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The muscular dystrophies (MD) are a group of inherited genetic conditions that gradually cause the muscles to weaken, leading to an increasing level of disability.
MD is a progressive condition, which means it gets worse over time. It often begins by affecting a particular group of muscles, before affecting the muscles more widely.
Some types of MD eventually affect the heart or the muscles used for breathing, at which point the condition becomes life-threatening.
There's no cure for MD, but treatment can help to manage many of the symptoms.
MD is caused by changes (mutations) in the genes responsible for the structure and functioning of a person's muscles.
The mutations cause changes in the muscle fibres that interfere with the muscles' ability to function. Over time, this causes increasing disability.
The mutations are often inherited from a person's parents. If you have a family history of MD, your GP may refer you for genetic testing and counselling to evaluate your risk of developing the condition or having a child with MD, and to discuss the options available to you.
There are many different types of MD, each with somewhat different symptoms. Not all types cause severe disability and many don't affect life expectancy.
Some of the more common types of MD include:
In the UK, more than 70,000 people have MD or a related condition.
Duchenne MD is the most common type of MD. In the UK, about 100 boys are born with Duchenne MD each year, and there are about 2,500 boys living with the condition in the UK at any one time.
Myotonic MD is the second most common type of MD, affecting around one person in every 8,000.
Facioscapulohumeral MD is thought to affect around one in every 20,000 people in the UK, making it the third most common MD.
Many different methods can be used to diagnose the various types of MD. The age at which the condition is diagnosed will vary, depending on when symptoms first start to appear.
Diagnosis will involve some or all of the following stages:
Visit your GP if you or your child has any symptoms of MD. If necessary, your GP may refer you to a hospital for further tests.
There's no cure for MD, but a range of treatments can help with the physical disabilities and problems that may develop. These can include:
New research is looking into ways of repairing the genetic mutations and damaged muscles associated with MD. There are currently promising clinical trials for Duchenne MD.
Read more about treating MD.
If you have MD, your clinical team will pass information about you on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).
This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.
There are many different types of muscular dystrophy (MD). All types cause muscle weakness, but the areas affected and the severity of the symptoms are different.
Typical symptoms of some of the most common types of MD are explained below. Muscular Dystrophy UK also provides a dropdown list of specific muscle-weakening conditions.
As a result of the way it's inherited (see causes of MD), Duchenne MD mostly affects boys. Girls can occasionally be affected, although the condition tends to be milder in females.
Children with Duchenne MD usually start to have noticeable symptoms between one and three years of age. The muscles around their pelvis and thighs tend to be affected first and often appear bulkier than normal.
A child with Duchenne MD may:
Children with Duchenne MD may need a wheelchair by the time they're 8-14 years old, as their muscles weaken and they lose the ability to walk. They can also develop scoliosis, where the spine begins to curve sideways. This can lead to one shoulder or hip being higher than the other.
By their mid-teens, some people with Duchenne MD will develop dilated cardiomyopathy. This condition affects the heart muscles, causing the heart's chambers to enlarge and the walls to get thinner.
By their late-teens or early 20s, people with Duchenne MD may start to have breathing problems. The condition can also affect the intercostal muscles (muscle tissue between the ribs) and the diaphragm (the large, thin sheet of muscle between the chest and abdomen).
Once the heart and respiratory muscles are damaged, Duchenne MD becomes life-threatening. With medical care, most people with Duchenne MD die from heart or respiratory failure before or during their 30s.
As with other types of muscular dystrophy, myotonic dystrophy involves progressive muscle weakness and muscle wasting. However, it's often the smaller muscles that are affected first, such as those in the face, jaw and neck.
Myotonic dystrophy can appear at any time between birth and old age. It affects the same number of men and women.
As well as muscle weakness and wasting, symptoms can include:
Myotonic dystrophy is highly variable and often gets worse very slowly, with little change over long periods of time. However, it can become more severe as it's passed down through the generations.
Some people with myotonic dystrophy may never have a significant disability, although their heart rate will need to be monitored for abnormalities. This is because there's a risk of the electrical impulses that control the heartbeat travelling too slowly through the heart. In some people, the condition can also cause cataracts to develop at a younger age than usual.
Life expectancy for people with myotonic dystrophy can vary considerably. Many people have a normal life expectancy, but people with the more severe congenital form (present from birth) may die while still a newborn baby, or only survive for a few years.
Some people who first develop symptoms as a child or teenager may also have a shortened life expectancy. Most deaths related to myotonic dystrophy are related to pneumonia, breathing problems or heart problems.
