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Epidermolysis Bullosa

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Background

Epidermolysis bullosa (EB) is the term used to describe a number of genetically determined disorders whose principal characteristic is skin and/or mucous membrane fragility (for example in the mouth and oesophagus). The skin has a tendency to blister in response to mechanical trauma (such as friction between the skin and clothing). According to the most recent agreement on classification there are four broad categories of EB: EB simplex (EBS), junctional EB (JEB), dystrophic EB (DEB) and mixed (Kindler syndrome). Within each of these categories there is great variability clinically.

Credits

Medical text written November 2010 by Dr Anna Martinez, Consultant Paediatrician and Dr Jemima Mellerio, Consultant Paediatric Dermatologist, Joint leads of the National Epidermolysis Bullosa Centre, Great Ormond Street Hospital, London, UK.

What are the symptoms?

Symptoms within each category can vary from relatively minor symptoms to, in the most severe forms, death in infancy.

In EBS, blistering occurs in top layer of skin, the epidermis. There are many subtypes of EBS. In the most common form, EBS localised, blistering occurs predominantly on the feet and hands and is worse in hot weather. In more severe forms, such as EBS Dowling-Meara, blistering is more widespread and severe.

Dystrophic EB is a group of disorders where blisters occur deeper, beneath the epidermis. Since the blisters are deeper, they tend to heal with scarring. Milder forms may give rise to blistering limited in extent, particularly around fingers and toes, ankles and knees, and may affect finger or toenails. The severe forms lead to more generalised blistering, which can lead to areas of chronic ulceration and scarring with resultant deformity of hands, feet and large joints.

The Herlitz form (junctional EB) is particularly severe, giving rise to chronic wounds, nail loss, failure to gain weight, difficulty in breathing and, in the vast majority of cases, death in the first year or two of life. In less severe forms of junctional EB, skin fragility is accompanied by dental enamel defects, nail abnormality and loss, and sometimes sparse hair.

What are the causes?

EB is a genetic condition where a mutation in certain genes causes absent or low levels of proteins in the skin and mucous membrane causing fragility. Fourteen responsible genes for the major forms of EB have now been identified.

How is it diagnosed?

Obtaining accurate diagnosis of the type of EB is very important to provide information for individuals, families and clinicians on likely symptoms and problems that may occur, and to be able to offer genetic counselling on the risks of EB occurring again within the family. In babies with EB without a parent or previous child having been affected, a small skin sample is usually taken. Specialised tests, electron microscopy and immunofluorescence, are done to determine the level of blistering in the skin and to identify any reduction or absence of proteins giving rise to the EB. Blood samples are also taken from the baby and parents to look for the mutation in the genes that cause EB. In older children with milder categories of EB it is sometimes possible to make the diagnosis clinically, with or without a blood test to confirm mutations.

How is it treated?

Treatment involves popping the blisters when they occur with sterile needles and the use of specialised dressings to cover raw areas. Prevention or reduction of blister formation in milder types, such as EBS localised, is focused on keeping feet cool, well-fitted ventilated shoes and painkillers. For the more severe types, skin involvement can be extensive requiring many hours a day popping blisters and dressing large raw areas. Often, in severe types of EB, other complications such as difficulty swallowing, sore eyes and dental decay are present and these are managed and treated as they occur.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
EB is a genetic disease. In some cases the inheritance is autosomal dominant but can occur less commonly in a sporadic manner. Other forms of EB, often the more severe forms, are autosomal recessively inherited.

Prenatal diagnosis
For severe forms of EB where the mutation in a previous child has been detected, prenatal diagnosis is possible from around ten weeks of pregnancy by chorionic villous sampling in around 80 per cent of cases. When the mutations are not detected in severe types of EB, it may be possible to have prenatal diagnosis later in the pregnancy with a fetal skin biopsy around 16 to 18 weeks of pregnancy. Preimplanation genetic diagnosis is also now possible for some of the most severe types of EB.

Is there support?

DEBRA

Tel: 01344 771 961
Email: debra@debra.org.uk
www.debra.org.uk

DEBRA is a Registered Charity in England and Wales No. 1084958, and in Scotland No. SC039654. It offers information and support to individuals and families affected by Epidermolysis Bullosa in the UK.  DEBRA provides an enhanced specialist nursing service and social care support, including advice, advocacy, emergency grants and access to specially adapted holiday homes. 

Group details last updated August 2014.

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