Muscular dystrophy

What is muscular dystrophy?

Muscular dystrophies are a group of more than 20 different genetic neuromuscular disorders, some more debilitating than others.

Each type differs in its clinical course, some are more severe than others. The most common, Duchenne muscular dystrophy (DMD) affects one in 4,000 boys.

There is a problem in the chromosome that codes for a protein called dytrophin which maintains the integrity of the muscle cell wall. Eventually irreversible destruction of the muscle cells occurs.

Symptoms

Boys with DMD are generally normal at birth. Their motor development starts normally and most walk at the normal age of 12 months.

From the second year of life, they may develop a waddling gait, lack a spring to their step and have problems climbing stairs.

In early school years, it may just seem that they are slower and more clumsy than their peers. The disease progresses such that the majority will be wheelchair bound by 10-14 years.

They develop problems with their breathing and may need ventilatory support. Problems with the heart muscle also occur. Most boys die in their late teens or early twenties.

All types of MD gradually worsen, but the speed and degree of disability varies. Many people are able to continue managing independently, while others may need full-time help and care.

Causes and risk factors

Muscular dystrophies are inherited. Each disease is transmitted by a different genetic trait.

DMD is inherited in an X-linked recessive transmission. That means that females may be carriers but do not have any symptoms (very occasionally they do).

A female carrier has a 50 per cent chance of transmitting the faulty gene onto her children. If that is the case and her child is a boy, he will have DMD, if it is a girl, she will be a carrier and may pass the disease onto her sons.

About 30 per cent of cases are due to new mutations, meaning that their mother was not a carrier.

Treatment and recovery

There's no cure and, although a great deal can be done to help limit the effects of MDs, there's no way to stop the loss of muscle cells. Intensive research is being carried out around the world to find a cure.

Existing treatments aim to control symptoms, such as muscle spasm, and enable people to have a good quality of life. They include muscle exercises, because inactivity can worsen the disease, physiotherapy to help maintain muscle strength and flexibility, and physical aids such as braces or wheelchairs to maintain mobility.

It is also important to pay attention to nutritional status and respiratory function. When respiratory function deteriorates, ventilatory support may be needed.

With any progressive disease it's important to be aware of the emotional effects the condition can have. Support groups and organisations help many people come to terms with their situation. Emotional support is important for carers, too.

Genetic counselling, prenatal diagnosis by chorionic villus sampling, and antenatal screening of families with MDs provides an opportunity to prevent these diseases being passed on to children. In some areas, Duchenne muscular dystrophy is screened for in the neonatal blood spot (Guthrie card).

Advice and support

• Muscular Dystrophy Campaign
• Tel: 020 7720 8055
• Email: info@muscular-dystrophy.org
• Website: www.muscular-dystrophy.org

• Duchenne Family Support Group
• Helpline: 0870 606 1604
• Email: info@dfsg.org.uk
• Website: www.dfsg.org.uk