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Muscular Dystrophy - A Guide

Muscular dystrophy (MD) is a genetic (inherited) condition that over time gradually
causes the muscles to weaken. This leads to an increasing level of disability.

Introduction
Symptoms
Causes
Diagnosing
Treating
Preventing
More Information

Introduction

There are several different types of MD, with different symptoms and patterns of progression. Not all types of MD cause severe disability, but there is currently no cure for the condition.

MD is caused by mutations (cellular changes) in the genes that are responsible for the structure and functioning of a person’s muscles. The mutations can occur spontaneously, but they are normally inherited from a person’s parents.

The mutations cause changes in the muscle fibres, which interferes with the muscle’s ability to function. Over time, this causes increasing disability.

Types of muscular dystrophy

There are over 30 types of MD, each with slightly different symptoms. They can appear at different ages, affect different muscles, and progress at different rates. Some of the more common types of MD are listed below.

Duchenne muscular dystrophy

Duchenne MD is the most common and most severe form of MD. It usually affects boys and is diagnosed at around three years of age. It starts in the leg muscles before quickly progressing to other muscles groups.

Becker muscular dystrophy

Becker MD is closely related to Duchenne MD, but it is milder and less common. Like Duchenne MD, Becker MD tends to affect boys, although it is not usually diagnosed until around 10 years of age. It also progresses slower.

Myotonic muscular dystrophy

Myotonic MD is the most common form of MD in adults, although it can appear at any age. Both sexes can develop myotonic MD, which affects the smaller muscles, such as those in the face, jaw, neck, and hands.

Limb-girdle muscular dystrophy

Limb-girdle MD has around 15 different varieties. It can affect both sexes and usually appears in early adulthood. Limb-girdle MD initially starts in the muscles around the hip girdle and the shoulder girdle, but it can also progress quite quickly to other areas.

Facioscapulohumeral muscular dystrophy

Facioscapulohumeral MD affects the muscles in the face (facio), shoulders (scapula), and upper arm (humeral). This can affect both sexes, with symptoms starting between 10-40 years of age and progressing slowly.

Oculopharyngeal muscular dystrophy

Oculopharyngeal MD affects the muscles of the eye (ocular) and throat (pharyngeal). The condition affects both sexes, usually from between 50-60 years of age.

How common is muscular dystrophy?

Duchenne MD is the most common type of MD. Worldwide, it affects one boy who is born in every 3,500 . The second most common type is myotonic MD, which affects around one person in every 8,000 worldwide.

Other types of MD are less common - for example, facioscapulohumeral MD affects approximately one person in every 20,000 in Britain. As most cases are inherited, whether or not someone is likely to have MD will depend on whether any of their close relatives have ever had the condition.

Outlook

MD is a progressive condition, which means that it gets worse rather than better. It can start with one group of muscles and then move onto others. If MD begins to affect the cardiac (heart) muscles, or the respiratory system (breathing) muscles, it then becomes life-threatening.

The progression of MD varies, not only between the different types, but within them as well. Some genetic mutations can cause a milder version of the condition, and some will be more severe.

Children with Duchenne MD may be in a wheelchair by the age of 10, and the condition can be life-threatening by the age of 30. Those with Becker MD may need a wheelchair by the time that they are 40 or 50 years of age, but they should be able to live a normal lifespan.

Treatment can help with the physical disabilities and cardiac problems, but cannot cure the condition. New research is looking into ways of repairing the genetic mutations and damaged muscles, but it is still in the early stages.

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Symptoms of muscular dystrophy

The symptoms of muscular dystrophy (MD) and their severity will vary from person to person. They will depend on:

  • the type of MD that you have, and
  • when your symptoms first appeared.

Some of the more common symptoms for some types of MD are explained below. See the useful links section for more information about these and other types of MD.

Duchenne muscular dystrophy

Your child will first start to show signs of Duchenne MD between 1-3 years of age. The muscles around the pelvis and thighs tend to be affected first. They often appear bulkier than normal even though there is progressive weakening. Your child may:

  • have difficulty walking,
  • have difficulty standing up,
  • be unable to climb the stairs without support, and
  • have learning, or behavioural, difficulties.

Children with Duchenne MD may need a wheelchair by 10 years of age. They can also develop scoliosis, which is where their spine begins to curve sideways. This can lead to one shoulder, or one hip, being higher than the other.

By the mid-teens, some people with Duchenne MD will develop dilated cardiomyopathy. This is where the condition affects your heart muscles, causing the chambers of the heart to become enlarged and the heart walls to become thinner.