If you have myotonic dystrophy, it's important that you're well informed about your condition, and that you tell any healthcare professionals you see that you have it. Myotonic dystrophy can cause difficulties with general anaesthetics and childbirth.
Facioscapulohumeral MD can affect both men and women. It tends to affect men slightly more than women, although the reason for this is unclear. Men also tend to be affected earlier and more severely.
About one in three people with facioscapulohumeral MD are unaware of any symptoms until well into adulthood. Others develop problems in early childhood. The condition tends to progress slowly.
Signs in your child may include:
Teenagers or adults may have shoulder aches, rounded shoulders or thin upper arms. As the condition progresses, it usually affects the muscles in the:
Around half of all people with facioscapulohumeral MD develop weakness in their leg muscles, and one or two in every 10 people with the condition will eventually need a wheelchair.
Facioscapulohumeral MD can develop unevenly, so the muscles on one side of the body may be affected more than the other. As the condition progresses slowly, it doesn't usually shorten life expectancy.
Like Duchenne MD, Becker MD mostly affects boys. Becker MD also affects similar areas of the body to Duchenne MD, although the symptoms tend to be less severe.
Symptoms of Becker MD usually begin in childhood, but they're often relatively mild at this point. For example, a child with the condition may:
During late childhood or early adulthood, people with Becker MD often find they have difficulty running, walking quickly and climbing stairs. As they get older, they may also find lifting objects above waist height difficult.
A person with Becker MD will often eventually need a wheelchair by the time they're 40-50 years old, although this is highly variable. For example, one person with Becker MD may be unable to walk by the time they're 16, while another person with the condition may be able to walk until they're 80.
If you have Becker MD, you're also at risk of developing dilated cardiomyopathy and breathing problems. However, Becker MD progresses at a slower rate than Duchenne MD, and those with the condition often have a normal lifespan.
Limb-girdle MD refers to a number of related conditions that cause weakness in the big muscle groups at the base of the arms and legs (around the shoulders and hips).
The first symptoms are often mobility problems affecting the hip girdle. It then progresses to the shoulder girdle ("girdle" means the bones around the shoulder or hip).
Symptoms of limb-girdle MD usually begin in late childhood or early adulthood, although the condition can affect people younger or older than this, depending on the specific type. Males and females are equally affected.
If you have limb-girdle MD, you may experience:
The muscle weakness will create problems such as difficulty lifting objects, running or getting out of a low seat.
How quickly limb-girdle MD progresses depends on the specific type. Many types get worse slowly, whereas others can develop more rapidly.
In oculopharyngeal MD, symptoms aren't usually apparent until a person is around 50 or 60 years old. It affects the muscles in the eyes (ocular) and the throat (pharyngeal).
Symptoms of oculopharyngeal MD can include:
As the eyelids droop, they can cover the eyes and impair vision. It's also possible to develop double vision.
Dysphagia can eventually make it difficult to swallow solid foods, liquids and even small amounts of saliva. This can lead to chest infections if food and drink is accidentally swallowed the "wrong way" into the lungs. However, with treatment to manage the symptoms, a person's life expectancy isn't usually altered.
People with Emery-Dreifuss MD often begin to develop symptoms during childhood or adolescence.
In the early stages, people with the condition usually develop muscle contractures (where the muscles and tendons become shortened and tightened, limiting the range of movement at nearby joints).
Areas commonly affected by muscle contractures include the arms, neck and feet. This means that people with Emery-Dreifuss MD may have difficulty straightening their elbows or bending their neck forward, for example.
Like all types of MD, Emery-Dreifuss MD also causes progressive muscle weakness, usually beginning in the shoulders, upper arms and lower legs. This can make it difficult to lift heavy objects or raise your arms above your head, and you may have an increased tendency to trip over things.
Later on, the hip and thigh muscles become weaker, making activities such as walking up stairs difficult. People with Emery-Dreifuss MD will often eventually require a wheelchair, as they become unable to walk.
Emery-Dreifuss MD can also affect the heart's electrical signals, causing heart block. This can result in people with the condition developing an abnormally slow heartbeat and palpitations, which can lead to episodes of lightheadedness or fainting. The slow heartbeat can often be treated successfully with an implanted pacemaker.
Due to the risk of serious heart and respiratory problems, someone with Emery-Dreifuss MD will often have a shortened life expectancy. However, most people with the condition live until at least middle age.
