About DMD - Duchenne UK - Stages, symptoms, diagnosis, and genetics (2023)

Duchenne muscular dystrophy (DMD) is a progressive disease which is usually diagnosed in boys between the ages of 3 and 6.

The information on this page can help you to understand the symptoms, causes and stages of DMD.

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Signs and symptoms of Duchenne

In early stages, DMD affects the limb muscles, with the legs affected before the arms. Children with DMD are often late walkers. Muscle weakness is most noticeable when children run or get up from the floor.

Early symptoms can also include:

  • Delay in the ability to sit and stand independently
  • Large calf muscles (known as pseudohypertrophy)
  • Trouble running and jumping
  • Unusual gait when walking
  • Using the Gower’s Manouevre to get off the floor (using their hands and arms to “walk” up their own body from a squatting position).

How is Duchenne diagnosed?

If you are concerned that your child has the signs and symptoms of DMD, visit your doctor and ask for the following tests to be carried out.

If you suspect your child has DMD, a blood test can measure the amount of a substance called creatine kinase (CK) in their blood. Children with DMD always have a very high level of CK (10-100 times above normal).

CK is an enzyme foundin muscle cells.If muscles are damaged, the muscle cells are broken open and their contents find their way to the bloodstream.Highlevels can be the result of amuscleinjury, orofa chronic condition, such as DMD.

If the CK level is high, you will need further tests to see if this is because of DMD or another condition.

The second test in diagnosing DMD is a genetic test. This is taken through a blood sample.This test looks for either large changes in the gene or looks at the sequencing of the gene.

Together,these two tests can detect DMD in about 95% of patients.

A third test is required for a small number of patients. They have to have a muscle biopsy to confirm the diagnosis.

This involves taking a small piece of muscle under local anaesthetic and looking at muscle fibres under a microscope.Thisis the only way to tell the level of dystrophin in the muscle for certain.

Stages of Duchenne

There are different stages to DMD, and care needs will change over time. As more effective therapies and treatments are developed, later stages could be delayed or prevented. Each child is different, some will hit stages earlier or later than others. The information below will provide an overview of the typical stages.

DMDoften becomes noticeablewhenchildren begin to move around more. Children usually reach physical milestones like crawling or walking later.

Getting up from the floor or from lying down may be difficult – they maysupportthemselves with their hands and thighs to stand upright (called Gowers’ sign). They may walk more on their toes than other children. They may appear clumsy, fall more often, and have problemswith climbing, jumping or running. There may be slower speech development. They may appear more tired than otherchildren.

You can first see the effects of DMDin the leg muscles. Calf muscles may appear to be enlarged or swollen. This is calledpseudohypertrophy. Damaged muscle cells are replaced by fat and scar tissue,calledfibrosis.

Learning or behavioural difficulties may appear at this stage. These will range from none at all, to very slight, to more significant. These usually remain static and do not increase as the disease progresses.


Speak toyour doctor about the followingtreatment and care options:

  • a test to identify the specific genetic mutation to help choose treatment options and trials
  • diet and weight checks
  • physiotherapy and stretching
  • night splints
  • discuss starting corticosteroidsto promote muscle strength
  • supplements
  • choosing the right schools to support your child’sneeds
  • emotional support for the parents
  • advice on explaining the diagnosis to friends and family
  • referral to speech therapy (if necessary)
  • consider DEXA scans to monitor bone strength

Find out more about the current treatments and supporting therapies available for DMD.

Children at this stage will still be able to move around by themselves, but it will become increasingly difficult. As the thigh muscles weaken further, walking becomes harder. Children’s balance may be affected, which may lead to a change in posture. They may walk on the balls of their feet or their toes more than other children. Climbing up and down stairs will become harder.


