Epidermolysis bullosa (EB) describes a group of rare skin disorders that lead to fragile skin that easily blisters and tears. Blistering may also be found within the body, like blistering of the mucous membranes that surround organs and orifices (including the mouth).
EB most commonly occurs when a child inherits a faulty gene from one or both parents, but this rare disease can also follow a spontaneous mutation, meaning a gene mutation that is not found in a child’s parents.
Symptoms of EB usually become evident at a young age, and range from mild to severe.
Types of EB
EB has four major types: EB simplex (EBS), junctional EB (JEB), dystrophic EB (DEB), and Kindler syndrome. Each is largely defined by the site of blister formations within the skin layers.
EBS is the most common type of epidermolysis bullosa, marked by blistering that occurs in the epidermis, or the outermost layer of the skin. EBS usually has an autosomal dominant inheritance, meaning that a faulty gene inherited from one parent is enough to develop the disease.
Junctional EB may be severe, with blistering occurring within the basement membrane zone — a layer between the epidermis and the dermis, the skin’s lower layer. DEB is inherited in an autosomal recessive pattern, meaning it develops only when a defective gene copy is inherited from both parents.
In dystrophic EB, blistering occurs in the lamina densa, a layer of the basement membrane, and the upper dermis. JEB can be inherited in either a recessive or dominant manner.
Kindler syndrome is a very rare form of EB. Blistering can occur within and beneath the basement membrane zone, which lies between the epidermis and the dermis and keeps these two skin layers attached.
A non-genetic type of EB, called epidermolysis bullosa acquisita, occurs when the immune system wrongly attacks the type VII collagen protein, a major component of the anchoring fibrils in the epidermal basement membrane zone.
Causes of EB
Children with EB have extremely fragile skin — so fragile that even gentle rubbing can cause it to break and blister. For this reason, they have been called “butterfly” children, as their skin can seem as fragile as a butterfly’s wings.
In most cases, mutations causing the disease affect the formation of skin layers. In EBS, these defects are in genes coding for keratin proteins (in the epidermis), typically KRT5 and KRT14. People with DEB have mutations in the COL7A1 gene that encodes for type VII collagen, while those with JEB have defects in genes that promote the formation of hemidesmosomes (which help to anchor epidermal cells to those of the dermis), and the anchoring fibrils that link the epidermis to the dermis. Kindler syndrome is caused by mutations in the FERMT1 gene, which contains instructions to produce a protein with a key role in keratinocytes — the major cell type of the epidermis.
Symptoms of EB
All types of EB lead to blistering with only gentle friction or rubbing. The wounds left when fluid-filled blisters burst can be painful and become infected, and the loss of fluid from large blisters can cause dehydration in severe cases. When the wounds heal, the scar tissue that remains can cause deformities. Scars on the soles of the feet may affect mobility, and scarring on the hands and feet may fuse fingers or toes.
Nutrition can be an issue, particularly for children with blistering inside the mouth and on the lining of the esophagus. Blisters in the mouth make it painful to eat, and esophageal scarring can affect how food moves to the stomach. Blisters may also develop on the vocal cords and in the upper airways.
Other general symptoms of epidermolysis bullosa include deformed or lost fingernails and toenails, thinner skin, tiny white skin bumps called milia, dental issues such as tooth decay, and constipation.
Diagnosing EB
EB usually is diagnosed in young children, and can be diagnosed before birth in child whose parents have a disease-causing mutation. Some milder EB types can develop later in life, including in adulthood.
Doctors may suspect EB based on the appearance of a child’s skin, but lab tests are used to confirm the diagnosis. These tests include a skin biopsy, where a small sample of skin is taken to identify the layer affected by the disease.
Genetic testing is also used to diagnose EB, and to identify its specific type. These tests use a small blood sample to determine which genes carry a disease-causing mutation.
Treating EB
Without a cure for EB, the goal is to prevent blisters and to manage disease symptoms and complications. Doctors may recommend medications to ease pain and itching, or prescribe antibiotics taken orally or applied to the skin to treat infections. Sometimes surgery is necessary; for example, a surgeon may separate fused fingers or widen the esophagus to help in the movement of ingested food.
Care for children with EB largely takes place at the home. Families learn how to best “pop” blisters and apply dressings to protect wounds and promote healing. Prevention measures include taking steps to avoid any actions or choices that might aggravate the disease. Examples include dressing children in loose and easily to remove clothing, favoring soft foods in the child’s diet, and putting soft covers on car seats or hard surfaces to protect a child’s fragile skin.
Last updated: July 13, 2021
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