In most cases, muscular dystrophy (MD) runs in families. It usually develops after inheriting a faulty gene from one or both parents.
MD is caused by mutations (alterations) in the genes responsible for healthy muscle structure and function. The mutations mean that the cells that should maintain your muscles can no longer fulfil this role, leading to muscle weakness and progressive disability.
You have two copies of every gene (with the exception of the sex chromosomes). You inherit one copy from one parent, and the other copy from the other parent. If one or both of your parents has a mutated gene that causes MD, it can be passed on to you.
Depending on the specific type of MD, the condition can be a:
In a few cases, the genetic mutation that causes MD can also develop as a new event in the family. This is known as a spontaneous mutation.
These are explained in more detail below.
If you have a recessive inherited disorder, it means you've inherited an altered version of the gene that causes the condition from both of your parents (both your copies of the gene are altered).
If a child only inherits an altered version of the gene from one parent, they'll become a carrier of the condition. This means they're not affected, but there's a chance that any children they have will be if their partner is also a carrier.
If both parents carry an altered version of the gene that causes the condition, there's a:
Some types of limb-girdle MD are inherited in this way.
A dominant inherited disorder means you only need to inherit the mutated gene from one parent to be affected.
This means that if you have a child with an unaffected partner, there's still a 50% chance of your child developing the condition.
Types of MD inherited in this way include myotonic dystrophy, facioscapulohumeral MD, oculopharyngeal MD and some types of limb-girdle MD.
Chromosomes are long, threadlike structures of DNA. A male has one X and one Y sex chromosome, and a female has 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.
As females have two copies of the X chromosome, they're less likely to develop an X-linked condition, because the normal copy of the chromosome can usually cover for (mask) the altered version.
Females can still be affected by X-linked disorders, but the condition is usually less severe than when the gene alteration is present in an affected male.
Types of MD inherited in this way include Duchenne MD and Becker MD, which is why these conditions are more common and more severe in males.
Spontaneous gene mutations can occasionally cause MD. This is where the genes mutate for no apparent reason, changing the way the cells function. Spontaneous gene mutations can cause MD to develop in people who don't have a family history of the condition.
Another way a child with no family history can be affected is when the condition is recessive. The gene mutations may have been present on both sides of the family for many generations, but may not have affected anyone until a child inherited a copy of the altered gene from both parents.
Many different methods can be used to diagnose the various types of muscular dystrophy (MD).
The age at which MD is diagnosed will vary, depending on when the symptoms first start to appear.
Diagnosis will involve some or all of the following stages:
In the first instance, visit your GP if you or your child has any symptoms of MD. If necessary, your GP may refer you to a hospital for further tests.
Your GP will need to know about any symptoms of MD that you or your child have noticed and when they began to appear. For example, you or your child may be:
Identifying when symptoms first appeared and determining which muscles are affected is particularly useful in helping to diagnose different types of MD.
Duchenne MD is the most common type of MD in boys. Symptoms can be present from birth, but this is unusual and signs usually appear between 12 months and three years of age. You may notice that your child has difficulty walking or climbing stairs, or that they fall down more frequently than other children.
Your child may also find it difficult to stand up from sitting on the floor. They may use what's known as the Gower's manoeuvre to do this. This is where a child stands up by:
Visit your GP if you suspect your child may have MD. Your GP will look at the following when they examine your child:
If there's a history of MD in your family, it's important to discuss it with your GP. This can help to determine which type of MD you or your child might have.
For example, discussing the family history of limb-girdle MD will help your GP determine whether your type of MD is inherited as a recessive or a dominant condition (see causes of MD for more information).
A sample of blood may be taken from a vein in your or your child's arm to test it for creatine kinase (a protein usually found in muscle fibres).
When muscle fibres are damaged, creatine kinase is released into the blood. The muscle damage caused by some types of MD means that the level of creatine kinase in the blood will often be higher than normal.
A blood sample may also be used for genetic testing, and this can sometimes identify the cause of muscle problems without the need for a muscle biopsy.
A muscle biopsy involves removing a small sample of muscle tissue through a small cut (incision), or using a hollow needle, so it can be examined under a microscope and tested for proteins. The sample will usually be taken from the leg or arm, depending on the type of MD.
Analysing the protein in the muscle can help to determine which gene is causing MD and therefore which type of MD you have. For example, people with Duchenne MD and Becker MD have too little of the protein dystrophin in their muscles and it's usually an altered size.