Speak toyour doctor about the followingtreatment and care options:

  • walking aids:mobility scooters, walkers, or a lightweight wheelchair for longer distances
  • night splints
  • corticosteroids and supplements
  • regular echocardiogram tests for the heart
  • heart medication(ace inhibitors, beta blockers)
  • regular lung function tests(including the Forced Vital Capacity measurement and peak flow)
  • non-prescribed supplements
  • exercise– discuss with clinical staff how it is best to exercise
  • physiotherapy and stretching
  • schools – consider which will support your needs best
  • application for an Educational and Health Care Plan
  • clinical trials – often the best access point for the newest drugs
  • wheelchair, lift and stairlift funding for the home and at school
  • application for advice and grants to adapt the home
  • blue badge disability parking permit application
  • consider DEXA scans to monitor bone strength
  • cough assist machine (if required)

Find out more about the current treatments and supporting therapies available for DMD.

At this stage, young people willlose the ability to walk independently and will start using a wheelchair on a more regular basis. They will still be able to use their arms to propel themselves around, but increased weakness will start spreading to the arms and neck. Theywill continue to be able to use their arms and fingers so they will still be able to write and use a computer.

Lungs will weaken, which may lead to difficulties with breathing. Breaths may become shallower, and the ability to cough lessens. This may lead to more chest infections because it’s harder to clear mucus and germs from the chest. As breathing weakens, oxygen levels in the blood may fall, leading to tiredness, irritability, headaches on waking, inability to sleep and vivid dreams. Breathing respirators, and cough assist technologies can help with this. In time,breathing support may be needed, first overnight and then during the daytime.

The heart muscles will also be affected. This is called cardiomyopathy, and there are treatments available to help.


Speak toyour doctor about the followingtreatment and care options:

  • physiotherapy to remove mucus from the chest
  • noninvasive ventilation
  • techniques to increase the air flow into the lungs
  • breathing respirators
  • hoists
  • monitor for scoliosis
  • bone drugs (bisphosphonate treatments)
  • regular echocardiogram tests for the heart
  • heart medication (ace inhibitors, beta blockers)
  • promoting independence
  • support for frustration, anger and emotional distress
  • respite for carers
  • ask consultant about a sleep study (if sleepy in the day or headaches)
  • DEXA scans to monitor bone strength

Find out more about the current treatments and supporting therapies available for DMD.

Duchenne UK are here for you as your child grows up – read our guidance on supporting your teenager with DMD.

Life expectancy is improving so there are more people living with DMD in their twenties, thirties, and forties.

Young adults may have difficulty chewing and swallowing food, this is called dysphagia. If it is severe, a feeding tube into the stomach may be needed. They will need help eating, drinking, going to the toilet, dressing, washing and being moved into bed and being turned in bed.

Upper body mobility will be impaired, but many young adults continue to be able to use their fingers well into adult life. Their ability to talk usually remains good, andcan be helped with speech therapy and speech amplification equipment. Their ability to be able to think for themselves is unimpaired and, with support, adults withDMDcan play an active part in society.


Speak toyour doctor about the followingtreatment and care options:

  • good access to computer technology
  • discussions about implementing independent living
  • finding and keeping a job
  • identifying and managing depression
  • encouragement of emotional support outside the family in friendship groups.

Duchenne UK is not only funding treatments for earlier stages of DMD but investing in improving quality of life for adolescents and adults living with DMD through better care, treatments and technologies. Read more about the research we fund.

Visit the Pathfinders Neuromuscular Alliance website for advice and support for adults living with DMD.

FAQs about Duchenne

For an explanation of scientific terminology, visit our DMD research glossary

DMD is a genetic disease. Children can either inherit DMD from a parent, or it can be the result of a random genetic mutation.

DMD occurs when there is a fault on the dystrophin gene. This is the gene that the body needs to produce a protein called dystrophin, which is essential for maintaining muscle strength and function.

The dystrophin gene is the largest gene in the body. It is made up of 79 active pieces of DNA, called exons. All 79 of these exons are joined together in a sequence. This sequence communicates the information that the body needs to make the dystrophin protein.

