Duchenne muscular dystrophy is a condition which causes muscle weakness. It starts in childhood and may be noticed when a child has difficulty standing up, climbing or running. It is a genetic condition and can be inherited. It usually affects only boys, although girls may carry the Duchenne gene. Boys with Duchenne muscular dystrophy should have regular check-ups and physiotherapy from childhood, and are likely to need increasing help and treatments from about the age of nine years.
What is Duchenne muscular dystrophy?
Duchenne muscular dystrophy (DMD) is an inherited (genetic) condition which affects the muscles, causing muscle weakness. It is a serious condition which starts in early childhood. The muscle weakness is mainly in the 'proximal' muscles, which are those near the trunk of the body, around the hips and the shoulders. This means that fine movements, such as those using the hands and fingers, are less affected than movements like walking.
The muscle weakness is not noticeable at birth, even though the child is born with the gene which causes it. The weakness develops gradually. It usually shows up in early childhood. Symptoms are mild at first, but increase as the child gets older.
The name Duchenne comes from the doctor who first studied this condition.
How common is Duchenne muscular dystrophy?
About 1 in 3,500 boys in the UK are born with DMD. There are other types of muscular dystrophy too, which are rarer. See separate leaflet called Muscular Dystrophies - An Overview for more detail about other types of muscular dystrophy.
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What causes Duchenne muscular dystrophy?
The cause is a genetic change which affects the muscles. Muscles contain a chemical (protein) called dystrophin, which is necessary for muscles to function properly. People with DMD have a shortage of dystrophin in their muscles. The lack of dystrophin leads to muscle fibre damage and a gradual weakening of the muscles. The shortage of dystrophin is caused by a faulty gene.
How does a faulty gene cause DMD?
The body is made of cells, and each cell has a 'control centre' which contains genes. The genes are made of DNA. The genes control how the cells make chemicals (proteins). Every cell contains many different genes and makes many different proteins. One of these proteins is the dystrophin protein which is involved in DMD.
In DMD there is a fault in the the gene which makes dystrophin. So the muscle cells cannot make dystrophin (or make only a little of it). This leads to muscle damage, as explained above.
How is Duchenne muscular dystrophy inherited?
Each person inherits a set of genes from their father and another set from their mother. The genes have been copied from the parents' cells into the child's cells.
Genes are found on 'chromosomes', rather like houses on a street. The DMD gene is located on a chromosome called the X chromosome. Boys have one X chromosome and one Y chromosome; girls have two X chromosomes.
DMD is inherited in a pattern called 'X-linked inheritance'. The DMD gene is 'carried' by women, but does not usually cause problems in girls or women (with rare exceptions, below). This is because of there being two X chromosomes in women: one X chromosome has the 'faulty' DMD gene, and the other X chromosome has a normal gene, which compensates for the faulty one.
In contrast, boys with the DMD gene do not have a second X chromosome and so they cannot compensate for the faulty gene. Therefore, boys with the DMD gene always have symptoms of the disease.
The DMD gene can be passed on from parent to child. For a woman who carries the DMD gene, there is a 1 in 2 chance that her sons will have DMD, and a 1 in 2 chance that her daughters will carry the gene.
x-linked pattern of inheritance
If my child has DMD, does that mean that other family members have the DMD gene?
Not necessarily. In about half of DMD cases, the fault in the child's gene has not come from the parent. Instead, the fault has arisen while the child's cells were being formed. This can happen if a 'mistake' is made when the parents' genes are copied into the cells which will make the child.
About half the children with DMD will not have family members carrying the gene. DNA testing and specialised genetic advice can help you find out whether the Duchenne gene is carried by other members of the family.
What are the symptoms of Duchenne muscular dystrophy?
The symptoms usually start around age 1-3 years. Parents may notice:
The child having difficulty with walking, running, jumping and climbing stairs. Walking may look different with a 'waddling' type of walk. The boy may be late in starting to walk (although many children without DMD also walk late).
When you pick the child up, you may feel as if he 'slips through your hands', due to looseness of the muscles around the shoulder.
