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Duchenne Muscular Dystrophy

Background

Duchenne muscular dystrophy (DMD) is a muscle wasting condition, which gets worse over time. Muscle weakness occurs because of a genetic defect that prevents dystrophin, a protein in muscle, functioning correctly. The affected gene resides on the X chromosome, so only boys are affected. About 1,000 boys are born each year in the UK with DMD.

Credits

Medical text written September 2011 by Dr M Scoto Clinical Research Associate, and Dr A Manzur, Consultant Paediatric Neurologist, Dubowitz Neuromuscular Centre, UCL Institute of Child Health and Great Ormond Street Hospital, London, UK.

What are the symptoms?

In DMD, the first signs of muscle weakness typically occur before the age of four years. Rising from the floor, walking, running, jumping and climbing stairs are difficult. If untreated, most boys lose the ability to walk by ten years of age and need to use a wheelchair. This is due to a combination of muscle weakness and contractures (tightness of muscle affecting joint movement) in the ankles, knees and hips. Boys in a wheelchair are at high risk of developing spinal curvature, which can eventually develop into scoliosis. Some boys with DMD may have learning or behavioural difficulties (see entry Learning Disability).

Over time, the heart and respiratory muscles are also affected and this becomes a clinical problem usually in the teenage years. Sometimes there is respiratory failure, which is often demonstrated by difficulty breathing at night.

If untreated, limbs, breathing and heart muscle weakness become severe and this limits life expectancy.

Cardiomyopathy can develop in individuals with DMD, usually after ten years of age. It is recommended that an echocardiogram (heart ultrasound scan) be done every two years till age ten years, and then yearly after so any abnormality can be detected and treated.

How is it diagnosed?

A high level of the enzyme creatine kinase (CK) can indicate DMD. Further confirmatory testing in a family where there are no other cases of DMD, will involve muscle biopsy to assess muscle structure. Genetic testing is undertaken to offer confirmation of the mutation causing the condition.

How is it treated?

To date, there is no cure for DMD. Treatment to help reduce the symptoms improves quality of life and prolongs survival.

To prevent the progression of DMD treatment with glucocorticosteroids (a type of steroid), is routine. This treatment can help retain movement, prevent respiratory failure and delay scoliosis.

A regular programme of physiotherapy is essential to reduce contractures and promote mobility. Bracing can reduce scoliosis, but very often spinal surgery is required if the curvature gets worse. Facial or nasal mask ventilation may be used to assist with night-time breathing.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
DMD usually occurs as the result of a sporadic mutation. In some cases the mother of the affected child is a carrier of the condition. Mothers of children with DMD should be offered genetic counselling and a test to find out whether they are carrier for the DMD mutation.

Prenatal diagnosis
Prenatal testing is available via amniocentesis after 15 weeks of pregnancy or chorionic villus sampling between 10 and 13 weeks of pregnancy.

Is there support?

Action Duchenne

Tel: 020 8556 9955
Email: info@actionduchenne.org
www.actionduchenne.org

The Group is a Registered Charity in England and Wales No. 1101971. It provides information and support for families with a child with Duchenne Muscular Dystrophy. Action Duchenne funds research, campaigns for the best standards of care to be made available for all living with Duchenne, and runs education and transition projects for young people.

Group details last updated January 2016.

Duchenne Family Support Group

Helpline: 0800 121 4518 
Email: info@dfsg.org.uk
www.dfsg.org.uk

The Group is a Registered Charity in England and Wales No. 1128653. It provides information and support for families with children diagnosed with Duchenne Muscular Dystrophy. The Group offers holidays and events to bring families together for mutual support and to share information and experiences.

Group details last updated January 2016.

Support for Duchenne muscular dystrophy is also available from the Muscular Dystrophy Campaign (see entry Congenital Muscular Dystrophy).

 

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