By late teens, or early twenties, Duchenne MD can begin to cause respiratory (breathing) problems. The condition can affect your intercostal muscles (the muscle tissue between your ribs) and your diaphragm (the main muscle between the chest and the abdomen that you use during breathing).

Once the heart and respiratory muscles are damaged, Duchenne MD becomes life-threatening. In most cases, someone with Duchenne MD will die from cardiac or respiratory failure before they are 30 years of age.

Becker muscular dystrophy

The symptoms of Becker MD are similar to those of Duchenne muscular dystrophy. However, they are milder and do not usually appear until a person is 10 or 11 years of age, or older. If your child has Becker MD, they may:

  • be late learning to walk,
  • havemuscle cramps when exercising (a painful spasm in the muscle), and
  • struggle with sport at school.

In their teenage years, and throughout their twenties, people with Becker MD may have difficulty running, walking quickly, and climbing stairs. As they get older, they may find it difficult to lift objects above waist height and, by around 40 or 50 years of age, they may need to use a wheelchair.

If you have Becker MD, you are also at risk of developing dilated cardiomyopathy and respiratory problems. However, Becker MD progresses at a slower rate than Duchenne MD, and those with the condition usually live a normal lifespan.

Myotonic muscular dystrophy

As with other types of muscular dystrophy, myotonic MD involves progressive muscle weakness and wasting. However, it is the smaller muscles, such as those in your face, jaw, neck, and hands that are affected, rather than the larger muscle groups in the legs.

Symptoms can include:

  • myotonia (muscle stiffness),
  • cataracts (cloudy patches in the lens inside your eye),
  • hormonal problems,
  • hypersomnolence (excessive sleeping or sleepiness), and
  • behavioural problems in children.

Myotonic MD can also cause cardiac conduction abnormalities. Your cardiac conduction system generates the electrical impulses that stimulate your heart to pump. Abnormalities can cause slow and irregular heart beats (cardiac arrhythmia). Serious problems can develop in about 60-70 per cent of people who have these abnormalities. In some cases, it can cause sudden death.

Myotonic MD can appear at any time from between birth to old age, and it affects both males and females equally. The rate of deterioration is often very slow, with little change over a long period of time. You may never experience significant disability, although your heart rate will need to be monitored for abnormalities.

Limb-girdle muscular dystrophy

The symptoms of limb-girdle MD often begin during late childhood or early adulthood. There are about 15 different varieties that affect both sexes equally.

Limb-girdle MD causes weakness in the big muscle groups in your arms and legs. It usually starts with the hip girdle and progresses to the shoulder girdle (‘girdle’ means the bones that encircle this area).

If you have limb-girdle MD, you may experience:

  • muscle weakness in your hips, thighs, and arms,
  • loss of muscle mass in the affected areas,
  • back pain, and
  • heart palpitations or cardiac arrhythmias (irregular heart beats).

The muscle weakness will create problems such as:

  • difficulty getting out of a low seat,
  • difficulty lifting objects, and
  • difficulty running.

Within 20-30 years, limb-girdle MD can progress to a level of fairly severe disability. However, the variations within this type of condition mean that your rate of progression could be better, or worse, than this.

Facioscapulohumeral muscular dystrophy

Facioscapulohumeral MD can affect both males and females. It tends to affect men slightly more than women, although the reason for this is unclear. The condition usually develops between 10 and 40 years of age and progresses slowly.

Symptoms in your child may include:

  • they sleep with their eyes slightly open,
  • they cannot squeeze their eyes tightly shut, and/or
  • they cannot purse their lips (for example to blow up balloons).

Teenagers or adults may have aches in their shoulders, rounded shoulders, or thin upper arms. As the condition progresses, it usually affects:

  • the muscles in your face (facio),
  • the muscles in your shoulders (scapula),
  • the muscles in your upper arms (humeral), and
  • the muscles of your upper back.

In around 50 per cent of people with facioscapulahumeral MD, their leg muscles will also be affected. Between 10-20 per cent of people will require a wheelchair.

Facioscapulahumeral MD can develop unevenly, so that the muscles on one side of your body are affected more than the other. Some people may not even be aware that they have the condition until they reach old age. The slow progression means that it does not usually shorten life expectancy.

Oculopharyngeal muscular dystrophy

In oculopharyngeal MD, symptoms are not usually apparent until a person is around 50 or 60 years of age. However, the abnormal gene that causes the condition will have been present since birth. It affects the muscles in your eyes (ocular) and your throat (pharyngeal).