The calf muscles may look bulky, although they are not strong.
As he gets older, the child may use his hands to help him get up, looking as if he is 'climbing up his legs'. This is called 'Gower's sign'.
Some boys with DMD also have a learning difficulty. Usually this is not severe.
Sometimes, a delay in development may be the first sign of DMD. The child's speech development may also be delayed. Therefore, if you have a boy whose development is delayed, you may be offered a screening test for DMD. However, DMD is only one of the possible causes of developmental delay - there are many other causes not related to DMD.
How is Duchenne muscular dystrophy diagnosed?
The diagnosis may be suspected because of the child's symptoms (above). When looking for signs of DMD, it is important to watch the child running and getting up from the floor - the muscle weakness is more noticeable during these activities.
Tests are needed before DMD can be diagnosed. The first step in making the diagnosis is a blood test. This tests for creatine kinase. Children with DMD always have a very high level of creatine kinase (about 10-100 times normal). Therefore if a child's creatine kinase level is normal, then DMD is ruled out. If the creatine kinase level is high, further tests are needed to see whether this is due to DMD or to some other condition.
The next step in diagnosing DMD involves either a muscle biopsy and/or genetic tests:
A muscle biopsy involves taking a small sample of a muscle, under local anaesthetic. The sample is examined under a microscope using special techniques to look at the muscle fibres and the dystrophin protein.
Genetic tests are done using a blood sample. The DNA in the blood is tested to look at the dystrophin gene. This test can diagnose most cases of DMD.
What is the treatment for Duchenne muscular dystrophy?
There is no cure for DMD at present. However, treatments can help. Here is an outline of the treatment you/your child may be offered. The treatment is described here according to age group, although there will be some overlap and the ages given are only a rough guide.
Pre-school age
Usually, at this stage, your child will be well and not need much treatment. What you will usually be offered is:
Information about DMD. You may wish to be in touch with patient support groups or other families with DMD (see 'Further help & information', below).
Referral to a specialist team so that your child's health can be monitored. The specialist team may include a doctor who specialises in the medical care of children (a paediatrician), or a specialist in muscle and nerve conditions (a neurologist), and a physiotherapist and specialist nurse.
Advice about the right level of exercise for your child.
Genetic advice for the family. You may wish to have tests to see whether anyone else in the family has the DMD gene. This may be important to families who are thinking of having more children.
Age 5-8 years
At this age, some support may be needed for the legs and ankles. For example, using nighttime ankle splints, or with a longer brace called a knee-ankle-foot orthosis (KAFO).
Treatment with medication called corticosteroids (or steroids) can help to maintain the child's muscle strength. This involves taking medication such as prednisolone or deflazacort as a long-term treatment, either continuously or in repeated courses. Steroid medication can have side-effects, so the pros and cons of this treatment need to be weighed up, and the treatment needs to be monitored for side-effects. See separate leaflet called Oral Steroids for more details.
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8 years to late teenage years
At some time after the age of 8 years, the child's leg muscles become significantly weaker. Walking gradually gets more difficult, and a wheelchair is needed. The age at which this happens varies from person to person. Often it is around age 9-11 years, although with corticosteroid treatment, some boys can walk for longer.
After the child starts needing a wheelchair, this is also the time that complications tend to begin, so it is important to monitor the boy's health and to treat any complications early (see below). Your child will need regular check-ups. This may involve different specialists - for example, heart and lung checks, orthopaedic care for bones and joints, physiotherapists, and dieticians.
Practical support and equipment will be needed at this stage - for example, wheelchairs and adaptations to the child's home and school. Occupational therapists can advise about this. Various services can assist with equipment, care, holidays and breaks. There is usually provision from local health and social services. Also, various charities which can assist with equipment, holidays and other forms of care.
Counselling and emotional support for you and/or
Duchenne muscular dystrophy is a condition which causes muscle weakness. It starts in childhood and may be noticed when a child has difficulty standing up, climbing or running. It is a genetic condition and can be inherited. It usually affects only boys, although girls may carry the Duchenne gene. Boys with Duchenne muscular dystrophy should have regular check-ups and physiotherapy from childhood, and are likely to need increasing help and treatments from about the age of nine years.
