Epidermolysis bullosa (EB) is caused by a fault, or mutation, in the keratin or collagen gene, and it affects the connective tissues.
Research has previously suggested that EB affects 19 people in every million in the United States, and it is thought that 500,000 people worldwide may be living with EB. The risk is the same, regardless of gender and ethnicity.
The skin of patients with EB is extremely fragile. Even very slight friction may cause blisters as layers of skin move independently and separate.
Severity can range from mild to life-threatening. In mild EB, the blistering is confined to hands and feet, but severe EB affects the whole body, and complications such as infection, feeding difficulties, and loss of nutrients through the skin can be fatal.
Wounds heal very slowly and there can be significant scarring, physical deformity, and disability. People with severe EB have a significantly higher risk of developing skin cancers.
There is no cure. Treatment focuses on relieving the symptoms of pain, infection risk, and complications.
Effects on the body
In people with EB, friction between the outer and inner layers of skin leads to blistering.
Normal human skin has two layers, the epidermis, which is the outer part, and the dermis, or the inner part.
Normally, there are protein anchors between the layers, made of collagen, and they prevent the two layers from shearing, or moving independently from one another.
People with EB do not have these protein anchors, so when there is any friction on the skin, the two layers rub against each other and separate, resulting in painful sores and blisters.
The blistering can also occur in the inner mucous membranes, such as the mouth and esophagus. This makes it almost impossible to eat solids.
Patients whose mucous membranes are also affected may find urinating painful.
Younger people with EB are sometimes called "butterfly children," because their skin is said to be as fragile as the wings of a butterfly.
There are three major types of EB.
- The most common type of EB is epidermolysis bullosa simplex (EBS). Around 70 percent of EB cases are of this type, in which blisters form on the outer layer of the skin.
- Dystrophic epidermolysis bullosa (DEB) accounts for 20 percent of cases. Blisters form on both the outer and inner layers of skin.
- Junctional epidermolysis bullosa (JEB) affects around 10 percent of EB patients. Blisters form where the outer and inner layers of skin meet.
Each type has several subtypes. So far, at least 27 different types have been identified.
A person with EB has extremely fragile skin that can be easily damaged at the slightest rub. A gentle bump or knock, or even clothing that touches or rubs against the skin, can cause blisters.
In very mild cases, symptoms may not appear until later in life. When blisters do occur, they may heal with no, or minimal, scarring.
Typical signs and symptoms depend on the type of EB. They may include:
- Blistering on the skin, scalp, and around the eyes and nose
- Tearing of the skin
- Skin that looks very thin
- Skin that falls off
- Alopecia, or hair loss
- Milia, or very small, white bumps on the skin, which, unlike blackheads or whiteheads do not have an opening on the surface of the skin
- Loss of fingernails, toenails, or both, or deformity of the nails
- Blisters or erosions of the eye
- Excessive sweating
If the mucous membranes are affected, this can cause:
- Difficulties with swallowing, if blistering occurs around the mouth and throat
- Voice hoarseness due to blistering in the throat
- Breathing problems because of blistering in the upper airway
- Painful urination resulting from blistering in the urinary tract.
Symptoms are usually present very early in life, often fairly soon after birth. In a rare subtype of EB known as Kindler syndrome, blisters form from the time of birth.
EB is caused by faulty genes, which may be inherited. If EB is inherited, a parent has the faulty genes and passes them onto their child.
For JEB to be passed on, both parents must have the faulty gene. For all other types, only one parent needs to have it.
In other cases, the fault may occur during the formation of the egg or sperm.
The mutation is thought to occur in the keratin or collagen gene.
Most cases are diagnosed in infancy. In rare cases, when symptoms are mild, diagnosis occurs later on in life.
Diagnostic tests may include a biopsy, in which a small sample of affected skin tissue is taken for analysis. This can show where the skin is separating, and what kind of EB the person has.
A microscope and reflected light can reveal whether any of the proteins needed for forming connecting tissues are missing.
A high-power electron microscope can detect structural defects in the skin.
Blood samples from the patient, and maybe the parents too, can be tested for genetic issues, and to see whether the condition is inherited from a parent.
Tests can be carried out from the 10th week of pregnancy. Amniocentesis involves removing and examining a small amount of the amniotic fluid that surrounds the fetus. Sampling the chorionic villus involves testing part of the outer membrane that surrounds the fetus.
There is no cure, and treatments will focus on relieving symptoms and preventing skin damage, infections, and other complications. Psychological and emotional support may be important.
The doctor may teach the patient or parent how to lance any large blisters correctly, using a needle. Skillful puncturing can enable fluid to drain out of a blister without increasing the risk of infection or damaging the skin below.
A topical antibiotic may also be prescribed. Wound dressings should not stick to the skin.
If a lesion does not heal properly, a skin graft may be necessary. Covering the wound with skin may help the healing process.
Repeated, severe blistering and scarring can cause fingers to fuse, and there may be abnormal shortening of muscle tissue, making everyday tasks hard for the patient. Surgery may be necessary.
Pain is a major symptom of EB. Some kind of pain control is usually needed.
If blistering in the esophagus makes eating difficult, the doctor may recommend surgery to widen the esophagus.
If a patient cannot swallow food, a gastrostomy tube may be necessary. A surgical opening is made into the stomach, and a feeding tube is passed through it.
To prevent blistering, the National Institutes of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) suggest:
People with EB develop blisters more easily than other people.
- Wearing clothing that does not rub or irritate, for example, simple cottons
- Using lubricants on the skin to reduce friction
- Keeping room temperatures cool to prevent overheating.
They also suggest putting sheepskin on hard surfaces and car seats and wearing mittens while sleeping to prevent scratching.
A person with EBS can prevent blisters to the feet by avoiding long walks. Those with DEB or JEB should be extremely careful to avoid scratches and knocks to the skin.
Blisters or pain in the mouth can be helped by avoiding spicy foods and food items that may cut and scratch, such as potato chips.
To pick up an infant with EB, it is better to place one hand under their buttocks and the other behind their back.
Care should be taken that eye glasses do not cause blistering around the nose and ears.
A number of serious complications are associated with EB:
- Blisters can lead to infection and open sores
- Skin cancer is more common. Patients with DEB have a higher chance of developing squamous cell carcinoma before the age of 35 years. This is an aggressive form of skin cancer.
- Deformities can occur, for example fusion of the fingers in people with DEB.
- Vision loss is possible, if the conjunctiva and other parts of the eye are affected.
- Malnutrition can happen, if the patient cannot swallow easily.
- Anemia may develop due to chronic inflammation and blood loss.
Some of the complications of EB, such as dehydration, infection, internal blisters, malnutrition can be fatal, especially in young infants.