Symptoms of oculopharyngeal MD can include:

  • ptosis (droopy eyelids),
  • dysphagia(difficulty swallowing),
  • progressive restriction of eye movement as the eye muscles are affected, and
  • limb weakness around the shoulders and hips.

As your eyelids droop, they can cover your eyes and impair your vision. It is also possible to developdiplopia (double vision). This occurs if your eye muscles are affected unevenly and your eyes start to look in slightly different directions.

The dysphagia can eventually make it hard to swallow both solid foods and liquids, and even small amounts of saliva. However, with treatment to manage the symptoms, a person’s life expectancy is not usually altered.

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Causes of muscular dystrophy

In most cases, muscular dystrophy (MD) is an inherited condition (it runs in families). It is caused by a genetic disorder (a fault with one of your genes).

Genetics

Yourgenes are units of genetic material that determine many of your body's characteristics, such as the colour of your hair and eyes. Genes consist of coiled strands of deoxyribonucleic acid (DNA) which contain molecules that store genetic information. Each cell in your body contains the same genetic information.

Genes can mutate (change) when the DNA changes, which often happens for no apparent reason. A genetic mutation alters the genetic instructions that your cells contain. If the genetic instructions change, your cells may not be able to fulfill the role they were supposed to.

Inheriting muscular dystrophy

You inherit your genes from your parents. If one, or both, of you parents have a mutated gene that causes MD, it can be passed onto you. MD can either be caused by:

  • a recessive inherited disorder - which needs two copies of the mutated gene to be passed to you, one from each parent, or
  • a dominant inherited disorder - which needs only one copy of the mutated gene to be passed to you.

Dominant inherited disorders are more common. As you only need one copy of the mutated gene, you have a 50 per cent chance of getting the condition if one of your parents has it. For recessive inherited disorders, if both of your parents are carrying the mutated gene, you have a 25 per cent chance of developing the condition.

Spontaneous gene mutations

Occasionally, spontaneous gene mutations can cause MD. This is where your genes mutate for no apparent reason, changing the way that your cells function. Spontaneous gene mutations can cause MD to develop in people who do not have a family history of the condition.

Muscular dystrophy

MD is caused by mutations in the genes that are 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.

The different types of MD are caused by mutations in different genes. This explains why some types of MD affect different muscle groups, appear at different ages, and progress at different rates.

Even within each type of MD, the mutation that has occurred in the gene can vary. This is why the symptoms of a particular type of MD can be severe in one person, but almost unnoticeable in someone else.

The specific causes of some types of MD are explained below.

Duchenne muscular dystrophy

Duchenne MD is passed on by the mother, through a faulty gene in the female X-chromosome. Girls have two X-chromosomes, one from each of their parents, whereas boys only have one X-chromosome, from their mother.

Girls will only develop Duchenne MD if they inherit two faulty copies of the X-chromosome - one from each of their parents. However, boys only need to inherit one faulty X-chromosome, from their mother, for them to develop the condition. This explains why Duchenne MD is much more common in boys.

It is also possible for Duchenne MD to develop from a spontaneous gene mutation, where neither parents have the condition.

Dystrophin

The gene that causes Duchenne MD is the gene that is responsible for the production of dystrophin. Dystrophin is a protein that is usually located just under the sarcolemma (the membrane that covers muscle fibres). Dystrophin is found in all muscles, including the heart and brain.

In Duchenne MD, a mutation in the gene that is responsible for the production of dystrophin results in very little being produced. This makes the sarcolemma very fragile. It can become damaged by muscle contractions (when the muscle shortens as you move), leading to tears in the membrane.

Calcium enters the muscle fibre through these tears and activates enzymes that break down protein in the muscles. This damages the cells in the muscles which eventually die. This causes the progressive muscle weakness that characterises Duchenne MD, and eventually leads to a complete loss of strength and mobility.

The extent to which the production of dystrophin is affected in Duchenne MD varies depending on exactly how the gene mutated. It is likely to be slightly different in everybody. This explains why symptoms can occur at different ages, be more or less severe, and affect some muscles more than others.

Becker muscular dystrophy

Becker MD is similar to Duchenne MD. It is caused by a mutation in the same gene on the X-chromosome, and affects the production of dystrophin. In Becker MD, almost normal amounts of dystrophin are produced, but there are subtle differences in its structure.