Examining the muscle tissue under a microscope can also help to diagnose limb-girdle MD. Healthy muscle consists of closely packed, evenly sized fibres. In people with limb-girdle MD, these fibres may be missing, may be different sizes, or may have been replaced with fat.
A number of other tests can be used to find out more about the spread and extent of any muscle damage. This will help your doctor to identify or confirm which type of MD you have. Treatment can then be directed where it's most needed. Some tests are explained below.
Once the doctor – usually a geneticist or neurologist – has an idea about what type of MD may be affecting you or your child, they may arrange genetic testing to look into this.
Genetic testing is simpler for some types of muscle conditions, so it may be arranged at an early stage if a specific condition is suspected, or after many other tests if it's more difficult to diagnose.
There are many different genes that could potentially be responsible for MD, so it would be expensive and time-consuming to test them all. However, genetic testing can sometimes confirm a diagnosis.
For example, if you're diagnosed with Duchenne MD, tests can be carried out to check for a mutation in the dystrophin gene, because mutations in this gene are directly responsible for the condition.
Genetic testing can also be used to identify carriers of MD and to perform prenatal diagnosis (when a foetus is diagnosed before the baby is born).
There's currently no cure for muscular dystrophy (MD), but a variety of treatments can help to manage the condition.
As different types of MD can cause quite specific problems, the treatment you receive will be tailored to your needs. As your symptoms develop, the healthcare professionals treating you will advise on the options.
New research is investigating possible future treatments. Improved genetic testing can help if you're concerned about passing MD on to your children.
As MD progresses, it weakens your muscles and you gradually begin to lose mobility and strength. These physical problems can be helped with the following:
Once the chest muscles become too weak to control breathing properly, you may need machines to assist with your breathing and coughing, particularly while sleeping.
In people with Duchenne MD, corticosteroid medication (steroids) has been shown to improve muscle strength and function for six months to two years, and slow down the process of muscle weakening.
Steroid medication for Duchenne MD is available in tablet or liquid form, and current research suggests a daily dose is most effective. However, long-term use of steroids is associated with significant side effects such as weight gain and excessive hair growth.
Recent research has also shown that a creatine supplement can improve muscle strength in some people with MD, while causing few side effects.
Creatine is a substance normally found in the body that helps supply energy to muscle and nerve cells. It's often available as a supplement from pharmacies and health food stores.
If you have MD and decide to take creatine supplements, make sure you mention this to your doctors (GP and specialist).
People with some types of MD find swallowing increasingly difficult as the condition progresses. This is known as dysphagia and it can increase your risk of choking or developing a chest infection, if food and liquid get into the lungs.
Depending on the severity of your swallowing problems, there are a number of treatments that can be used. For example, a dietitian may help you alter the consistency of your food and you may be taught some exercises by a speech and language therapist, to improve your swallowing.
If necessary, surgery can also be used to treat swallowing problems. This may involve a minor procedure to cut one of the muscles in your throat, or a small balloon may be inflated in your gullet (oesophagus) to expand it.
If MD progresses to a point where you're unable to get enough nutrition by swallowing, a feeding tube (gastrostomy or PEG) may need to be surgically implanted into your stomach through your abdomen (tummy).
Some types of MD can affect the heart muscles and the muscles used for breathing. When the condition has progressed to this stage, it can become life-threatening.
It's important that your heart function is assessed regularly once MD has been diagnosed. For Duchenne and Becker MD, an electrocardiogram (ECG) examination of heart rhythm will be carried out at regular intervals, and you may also have an echocardiogram from time to time. A magnetic resonance imaging (MRI) scan may also be used to check for heart problems.
If any damage to your heart is detected, you may be referred to a cardiologist (heart specialist) for further tests and possibly more frequent monitoring.
You may be prescribed medication to treat your heart problems, such as ACE inhibitors to relax your arteries and make it easier for your heart to pump blood around your body, or beta-blockers to control irregular heartbeats (arrhythmias or dysrhythmias).
In some cases of myotonic or Emery-Dreifuss MD, a pacemaker may be fitted to correct an irregular heartbeat. A pacemaker is a small, battery operated device that can be implanted into your chest to regulate your heartbeat.
In some severe cases of MD, surgery may be necessary to correct physical problems that can occur as a result of the condition.
For example, if your child has Duchenne MD, there's a chance they'll develop scoliosis. Surgery can correct the scoliosis or prevent it getting worse, although there haven't been any trials to evaluate its effectiveness.
Other kinds of surgery may be used to treat specific symptoms:
If you or your child may benefit from having surgery, you'll be referred to a specialist to discuss the procedure and the risks involved.