What is Duchenne muscular dystrophy?
Duchenne muscular dystrophy (DMD) is an inherited (genetic) condition which affects the muscles, causing muscle weakness. It is a serious condition which starts in early childhood. The muscle weakness is mainly in the 'proximal' muscles, which are those near the trunk of the body, around the hips and the shoulders. This means that fine movements, such as those using the hands and fingers, are less affected than movements like walking.
The muscle weakness is not noticeable at birth, even though the child is born with the gene which causes it. The weakness develops gradually. It usually shows up in early childhood. Symptoms are mild at first, but increase as the child gets older.
The name Duchenne comes from the doctor who first studied this condition.
How common is Duchenne muscular dystrophy?
About 1 in 3,500 boys in the UK are born with DMD. There are other types of muscular dystrophy too, which are rarer. See separate leaflet called Muscular Dystrophies - An Overview for more detail about other types of muscular dystrophy.
Related articles
q
Muscular Dystrophies - An Overview
Topical Steroids
Preventing Steroid-induced Osteoporosis
See more articles »
What causes Duchenne muscular dystrophy?
The cause is a genetic change which affects the muscles. Muscles contain a chemical (protein) called dystrophin, which is necessary for muscles to function properly. People with DMD have a shortage of dystrophin in their muscles. The lack of dystrophin leads to muscle fibre damage and a gradual weakening of the muscles. The shortage of dystrophin is caused by a faulty gene.
How does a faulty gene cause DMD?
The body is made of cells, and each cell has a 'control centre' which contains genes. The genes are made of DNA. The genes control how the cells make chemicals (proteins). Every cell contains many different genes and makes many different proteins. One of these proteins is the dystrophin protein which is involved in DMD.
In DMD there is a fault in the the gene which makes dystrophin. So the muscle cells cannot make dystrophin (or make only a little of it). This leads to muscle damage, as explained above.
How is Duchenne muscular dystrophy inherited?
Each person inherits a set of genes from their father and another set from their mother. The genes have been copied from the parents' cells into the child's cells.
Genes are found on 'chromosomes', rather like houses on a street. The DMD gene is located on a chromosome called the X chromosome. Boys have one X chromosome and one Y chromosome; girls have two X chromosomes.
DMD is inherited in a pattern called 'X-linked inheritance'. The DMD gene is 'carried' by women, but does not usually cause problems in girls or women (with rare exceptions, below). This is because of there being two X chromosomes in women: one X chromosome has the 'faulty' DMD gene, and the other X chromosome has a normal gene, which compensates for the faulty one.
In contrast, boys with the DMD gene do not have a second X chromosome and so they cannot compensate for the faulty gene. Therefore, boys with the DMD gene always have symptoms of the disease.
The DMD gene can be passed on from parent to child. For a woman who carries the DMD gene, there is a 1 in 2 chance that her sons will have DMD, and a 1 in 2 chance that her daughters will carry the gene.
x-linked pattern of inheritance
If my child has DMD, does that mean that other family members have the DMD gene?
Not necessarily. In about half of DMD cases, the fault in the child's gene has not come from the parent. Instead, the fault has arisen while the child's cells were being formed. This can happen if a 'mistake' is made when the parents' genes are copied into the cells which will make the child.
About half the children with DMD will not have family members carrying the gene. DNA testing and specialised genetic advice can help you find out whether the Duchenne gene is carried by other members of the family.
What are the symptoms of Duchenne muscular dystrophy?
The symptoms usually start around age 1-3 years. Parents may notice:
The child having difficulty with walking, running, jumping and climbing stairs. Walking may look different with a 'waddling' type of walk. The boy may be late in starting to walk (although many children without DMD also walk late).
When you pick the child up, you may feel as if he 'slips through your hands', due to looseness of the muscles around the shoulder.