Over time, this structural difference has an adverse effect on the muscle’s function and causes disability. This explains why Becker MD is less aggressive than Duchenne MD. It has milder symptoms that usually begin at a later stage, but is still more common among boys.

Myotonic muscular dystrophy

Myotonic MD is a dominant inherited disorder that is caused by a genetic mutation in the gene that is responsible for the protein kinase. This gene contains a genetic instruction made up of three parts of DNA, which is known as a ‘triplet repeat sequence’. In people with myotonic MD, the triplet repeat sequence is repeated too many times.

Sometimes, the mutation can be quite small and only cause mild symptoms. However, in other cases, the sequence can be repeated several thousand times, causing much more severe symptoms.

Limb-girdle muscular dystrophy

There are around 15 different types of limb-girdle MD. Most of these are recessive inherited disorders, but around 14 per cent are dominant inherited disorders. Many different genetic mutations can cause limb-girdle MD, all in genes that contain information to help your muscles function.

Facioscapulohumeral muscular dystrophy

Facioscapulohumeral MD is a dominant inherited disorder. It is caused by a genetic mutation that causes a reduction, or deletion, of the genetic instructions that are contained in your cells.

There are usually many copies of a particular sequence of genetic instructions. Facioscapulohumeral MD occurs when the number of copies falls below a certain level. This mutation affects the production, or assembly, of several types of proteins in your muscles, leading to muscle weakness.

Oculopharyngeal muscular dystrophy

Oculopharyngeal MD is also a dominant inherited disorder. The abnormal gene will have been present since birth, but the effect it has on your body is so minor that symptoms do not usually appear until 50 or 60 years of age.

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Diagnosing muscular dystrophy

The methods that are used to diagnose muscular dystrophy (MD) will vary between the different types of the condition. The age at which MD is diagnosed will also vary depending on when symptoms first start to appear.

Diagnoses will usually involve:

  • investigating any symptoms,
  • discussing any family history of MD,
  • blood tests, and
  • a muscle biopsy (when a sample of tissue is removed for testing).

In the first instance, you should visit your GP if you, or your child, experience any symptoms of MD. If necessary, your GP may refer you to a hospital for further tests.

Investigating symptoms:

Your GP will need to know about any symptoms that you, or your child, have noticed, and when they began to appear. For example, you may be:

  • finding it hard to climb the stairs,
  • unable to play sports as you used to, or
  • finding it hard to lift objects.

Identifying when symptoms first appeared, and determining what muscles are affected, are both particularly useful in helping to diagnose different types of MD.

Symptoms in young children

In children, Duchenne MD is the most common type of MD. Symptoms can be present before a child is 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 might also find it difficult to stand up from sitting on the floor, and they may use what is known as the Gowers’ manoeuvre to do this. The Gowers’ manoeuvre is where a child stands up by:

  • facing the floor,
  • placing their feet wide apart,
  • lifting their bottom first, and
  • using their hands to ‘walk up’ their legs (placing their hands first on their knees, and then on their thighs).

You should visit your GP if you suspect that your child may have MD. Some of the signs that your GP will look out for in your child are listed below.

  • Your child’s posture (the way they stand).
  • Your child’s walk. Children with Duchenne MD often have a typical style of walking, which is sometimes described as ‘waddling’. Later on, they may also have a tendency to stand and walk on the front part of their foot, with their heels off the ground.
  • Whether your child has an exaggerated inward curve of their lower back. The medical term for this is lordosis, and it is also sometimes called ‘sway back’.
  • Whether your child has an outward, or sideways, curvature to their spine, known as a scoliosis.
  • Whether your child’s calves, and other leg muscles, look overly large, compared with other muscles that may be poorly developed.

Family history

If there is a history of MD in your family, it is important that you discuss this with your GP. MD is usually an inherited genetic condition, which means that it is passed on to you from your parents. If any of your close relatives have ever had MD, it 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 to determine if the type you have is a recessive or a dominant inherited disorder. This will help to narrow down exactly which type of MD you have, which will help direct your treatment where it is needed.

Blood tests

A sample of blood may be taken from a vein in your arm, or from your child, to test it for creatine kinase. This is an enzyme (a protein that speeds up chemical reactions in the body) that is usually found in muscle fibres. When muscle fibres are damaged, creatine kinase is released into the blood.

The muscle damage that is caused by MD means that the level of creatine kinase in the blood will be higher than normal. In young boys with the Duchenne MD, the amount of creatine kinase is usually at least five times greater than the highest level found in those without the condition. It can be as much as 50-100 times higher than normal.