There are three errors, called mutations, that can prevent any or enough dystrophin being made by the body:

  1. Exon deletion – this means that one or more exons in the dystrophin gene is missing. This is the cause of around 70% of cases.
  2. Exon duplication – around 10% of cases are caused by one or more exons having extra copies in the dystrophin gene.
  3. Other small changes, such as tiny deletions of genetic code. These cause around 20% of cases.

Potential treatments that tackle the root causes of Duchenne includegene therapy.Research is currently underway to investigate how to create a working dystrophin gene and place it in the body.

All the genes in our bodies are packaged into ‘groups’ called chromosomes. These chromosomes are inherited from our father and mother.

Females have two X chromosomes (one X from their mother and one X from their father). Males have one X chromosome (from their mother) and one Y chromosome (from their father).

The dystrophin gene is only located on X chromosomes. Duchenne is much more common in males because they only have one X chromosome. Iftheir dystrophin gene is faulty, they will not have a ‘back up’ dystrophin gene on their other chromosome.

In two thirds of cases, the faulty dystrophin gene is passed from the mother to the child. These women are called ‘carriers’ because they carry the DMD gene,but do not have DMD themselves.

In one third of cases, a spontaneous mutation happens at the beginning of the pregnancy.

No one is to blame for either inherited genes or spontaneous mutations. Genes are very complicated and sometimes they go wrong.

Currently, people with DMD live into their twenties and thirtieson average, with some living into their forties and fifties. However, it is difficult to say what the life expectancy of a child with DMD will be.

Access to better treatments and care will affect average life expectancy. Duchenne UK and other charities across the world are funding research into new treatmentsand investing in better care to extend lives and improve quality of life.

Find out more about the research we fund.

DMD is very rare in females, but it can happen. It is estimated that 1 in 50 million girls are born with DMD.

Females can only develop DMD if they have a fault on their dystrophin genes on both their X chromosomes. This can only happen if:

  • The girl inherits a faulty dystrophin gene on one of her X chromosomes from her mother and also develops a spontaneous mutation in her other X chromosome
  • The girl’s healthy dystrophin gene on one X chromosome becomes ‘switched off’ by a process called X-linked inactivation because she has inherited a faulty dystrophin gene on her other X chromosome
  • The girl’s father is a man with DMD and her mother is a woman who carried a defective DMD gene (‘a carrier’)
  • The girl develops spontaneous mutations in the DMD gene on both of her X chromosomes

Women and girls can also becarriersor manifesting carriers of DMD.

Some female carriers of the disease (approximately 8%) are ‘manifesting carriers’, meaning they show some milder symptoms of the disease.

This is not the same as having DMD, but these girls and women will produce reduced amounts of dystrophin.

Manifesting carrier symptoms can include:

  • Fatigue
  • Mild muscle weakness
  • Cramping

Female carriers also have an increased risk of heart problems. If you have been diagnosed as a carrier, you should have your heart checked every 3 to 5 years.

Genetic testing can determine whether awomanisdefinitely acarrier of DMD, or if she is unlikely to be a carrier.

If you are concerned that you may be a carrier of DMD, speak to your doctoror a genetic counsellorabout genetic testing.

Not all mothers of children with DMD are carriers. 30% of cases are caused by spontaneous genetic mutations.

The key protein for muscle function that is missing in DMD, dystrophin, is also believed to have a role in brain development. People with DMD are more likely to have learning and behavioural difficulties, such as dyslexia, attention-deficit/hyperactivity disorder (ADHD), or autism spectrum disorders (ASD). However, not everyone with DMD has these difficulties.

Research into DMD and the brain is ongoing.

If you are concerned that your child has learning and behavioural difficulties associated with DMD, find out how to get support with their education.

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How can Duchenne be treated

Current treatments and supporting therapies for DMD can help to ease the symptoms of the disease.

Duchenne UK is funding research into new treatments that could have greater impact and more acceptable side effects.

Find out more

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If your loved one has DMD, we are here to support you from the point of diagnosis into adulthood.

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