The calf muscles may look bulky, although they are not strong.
As he gets older, the child may use his hands to help him get up, looking as if he is 'climbing up his legs'. This is called 'Gower's sign'.
Some boys with DMD also have a learning difficulty. Usually this is not severe.
Sometimes, a delay in development may be the first sign of DMD. The child's speech development may also be delayed. Therefore, if you have a boy whose development is delayed, you may be offered a screening test for DMD. However, DMD is only one of the possible causes of developmental delay - there are many other causes not related to DMD.
How is Duchenne muscular dystrophy diagnosed?
The diagnosis may be suspected because of the child's symptoms (above). When looking for signs of DMD, it is important to watch the child running and getting up from the floor - the muscle weakness is more noticeable during these activities.
Tests are needed before DMD can be diagnosed. The first step in making the diagnosis is a blood test. This tests for creatine kinase. Children with DMD always have a very high level of creatine kinase (about 10-100 times normal). Therefore if a child's creatine kinase level is normal, then DMD is ruled out. If the creatine kinase level is high, further tests are needed to see whether this is due to DMD or to some other condition.
The next step in diagnosing DMD involves either a muscle biopsy and/or genetic tests:
A muscle biopsy involves taking a small sample of a muscle, under local anaesthetic. The sample is examined under a microscope using special techniques to look at the muscle fibres and the dystrophin protein.
Genetic tests are done using a blood sample. The DNA in the blood is tested to look at the dystrophin gene. This test can diagnose most cases of DMD.
What is the treatment for Duchenne muscular dystrophy?
There is no cure for DMD at present. However, treatments can help. Here is an outline of the treatment you/your child may be offered. The treatment is described here according to age group, although there will be some overlap and the ages given are only a rough guide.
Pre-school age
Usually, at this stage, your child will be well and not need much treatment. What you will usually be offered is:
Information about DMD. You may wish to be in touch with patient support groups or other families with DMD (see 'Further help & information', below).
Referral to a specialist team so that your child's health can be monitored. The specialist team may include a doctor who specialises in the medical care of children (a paediatrician), or a specialist in muscle and nerve conditions (a neurologist), and a physiotherapist and specialist nurse.
Advice about the right level of exercise for your child.
Genetic advice for the family. You may wish to have tests to see whether anyone else in the family has the DMD gene. This may be important to families who are thinking of having more children.
Age 5-8 years
At this age, some support may be needed for the legs and ankles. For example, using nighttime ankle splints, or with a longer brace called a knee-ankle-foot orthosis (KAFO).
Treatment with medication called corticosteroids (or steroids) can help to maintain the child's muscle strength. This involves taking medication such as prednisolone or deflazacort as a long-term treatment, either continuously or in repeated courses. Steroid medication can have side-effects, so the pros and cons of this treatment need to be weighed up, and the treatment needs to be monitored for side-effects. See separate leaflet called Oral Steroids for more details.
Related discussions
E
balwantFamily inheritance of Duchenne Muscular Dystrophy balwant 0 replies
IkeelayuWhat is causing the inflammation in my brain Ikeelayu 2 replies
Gueststeroids Guest 7 replies
Start a discussion »
8 years to late teenage years
At some time after the age of 8 years, the child's leg muscles become significantly weaker. Walking gradually gets more difficult, and a wheelchair is needed. The age at which this happens varies from person to person. Often it is around age 9-11 years, although with corticosteroid treatment, some boys can walk for longer.
After the child starts needing a wheelchair, this is also the time that complications tend to begin, so it is important to monitor the boy's health and to treat any complications early (see below). Your child will need regular check-ups. This may involve different specialists - for example, heart and lung checks, orthopaedic care for bones and joints, physiotherapists, and dieticians.
Practical support and equipment will be needed at this stage - for example, wheelchairs and adaptations to the child's home and school. Occupational therapists can advise about this. Various services can assist with equipment, care, holidays and breaks. There is usually provision from local health and social services. Also, various charities which can assist with equipment, holidays and other forms of care.
Counselling and emotional support for you and/or
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