The level of transamintates (liver enzymes) in the blood may also be higher than normal, particularly for limb-girdle MD.

Muscle biopsy

A muscle biopsy is when a small sample of muscle tissue is removed so that it can be examined under a microscope and tested for proteins. The sample will usually be taken from your leg, or your arm, depending on the type of MD that you have. The tests that are done on the sample may also vary.

Analysing the protein in the muscle can help determine which gene is causing the MD, and therefore which type of MD you have. For example, people with Duchenne MD and Becker MD will have an abnormally low level of the protein dystrophin in their muscles. Those with Duchenne MD can have less than five per cent the level of dystrophin that they should have.

Examining the muscle tissue under a microscope can help diagnose limb-girdle MD. Healthy muscle consists of closely packed, evenly-sized fibres. In people with limb-girdle MD, these fibres may be missing, different sizes, or replaced with fat.

Other tests

There are a number of other tests that 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, and direct any treatment where it is most needed. Some possibletests are explained below.

  • Amagnetic resonance imaging (MRI) scan - which uses a strong, magnetic field and radio waves to produce detailed pictures of the inside of your body. This can help to identify any pattern between the muscles that are involved, which may suggest a particular type of MD. It will also show the extent of any muscle damage.
  • Acomputerized tomography (CT) scan - involves taking a series of X-rays of your body to create a detailed image of the inside of your body. This will reveal any muscle damage.
  • A chest X-ray - can be useful for looking for respiratory (breathing) or cardiac (heart) symptoms. It will show up any abnormal enlargement of the heart, plus any fluid that is in, or around, the lungs.
  • An electromyography (EMG) test - where a needle is inserted into your muscle in order to measure the electrical activity of your muscles, both when they are resting and when they contract (shorten as you move). By measuring the muscle’s response, it is possible to see how much muscle damage has occurred.
  • An electrocardiogram (ECG) - where electrodes (flat metal discs) are attached to your arms, legs and chest in order to measure the electrical activity of your heart. This will check whether you have an irregular heartbeat and reveal any damage.
  • An echocardiogram - is an ultrasound scan of your heart using sound waves. It gives a clear picture of your heart muscles and valves so that your heart structure and function can be checked.

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Treating muscular dystrophy

At present, there is no cure for muscular dystrophy (MD), but there are a variety of treatments that can help to manage the condition.

As different types of MD can cause quite specific problems, the treatment that you receive will be tailored to your needs. As your symptoms develop, the healthcare professionals who are treating you should advise you about the available options.

New research is investigating possible future treatments, and improved genetic testing can help if you are concerned about passing the condition on to your children. See theprevention section for more information on this.

Mobility assistance

As MD progresses, it causes your muscles to weaken and you gradually begin to lose mobility and strength. These physical problems can be helped with the following:

  • exercise - to keep the muscles working in a good condition because a lack of activity can make the condition worse,
  • physiotherapy - can be useful for maintaining muscle strength, flexibility, and for preventing stiff joints, and
  • physical aids - such as a wheelchair, leg braces, or crutches can help you to stay mobile.

Glucocorticoid corticosteroids

In people with Duchenne MD, glucocorticoid corticosteroids have been shown to improve muscle strength and function for between six months and two years. For some people, they can improve:

  • the time it takes to stand up from the floor,
  • walking speed,
  • the ability to climb stairs, and
  • the ability to lift weights.

Some side effects, such as weight gain and excessive hair growth, are associated with using glucocorticoid corticosteroids.

Calcium antagonists

During Duchenne and Becker MD, calcium builds up in the weakened muscle and causes further cell damage. It was thought that a type of medication, known as calcium antagonists, may reduce the amount of calcium and therefore the damage that is caused. Unfortunately, evidence has shown that calcium antagonists have no beneficial effects for MD.

Surgery

In some severe cases of MD, surgery may be necessary to correct postural deformities. For example, if you or your child has Duchenne MD, you (or they) may develop scoliosis, which is where the spine curves to the side.

Surgery can be used to correct the scoliosis, although there have currently been no trials to evaluate its effectiveness. Surgery is aimed at:

  • halting the progression of MD,
  • improving cosmetic appearance,
  • maintaining movement and function in the upper limbs and chest, and
  • increasing life expectancy.

If you or your child may benefit from having surgery, you will be referred to a specialist to discuss the procedure and the risks involved.

