EB is a rare, genetic skin disease that involves the connective tissues of your skin. Even the slightest bit of friction to the skin can cause severe blistering, both inside and outside of the body. Individuals with EB are usually refered to as "Butterfly Children" because their skin is as fragile as the wings of a butterfly. There is currently no cure for EB, and the only treatment is supportive care such as wound care and bandaging (or in Tripp's case: wound care, bandaging, eyes, trach, feeding tube, etc...) Severe forms of EB often lead to constant pain and scarring; or in some cases death. I like to use the analogy that I got from the dermotologist in Cinncinati- In EB, the top layer of skin is the grass, and the bottom layer is the soil- but you are missing the "roots" that hold the skin together.
In most cases, EB is inherited. Research has found that there are close to 10 genes involved with the skin formation that can be mutated and cause EB. But in addition to EB being inherited, it can also be caused by a spontaneous mutation.
There are 3 main types of EB: Simplex, Junctional, and Dystrophic.
In simplex, most cases are inherited by a dominent gene mutation (one parent carries the mutation).
Junctional EB, can ONLY be inherited by 2 recessive mutations from each parent, which is what happened in Tripp’s case. Tripp's dad and I both carried the recessive gene mutation.
Dystrophic EB can be inherited by either dominent OR recessive mutations.
Tripp has Junctional EB. We were told he is 1 in 2 million. His type is divided into 2 subtypes: Herlitz and non-Herlitz. Tripp’s biopsies to further diagnose him were inconclusive, and we never went any further. There have been both Herlitz and non-Herlitz babies that have not made it. What was the point in further testing? But the doctors are CERTAIN he is Herlitz (which is the most severe type with a life expectancy under 2 years). The doctors are amazed that Tripp is still alive.
First, I want to explain the “layers of skin” to you- in very “laymen” terms. I’ll describe them as if they were a flowerbed. There are 3 layers of your skin. Epidermis, Dermis, and Subcutaneous.
-Epidermis (mulch over a flowerbed): this layer is the very top thin layer that protects you from injury and organisms. It holds in fluid and protects your raw nerves from too much stimulation.
-Dermis (the top soil): this is where things grow. Hair follicles, sweat glands, nerve cells. If this layer gets damaged, it will drain a serous (clear) fluid and start to swell.
-Subcutaneous (the sandy foundation) this layer is not really skin, but attatches everything to the very bottom. The blood vessels in this layer feed the dermis (above it). (Insert Picture)
So now, there are 3 main types of inherited EB- Simplex, Junctional, and Dystrophic.
EB Simplex is most often dominantly inherited. It involves the uppermost layer of skin (within the epidermis) There is little internal involvement of blisters, except in the mouth- usually at a young age. The blisters usually affect the palms and soles of the hand and feet. And they often develop thickened fingernails shortly after birth.
Junctional EB is always recessively inherited. It involves the layers between the epidermis and dermis- depending on the different types. There are 2 main subtypes of Junctional EB: Herlitz and non-Herlitz.
-Junctional Herlitz is a very severe type of EB. Death usually occurs by the second year of life- do to infection, malnutrition, dehydration, electrolyte imbalance, organ failure due to internal blistering, etc. Blistering may be present at birth, but most times the blisters come gradually and usually affect every part of the body, including the mucous membranes.
-In non-Herlitz Junctional EB, blistering may be mild to severe, and also involve all the parts of the body, including the insides. Death may or may not occur from the same complications listed above.
Dystrophic EB can be inherited either by either a dominant or recessive gene. Blistering can be involved in the subcutaneous layer of skin or between the epidermis and dermis layers. And these blisters most time result in scarring and webbing of the hands and feet. There are two main types of Dystrophic EB: Dominant Dystrophic (DDEB) and Recessive Dystrophic (RDED).
-In Dominant Dystrophic, the blisters are usually limited to the hands, feet, knees, and elbows. However it can involve mucous membrane involvment and abnormal or absent fingernails.
-Recessive Dystrophic EB is typically more severe than DDEB, and in addition to what is listed above, there is also malnutrition, dehydration, webbing and fusing of the fingers and toes, internal organ involvement, esophogeal strictures, etc. The risk of skin cancer is increased for this type of EB and can sometimes result in death.
The genetics of EB are WAY over my head. But I will try to give a basic summary. There are three ways you can get EB: Autosomal Dominant Inheritance, Autosomal Recessive Inheritance, or a spontaneous mutation.
Autosomal Dominant Inheritance: this is where each gene for the condition expresses itself in an individual. A parent with an autosomal dominant form of EB has a 50/50 chance with each pregnancy of transmitting the abnormal gene. A child who does not inherit the gene for EB from that affected parent will not have the condition and cannot pass it on to future generations.
Autosomal Recessive Inheritance: this is where a recessive gene for the disorder is passed from each parent and the two genes are paired together, causing the disorder to be passed along to the child. If a person has one recessive EB gene paired with a normal gene, the person is “a carrier", but does not have the disorder. If parents are each both carriers of an autosomal recessive gene, there is a 25 percent chance with each pregnancy that their children will have the disorder. A person with a recessive form of EB will be at risk of having an affected child only if he or she reproduces with a carrier or another person with the recessive form of EB.
Spontaneous Mutation: In some cases, neither parent has EB, but the couple has a child with an autosomal dominant form of EB. In this situation, the condition has usually been caused by a change, or mutation in the genetic material of the egg or the sperm. When a new mutation occurs, the affected individual will have a 50/50 risk of passing the mutation on in future pregnancies, but his/her parents will not.
There are an estimated 1 in every 50,000 people in the U.S. that are born with some type of EB.
Tripp’s type- Junctional, is estimated at about 1 in every 2 million people.
Since EB is a genetic disease there is currently no cure for EB.
If you want more information, you can visit DebRA.org.