New ideas for MD treatments are currently being developed.
Speak to your GP or specialist if you're interested in taking part in a clinical trial (a form of research that tests one treatment against another). You can also browse the database of clinical trials for MD.
Your GP or the healthcare professional treating you may know of any recent developments in healthcare that may benefit you.
Some examples of current research ideas are explained below.
Trials are now in progress in the UK and Netherlands to see if "exon skipping" may be a useful way of treating Duchenne MD. Exons are sections of DNA that contain information for proteins.
In Duchenne and Becker MD, some of the exons are missing or duplicated, which can interfere with the dystrophin protein being produced.
Researchers are currently investigating ways of "skipping" additional exons in the dystrophin gene. This could mean that more dystrophin would be produced, reducing the severity of MD symptoms.
Current trials are focused on treatment that would apply to Duchenne MD, but it may become applicable to Becker MD in the future.
Stem cells are cells that are at an early stage of development. This means they have the ability to turn into any type of cell in the body.
Some research is currently focusing on whether stem cells can be turned into muscle cells and used to regenerate damaged muscle tissue.
Genetic testing may be useful for prospective parents who have a family history of muscular dystrophy (MD) and are worried about passing the condition on to their children.
Speak to your GP, who can refer you for genetic screening and counselling.
Genetic testing can be used to:
Genetic testing is likely to be used more often in the future, because knowing the precise cause of MD may determine what type of treatment will be most effective.
Some types of MD can be carried without causing clear signs of the condition. This applies to recessive inherited disorders, sex-linked conditions and even some dominant conditions. Genetic testing can determine who's carrying the disorder.
For example, a woman with a family history of Duchenne MD, but no symptoms herself, may be carrying the gene that causes it. DNA can be taken from cells in her blood, saliva or tissue and compared with a sample from a family member who has the condition, to find out if she's carrying the faulty gene.
If you or your partner are a carrier of MD and are at risk of passing the condition on to your child, your genetic counsellor will discuss your options with you.
Read more about the causes of MD for more information about how MD is inherited.
Genetic testing can also be used for prenatal diagnosis. This is when a baby is diagnosed with MD before birth using tests carried out during pregnancy. You may be offered these tests if you're pregnant and there's a possibility that your unborn baby has MD.
There are two main ways of performing a prenatal diagnosis. One is chorionic villus sampling (CVS), which involves removing tissue from the placenta for analysis, usually after 11 weeks into the pregnancy.
The other method is amniocentesis, which isn't usually carried out until 15-16 weeks of pregnancy. A needle is inserted into your abdomen (tummy) so that a sample of the amniotic fluid that surrounds the foetus in the womb can be taken. Amniotic fluid contains cells that have been shed by the foetus.
Both CVS and amniocentesis carry a small risk of causing a miscarriage.
The cells from the foetus can be tested to determine whether they have the genetic mutation responsible for MD. If they do, the baby is likely to develop MD at some stage after birth.
If this is the case, your genetic counsellor can discuss your options with you, which will often include terminating the pregnancy. Such decisions can be very difficult and personal.
Be aware that there are limitations to this kind of diagnosis. Tests can give misleading or unexpected results. It's important to discuss prenatal testing and what the possible results mean before going ahead with the procedure. Expert genetic counselling can be very helpful in these circumstances to help people make the decision that's right for them.
A normal test result doesn't guarantee that the baby will be healthy. The test only looks for the particular type of MD in the family, but not for all other possible problems. A prenatal diagnosis can only be carried out if there's a precise genetic diagnosis of the family's condition.
Newer tests are being developed that can be performed by taking a sample of blood from the mother and testing the free foetal DNA (ffDNA). This is known as non-invasive prenatal diagnosis (NIPD).
NIPD is currently used to determine the sex of a foetus when it's medically important to know this, as well as the foetus' Rhesus blood group. It's hoped that NIPD will soon be able to diagnose conditions such as Duchenne MD.
For couples at risk of having a child affected by MD, another possible option is to use in vitro fertilisation (IVF) and then test early embryos for the condition. It allows only unaffected embryos to be transferred into the woman. This is known as pre-implantation genetic diagnosis (PGD).
While PGD has the advantage of avoiding the termination of foetuses affected by the condition, it also has a number of drawbacks. These include the modest success rate of becoming pregnant after IVF, as well as the substantial social, financial and emotional burdens of the combined IVF and PGD process. Apart from couples who need IVF so they can conceive a child, the number of people who use PGD is small.