Other kinds of surgery may be used to treat specific symptoms. For example, if you have ptosis (droopy eyelids) caused by oculopharyngeal MD, surgery can successfully lift the eyelids away from your eyes and restore your vision. A range of treatments are also available fordysphagia (difficulty swallowing).

Treating cardiac complications

Some types of MD can affect the cardiac (heart) muscles and the respiratory (breathing) muscles. When the condition has progressed to this stage it can become life-threatening.

It is important that your cardiac function is assessed regularly once MD has been diagnosed. For Duchenne and Becker MD, a magnetic resonance imaging (MRI) scan, or an echocardiogram (ECG), should be carried out about once a year to check for any damage.

If any damage to your heart is detected, you may be referred to a cardiologist (a heart specialist) and have tests every three months. You may also be prescribed medication to treat your heart problems. ACE inhibitors make your arteries relax, making it easier for your heart to pump blood around your body.Beta-blockers can control irregular heart beats (arrythmias) and also make it easier for your heart to work.

New research is currently investigating another medication for heart problems called angiotensin receptor blockers (ARBs) to determine whether they are able to treat the cardiac damage that is caused by MD.

In some cases of myotonic MD, apacemaker may be fitted to help correct an irregular heartbeat. A pacemaker is a small, battery-operated device that can be implanted into your chest to help your heart to beat regularly.

Support groups

As MD is a progressive condition, it can affect you emotionally, as well as physically. Support groups and organisations may help you to better understand, and come to terms with, your condition. They can also provide useful advice and support for those who care for people with MD. See the useful links section for more information, or ask your GP, or the healthcare professional who is treating you, about groups that are available locally.

New research

New ideas for MD treatments are currently being developed. For up to date information about the latest research, have a look at the useful links section. Your GP, or the healthcare professional treating you, may also know of any recent developments that might benefit you.

Speak to your GP if you are interested intaking part in a clinical trial (a form of research that tests one treatment against another).

Some examples of current research ideas are explained below.

Stem cell research

Stem cells are cells that are at an early stage of development, which means that they still 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.

Exon skipping

In the future, exon skipping may be a way of treating Duchenne and Becker MD. Exons are sections of DNA code in genes that contain information about proteins. In these types of MD, some of the exons are missing, which means the pattern of DNA is disrupted. This is why not enough of the protein dystrophin is produced.

Researchers are currently investigating ways of ‘skipping’ over the missing exons in a piece of DNA, and patching the code back together. This could mean that more dystrophin is produced and that the symptoms of the MD will be less severe.

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Preventing muscular dystrophy

In cases where muscular dystrophy (MD) develops as the result of a spontaneous gene mutation, there is nothing that can be done to prevent the condition occurring.

For prospective parents who have a family history of MD, and are worried about passing the condition on, genetic testing may help. You should speak to your GP who will be able to refer you for genetic screening and counselling.

Genetic testing

Genetic testing can be used to:

  • identify carriers of the condition, and
  • confirm a prenatal diagnosis (where a baby is diagnosed before birth).

Identifying carriers

Some types of MD are recessive inherited disorders. This means that it is possible for someone to carry a copy of the faulty gene that causes MD, but not have the condition themselves. Genetic testing can be used to determine who is 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 the blood, saliva or tissue. The DNA in the relevant gene can then be tested to find out if she is 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.

Prenatal diagnosis

Genetic testing can be used for prenatal diagnosis. This is when a baby is diagnosed with MD before it is born, usingamniocentesis (a test that is carried out during pregnancy). If you are pregnant and there is a possibility that your unborn baby could have MD, you may be offered this test.

During amniocentesis, a needle is inserted into your abdomen to take a small sample of amniotic fluid (the fluid that surrounds the foetus in the womb). This fluid contains cells that have been shed by the foetus.

The cells from the foetus can be tested to determine whether they have the genetic mutation that is responsible for MD. If they do, it is possible that the baby will have MD once it is born.

You should be aware that this kind of diagnosis is limited. A negative test result is not always reliable, and a positive result only indicates the presence of the genetic mutation that can cause MD. It will not tell you whether your child will actually experience any symptoms, or how severe they might be.

Whether you decide to have amniocentesis, and what to do when you get your results, should be discussed with your genetic counsellor or midwife.

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More Information

All the latest research, care, campaiging and fundraising news - Muscular Dystrophy Campaign


Muscular Dystrophy - Wikipedia - http://en.wikipedia.org/wiki/Muscular_dystrophy

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