystrophy usually develops because a faulty gene has been inherited from one or both parents. It normally runs in families.

MD is caused by mutations (changes) in the genes responsible for healthy muscle structure and function. This leads to muscle weakness and can eventually result in disability.

A gene mutation is like a spelling mistake within the gene code. This can lead to a change in the protein expression in the muscle causing structural changes and damage in the muscle.

You have 2 copies of every gene (apart from the sex chromosomes). You get a copy from each parent. If one or both of your parents has the mutated gene that causes MD, it can be passed on to you.

Depending on the type of MD the condition could be a:

  • recessive inherited disorder
  • dominant inherited disorder
  • sex linked (X-linked) disorder

In rare cases, the genetic mutation can develop as a new event in the family (spontaneous mutation).

Recessive inherited MD

If you have recessive inherited MD, you’ve inherited an altered version of the gene that causes MD from both of your parents. This means both copies of your genes are altered.

If you inherit an altered version of the gene from only one parent, you’ll be a carrier of the condition. This means although you don’t have the condition, there’s a chance you might pass it on to any children you have, if the other parent is also a carrier. The risk of this is very small. If your partner is related to you, the risk is higher.

If both parents carry an altered version of the gene, there’s a:

  • 1 in 4 chance their child will have MD
  • 1 in 2 chance their child won’t have MD but will carry the mother’s or father’s faulty gene
  • 1 in 4 chance they’ll not have MD and they’ll not inherit any mutated genes
Dominant inherited MD

If you have a dominant inherited MD, you only need to inherit the altered gene from one parent to be affected.

This means, if you have a child with an unaffected partner there’s still a 1 in 2 chance your child will develop the condition.

The types of MD that are inherited in this way include:

  • myotonic dystrophy
  • facioscapulohumeral MD
  • oculopharyngeal MD
  • some types of limb-girdle MD
Sex linked (X-linked) MD

Males have one X and one Y chromosome (long threadlike structures of DNA). Females have two X chromosomes.

A sex linked disorder is caused by a mutation in a gene on the X chromosome.

As males only have one copy of each gene on the X chromosome, they’ll be affected if one of those genes is mutated.

Because females have 2 copies of the X chromosome, they’re less likely to develop an X-linked condition. This is because the healthy copy of the chromosome can usually compensate (mask) the mutated version. This means that although females can still be affected by X-linked disorders, the symptoms are likely to be less severe.

Types of MD inherited like this include:

  • Duchenne MD
  • Becker MD

These conditions are more severe and more common in males.

Spontaneous gene mutation

Sometimes, spontaneous gene mutations can cause MD. This happens when the gene mutates for no apparent reason, changing the way the cells operate.

If a person with MD has no family history of the condition, it might be caused by a spontaneous gene mutation.

Alternatively, if a child with no family history has MD, the condition may be recessive. There might be gene mutations on both sides of the family but they haven’t affected anyone until a child inherits a copy of the altered gene from both parents.

Read about genetic testing

Diagnosing muscular dystrophy

There are different methods used to diagnose MD like:

Investigating symptoms

Your GP will ask about your or your child’s symptoms. It’s helpful for them to understand when the symptoms first appeared and which muscles they affect.

You’ll be asked about your child’s development. For example, they’ll ask about what age they started to sit up, stand, crawl and walk.

You should tell your GP if you have any concerns about your child’s overall development.

Family history

You should tell your GP if there’s a history of MD in your family. This might help identify which type of MD you or your child might have.

It’s also helpful for your GP to know if anyone in your family has had similar symptoms or has undiagnosed muscle problems.

Blood tests

Your blood sample might be tested for creatine kinase. Creatine kinase is a protein usually found in muscle fibres.

When muscle fibres are damaged, creatine kinase is released into the blood. If you have muscle damage caused by some types of MD, you’ll likely have a higher level of creatine kinase in the blood compared to someone without MD.

Your blood sample might be used for genetic testing. This might help identify the cause of muscle problems.

Read more about blood tests

Muscle biopsy

You might have a small sample of muscle tissue removed to be viewed under a microscope and tested for different proteins. The sample might be taken through a small cut (incision), or by using a hollow needle, from your leg or arm depending on the type of MD you have.

The muscle biopsy is usually done under local anaesthetic. Children might have the procedure under general anaesthetic.

A muscle biopsy can help identify which gene is causing MD and therefore which type of MD you have.

Other tests

There are other tests available to help determine which type of MD you have.

Other tests might include:

Nerve conduction studies and electromyography (EMG)

These tests are used to examine the electrical activity in the nerves and muscles while at rest and in use.

Children may have this test under general anaesthetic.

MRI scan

An MRI scan uses strong magnetic fields to produce detailed images of inside your body. The MRI scan can help to identify the muscles affected and show the extent of the muscle damage.

Sometimes, an MRI scan can show a pattern of muscle involvement which can immediately determine which type of MD you have. This would mean a blood test could be used to confirm the diagnosis without the need for a muscle biopsy.

