What's Up Doc? Rare skin disorder causes blistering, calls for genetic counseling

Q:  What is epidermolysis bullosa?

A: Epidermolysis bullosa is a group of rare skin disorders that cause fragile, blistering skin.

There are four major subtypes of EB and more than 30 different subtypes. The types/subtypes of EB differ in the specific ways they are inherited and the symptoms and complications they cause.

EB has been diagnosed in up to 20 per million live births, although the milder forms may go undiagnosed or may not be diagnosed until adulthood, so the overall prevalence of this disease in the population is higher than this.

Dr. Jeff Hersh
Dr. Jeff Hersh

To understand this disease, it is important to understand the structure of our skin:

  • The skin is made up of two major layers; the epidermis, which is the outer layer of the skin, and the dermis, which is the deeper underlying layer.

  • The epidermis is the waterproof protective covering of the body.  The epidermis itself has sub-layers, which range from the very top layer of dead skin cells (the ones a loofah sponge scrapes off) down to the junction where it anchors into the dermis.  The dermis is the cushiony layer of the skin that contains the hair follicles, oil glands, sweat glands, blood vessels and nerves.  Under the dermis lies the subcutaneous tissues where fat, connective tissue, larger nerves and blood vessels all reside.

EB affects the anchoring of the epidermis to the dermis. When the anchoring mechanism fails these skin layers slip easily one over the other, making the skin very fragile. Blisters and sores caused by the friction from this slippage are the major symptoms. You can think of this as if the skin is receiving a hot water scald burn. You can imagine the problems that can arise from getting skin "burns" from even minor rubbing or pressure.

The blisters of EB may appear in response to minor injury, even from heat, rubbing, scratching or adhesive tape. The symptoms of the various types of EB can vary from fairly minor to very severe, even within some of the subtypes of this disease.

For those with very minor symptoms, the diagnosis may not be made until they are adults, even after age 50. Of the four major types, EB simplex is most common type, accounting for around 90% of all cases. In its mildest form the blisters usually occur only on the hands and feet of a newborn. Later in life, the skin may stop blistering, leaving a teen or adult with thickened, hard skin on the palms and soles. For those with severe symptoms this disease can disfiguring (for example, affecting the fingers and causing the patient to lose normal function of their hands) and can sometimes be life threatening, even during infancy.

In severe cases of certain types of EB the blisters may occur inside the body, such as the lining of the mouth or the stomach; this can cause nutritional problems as well as other complications. The respiratory system, the eyes and/or the teeth are affected in some subtypes of EB.

The diagnosis of EB is suspected clinically from the blisters that arise from even minor trauma, and is verified by doing special tests on a biopsy specimen taken from the patient’s skin and possibly from certain genetic tests.

Since this is an inherited disorder, families with a history of EB should get genetic counseling. Recommendations for prenatal screening (or pre-implantation for those having in vitro fertilization), which is available for many sub-types of this disorder, may be made.

Other complications of EB may include infections from the skin blisters, malnutrition (in those with GI tract involvement), fusion of fingers and/or joint changes (from severe blistering), as well as complications in other organ systems when these are involved.

The treatments for this disease are aimed at minimizing the complications and symptoms the disease can cause. This includes meticulous skin care - for example, wearing soft clothing, and using moisturizing lotions - aggressive wound management to minimize or prevent infections, attention to proper and adequate nutrition, as well as other treatments depending on the specifics of the organ involvement for the particular patient. Patients with tooth involvement should see a dentist with experience treating people with this disorder.

There is active research being done to improve the outlook for people with EB, including those with severe disease. This includes research looking at different treatments for different subtypes of disease, including using stem cells to promote healing, topically applying gene therapy viral vectors (as well as other gene therapy strategies), treatment with certain medications (e.g. the antibiotic gentamycin), others.

Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com

This article originally appeared on MetroWest Daily News: Epidermolysis bullosa is a group of rare skin disorders