Duchenne muscular dystrophy (DMD)

Duchenne muscular dystrophy (DMD) is a muscle wasting condition. It causes muscle weakness that gets worse over time, and it usually affects only males.

The cause is a lack of a protein called dystrophin. Without it, muscle fibres break down. Fibrous or fatty tissue takes their place, and the muscle slowly becomes weaker.

DMD is a severe type of MD and often shortens life expectancy. Most people with DMD will reach adulthood. They are, however, more likely to die from heart or respiratory failure before or during their 30's.

Symptoms of Duchenne muscular dystrophy (DMD) are unusual from birth. Most often the first signs show up between 1 and 2 years of age.

A child with DMD might have:

• difficulties running, jumping and climbing stairs
• difficulty getting up from the floor
• a waddling gait (walking on their toes with an arched lower back)
• difficulty walking as fast or as far as other children
• a tendency to fall more than other children
• learning and behavioural difficulties
• learning to speak later than usual

Your child might also find it hard to stand up from a seated position. Some children use the Gowers' manoeuvre to get up. They do this by:

• facing the floor
• placing their feet wide apart
• lifting their bottom first
• walking their hands from their knees to their thighs to a standing position

Contact a doctor if you or your child has:

• muscle weakness
• mobility problems

Duchenne muscular dystrophy (DMD) is a type of sex linked muscular dystrophy, also called X-linked. To see why, it helps to know how chromosomes differ between males and females. Chromosomes are long threadlike structures of DNA. Males have one X and one Y chromosome, while females have two X chromosomes.

A sex linked disorder is caused by a mutation in a gene on the X chromosome. Males have only one copy of that gene, so they're affected if it is mutated.

Females have 2 copies of the X chromosome, so they're less likely to develop an X-linked condition like DMD. The healthy copy can usually compensate for (mask) the mutated one. Females can still be affected by X-linked disorders, but the symptoms are likely to be less severe.

There are several methods used to diagnose muscular dystrophy, and Duchenne muscular dystrophy (DMD) is no different. Diagnosis might involve:

• looking into your symptoms
• your family history
• a physical exam
• blood tests
• electrical tests on the nerves and muscles
• a muscle biopsy (where a small sample of tissue is removed for testing)

A blood test will normally be enough to confirm a diagnosis of DMD.

There are treatments that help with many of the symptoms of Duchenne muscular dystrophy.

Corticosteroid medicine (steroids) can help improve your muscle strength and function, and this can slow down the progress of muscle weakness. Steroids come as tablets or in liquid form.

Ataluren (Translarna) is used for some children with Duchenne MD who can still walk. It's only effective for children with MD caused by a specific gene mutation. Ataluren can help slow down the progress of muscle weakness. It's prescribed as a sachet of granules, which you mix into liquids or food such as yoghurt and then eat.

A child with DMD could need a wheelchair by the time they're 11 years old. At first it might only be for long distances, but later it's likely to be needed full time. At this stage they might also have difficulty with other muscles, for example raising their arms above shoulder height.

Your child might benefit from splints or a spinal brace to help with their posture and mobility.

Duchenne MD can cause scoliosis. Surgery might be used to correct scoliosis or to stop it getting worse.

Many people with DMD develop dilated cardiomyopathy, which affects the heart muscles. The faulty gene also affects the heart muscles. It causes the heart's chambers to enlarge and the heart muscle to get thinner.

If you have Duchenne MD, you'll have regular electrocardiograms (ECGs) to examine your heart rhythm. You'll also need an echocardiogram. An MRI scan might be carried out to check for heart problems.

You'll see a cardiologist (heart specialist) for further tests and monitoring. The cardiologist will prescribe medicine to help improve your heart function. You might also have an ICD (implantable cardioverter defibrillator) inserted to help with your heart function.

It's likely your child will have breathing problems and will need a machine to help them breathe at night and sometimes during the day.

With older children, cough assist machines can help them cough up and remove secretions (phlegm). Using an Ambu bag can help to preserve their chest wall muscle strength.

Children with DMD are at risk of frequent chest infections. These might be treated with antibiotics.

Your child might have difficulty feeding. A nasogastric tube or gastrostomy tube might be inserted to help with feeding.

Bladder problems are common in people with muscle disorders like muscular dystrophy.

You might experience urinary incontinence, where you pee by accident. This is often caused by weakness of the pelvic floor muscles, combined with weakness of the core muscles.

You're more likely to experience urinary incontinence if you:

• have poor mobility
• spend a lot of time sitting down

Pelvic floor exercise may be helpful. An urgent need to pee can sometimes be helped with medicine.

You might experience bowel problems like:

• chronic constipation
• diarrhoea with little warning
• bowel incontinence

If you drink less water than is recommended to avoid going to the toilet during the day, this could cause dehydration. That can make constipation worse and contribute to bowel problems.

Using a gentle laxative like Lactulose regularly during the week may help.

You might want to consider hospice care to help you or your child cope with the condition. The hospice can offer help like:

• counselling
• pain management