CT scan

A computerised tomography (CT) scan uses X-rays and a computer to create detailed images of inside your body. This can be used to look for any muscle damage.

Chest X-ray

A quick and painless X-ray might be used to create images of the inside of the body. This will look for any abnormal enlargement of your heart or any fluid around your lungs.

Electrocardiogram (ECG)

During an electrocardiogram (ECG), electrodes (flat metal discs) are attached to your arms, legs and chest to measure the electrical activity in your heart. This will look for an irregular heartbeat or any damage in the heart muscle.

Echocardiogram

An echocardiogram scan of your heart uses ultrasound waves to create a picture of your heart muscles and valves. An echocardiogram will check the heart function and structure.

Pulmonary function tests

These are breathing tests used to assess if your respiratory muscles have been affected by your condition.

Genetic testing

Once your healthcare professional identifies what type of MD you or your child might have, you may be offered genetic testing. Genetic testing can sometimes confirm a diagnosis of a particular type of MD.

Genetic testing might be used to identify if you’re a carrier of MD or to confirm a pre natal diagnosis (when a foetus is diagnosed with a condition before birth).

Speak to your GP if you or your child has symptoms of:

  • muscle weakness
  • mobility problems

Treatment of muscular dystrophy

Although there’s no cure for MD, there are treatments that can help to manage the symptoms.

There are many different types of MD and people experience varying symptoms. Your treatment will be tailored to your needs.

Mobility and breathing problems

You might gradually start to lose strength and mobility as your MD symptoms progress.

Physical problems might be helped with:

  • low-impact exercise like swimming
  • physiotherapy to work on muscle strength and flexibility
  • physical aids like a walking stick, crutches or a wheelchair
  • occupational therapy to help maintain independence

If your chest muscles become weak, you might need a machine to help with your breathing. This can be particularly helpful while sleeping.

There are cough assist machines which can help you cough up and remove secretions (phlegm). Using an Ambu bag can help to preserve your chest wall muscle strength.

Steroids

If you have Duchenne MD, corticosteroid medicine (steroids) can help improve your muscle strength and function. This can slow down the progress of muscle weakness.

Steroids are available in tablet or liquid form.

Read more about steroids and their possible side effects

Ataluren (Translarna)

Ataluren (Translarna) is used to treat some children with Duchenne MD that can still walk. It’s only effective for children with MD with a specific gene mutation.

Ataluren can help slow down the progress of muscle weakness. It’s prescribed as a sachet of granules which can be mixed into liquids or food like yoghurt and eaten.

Swallowing problems

Sometimes MD can cause swallowing difficulties (dysphagia), especially as the condition progresses. This can increase the risk of choking and chest infections if food or liquid gets into your lungs.

Changing the consistency of your food or learning exercises to improve your swallowing can help prevent choking and chest infections.

You might be offered surgery to treat swallowing problems. This might be a minor procedure where one of the muscles in your throat are stretched or cut in a procedure called cricopharyngeal myotomy. Or a small balloon might be inflated in your gullet (oesophagus) to expand and stretch the gullet and improve swallowing.

If you’re unable to get enough nutrition by swallowing, you might be offered a feeding tube (gastrostomy or PEG). This would be implanted into your stomach through your abdomen (tummy) during surgery.

Heart problems

Your heart muscles, and the muscles you use to breathe, might be affected by MD, depending on which type of MD you have. This can cause life threatening complications.

Your heart function will be closely monitored if you’re diagnosed with a type of MD which is likely to affect your heart.

You’ll have the following tests:

  • electrocardiograms (ECGs) to examine your heart rhythm
  • echocardiogram
  • MRI scan

You’ll see a cardiologist (heart specialist) for further tests and monitoring if the type of MD you have is likely to cause heart problems.

You might be advised to take medicine for your heart problems like ACE inhibitors or beta blockers.

If you have myotonic dystrophy or Emery-Dreifuss MD you might have a pacemaker fitted to help regulate your heartbeat. Alternatively, you might have a ICD (implantable cardioverter defibrillator) inserted.

Corrective surgery

In severe cases of MD, you might be offered surgery to help treat physical problems caused by the condition.

Some types of MD can cause scoliosis. Surgery might be used to correct and to prevent scoliosis from getting worse.

If you have droopy eyelids which are affecting your vision, surgery can help improve this.

Tight joints caused by tendon contractures can be loosened by surgically lengthening or releasing the tendons. This should improve movement.

Scapular fixation, where shoulder blades are surgically fixed to the back of the ribs, is occasionally used to treat weak shoulder muscles.

You’ll be referred to a specialist to discuss surgical options if you or your child are offered surgery. This will allow you to discuss the risks of any procedure you might have.

There is research ongoing for many types of MD. Visit Muscular Dystrophy UK to read about the latest research into treatments for MD.

Muscular Dystrophy UK also provide peer support, support groups, advocacy, practical information and signposting for people living with muscle wasting conditions.


Last updated:
12 April 2023