What is Duchenne muscular dystrophy?

Duchenne is a condition that affects the muscles in the body. The muscles around the hips, pelvis, thighs and shoulders are usually affected first, with the skeletal muscle in the arms, legs and body affected later.

Some of the early signs and symptoms of Duchenne include:

• Delayed walking and trouble with running, climbing stairs and rising from the floor
• Appearance of large calf muscles (a result of muscle damage and build up of fibrous tissue) known as pseudo-hypertrophy
• Poor balance leading to increased chance of falling
• Walking on the toes, caused by stiffness in the tendons of the leg and foot
• Muscle degeneration in Duchenne is not associated with pain, although muscle stiffness and muscle cramps may cause pain
• Children with Duchenne often use the Gower’s manouver to stand from the floor as a result of muscle weakness in the legs. Individuals may use their hands push off the floor and then ‘walk’ their hands up their legs

More information about the diagnosis and management of Duchenne can be found in the DMD guide. 

The first muscles affected in Duchenne are usually around the hips, pelvis, thighs and shoulders and this leads to problems running, jumping and climbing stairs.

Duchenne is a progressive condition, which means it changes over time. The symptoms of the condition change as muscle wasting increases and some of the major changes include:

• Losing the ability to walk, requiring a wheelchair to move around
• Spine may start to curve (called scolliosis) as the back muscles weaken
• Upper body and arm muscles weaken

Duchenne also affects the heart muscle and causes a condition called cardiomyopathy. The muscles that control the lungs are also affected. This means that men living Duchenne often need to take heart drugs and use ventilators, first during the night time and then sometimes during the day.

It’s important to say that the changes happen gradually – nothing happens overnight.

There are established behaviour and learning risks in Duchenne. Studies have shown difficulties in some the following areas:

• Speech delay and/or language comprehension
• Learning to read – especially phonics
• Problems with counting and arithmetic
• Short term and working memory (holding something in your head while you do something else) – this is very important when you are learning to read or do maths, as well as when you are following instructions
• Emotional control

People living with Duchenne also have a higher risk of having the following diagnoses:

• Attention Deficit and Hyperactivity Disorder
• Autistic Spectrum Disorder
• Obsessive Compulsive Disorder

It is important to note that not every child with Duchenne will encounter these behavioural and learning difficulties – many individuals have no issues. However, others may experience a range of symptoms. With help and support your child can work through these issues and if you need help talking to teachers and school staff or with anything else, we can help.

There’s lots of useful information in the Guide to Duchenne Muscular Dystrophy : Information and Advice for teachers and carers, with advice from leading experts and how to work successfully with schools to ensure that your young person can achieve their potential. Nobody is looking for extra labels for children with Duchenne, but it is important that you let school and other people working with your child know about the possible risks as it may help them understand their behaviour.

Chromosomes are made from DNA, with DNA containing all the genetic information of an individual. Genes are small parts of DNA and contain messages to make proteins. Proteins are important in the structure, function and regulation of the body.

Duchenne is caused by an alteration (mutation) in the dystrophin gene which is responsible for the production of a protein called dystrophin.

Dystrophin is involved in the structure and function of muscles. It acts to protect muscle fibres during muscle contraction. The absence of dystrophin affects the muscle’s ability to function correctly, resulting in progressive muscle degeneration and loss of muscle strength.

More information about the cause of Duchenne can be found in genetics explained.

Duchenne is caused by alterations in the dystrophin gene. The dystrophin gene is responsible for the production of a protein called dystrophin.

Dystrophin has an important role in the structure and function of muscles, acting as a shock absorber, protecting muscle fibres during repeated muscle contraction or stretch. The absence of dystrophin affects the muscle’s ability to function correctly, resulting in progressive muscle degeneration and loss of muscle strength.

Dystrophin is present in all muscle cell membranes serving as a “coat hanger” around which other proteins associate. Dystrophin is a key molecule that helps form a link between the internal structure of the cell and the extracellular matrix (proteins and carbohydrates that surround a cell).

When dystrophin is absent or non-functional, the so called Dystrophin Associated Protein Complex doesn’t function correctly, interrupting a number of functions.

The role of dystrophin can be explained like a boat being held in place by an anchor. Without dystrophin the muscle is not secured, leaving it vulnerable to damage.

Figure 1 – Muscle cells are made from muscle fibres with dystrophin, along with other proteins holding the muscle fibre and muscle cell membrane together. In Duchenne muscular dystrophy the absence of dystrophin means the muscle cannot function correctly, leaving the muscle vulnerable to progressive damage and muscle wasting.

Figure 3 – Some of the results of absent or non-functional dystrophin production in Duchenne muscular dystrophy.

Duchenne is an X-linked recessive condition, primarily affecting boys. X-linked recessive conditions describe alterations in a specific gene, located on the X chromosome, causing the condition in males but not in females. Duchenne results from the alteration of the dystrophin gene.

Alterations of the dystrophin gene on the X-chromosome are inherited from the mother, who is described as being a carrier of the dystrophin gene. Carriers of the mutated dystrophin gene will not suffer from the condition themselves as they have two X chromosomes. In some cases random spontaneous alterations can occur causing Duchenne, these are not inherited from the mother.

In females the unaffected X chromosome can compensate for the mutated chromosome, with less that 1% of those with Duchenne being female.

Males only have one X and one Y chromosome; therefore males who inherit a mutated dystrophin gene on the X chromosome will have the condition. Males with the condition cannot pass the disorder on to their male offspring as males pass on their Y chromosome. Daughters who inherit an altered X-chromosome will be carriers and can pass on the mutated dystrophin gene.

Duchenne occurs across all races and cultures and can affect those with the condition in different ways, no one individual with Duchenne is the same.

Find out more in Genetics explained – Genetics and Duchenne.

Figure 1 – Inheritance pattern in Duchenne muscular dystrophy (DMD). Duchenne is an X-linked condition mainly affecting boys with girls being carriers.

If your child has been diagnosed with Duchenne muscular dystrophy please do get in contact. We have a range of useful information for parents, and will be able to answer your questions or put you in touch with people that can help and support you.

We have supported thousands of families since we were founded in 2001 as the first charity dedicated solely to improving the lives of all living with Duchenne and Becker muscular dystrophy.

We appreciate that everyone is affected by Duchenne and Becker in different ways and we are here to support you.

Call us now on 07535 498 506 or email info@actionduchenne.org

There is currently no cure for Duchenne, although steroid (glucocorticoids) treatments such as prednisolone can help slow its progression, with other potential treatments in clinical trials. Below is a summary of potential treatments in Duchenne. Action Duchenne has provided and will continue to provide funding in many of these areas. You can find out more about Potential Therapies.

Figure 1 – Possible treatment interventions in Duchenne with Action Duchenne providing funding for research in all of these areas.