A Case Study of Epidermolysis Bullosa
By: Laurie S. Longe
EB is a disorder in which painful blistering affects the skin. Non-scarring
forms may depend on the weather or temperature, and often appear on the
hands and feet. The scarring varieties consist of open sores and blisters
which can lead to disfigured, or mittened hands and feet, scar tissue in
the mouth, or infection in the digestive organs.
The Simplex form of EB is inherited as an autosomal dominant trait, while
both the Dystrophic illness and the Basement Membrane disorder are recessive
forms of the mutation. In EB Simplex, a mutation in a gene on chromosome
number five, which encodes keratin, is affected. In the Dystrophic illness,
the gene encoding collagen is affected. This results in difficulties in
connecting the dermis and epidermis. In the Basement Membrane disorder,
anchoring of the epidermis to the basement membrane by the protein epiligrin
is affected. Although all three types of EB discussed above have different
causes, their symptoms are similar; the diseases manifest themselves in
painful blisters and sores. Both the Dystrophic type and the Basement Membrane
disorder deal with anchoring of the skin layers due to lack of a specific
protein. Though the EB illnesses vary in genotype, the phenotype is similar.
In each case, a lack of proteins in the skin yield mutation. Perhaps it
is due to the lack of vital proteins in the skin layers which lead to the
intense blistering of the skin.
Because EB Simplex is a dominant trait, a parent with the affected gene
has a fifty percent chance of having a child with EB, regardless of sex
or birth order. In the recessive traits of EB, the child needs to inherit
an EB recessive gene from each parent in order to have the disease, (fifty
percent.) A child who inherits only one gene for recessive EB will be a
carrier for EB, (twenty-five percent.) The chance of EB carrier parents
having a normal child who is not an EB carrier is twenty-five percent. (This
is also regardless of sex or birth order.)
One in fifty thousand infants is born with EB. Gene therapy is a possibility
for EB patients who have the Simplex form of the virus. Keratinocytes can
grow in culture, accept foreign genes, and be grafted onto a person. This
is beneficial to EB Simplex patients because the mutation occurs in the
epidermis. In the Dystrophic and Basement Membrane forms of EB, tissue beneath
the epidermis is affected. In the Dystrophic form, the fibers anchoring
the dermis to the epidermis are affected. Due to the fact that connective
tissue and proteins beneath the epidermis are damaged, the act of simply
grafting them onto a person would not be affective for patients diagnosed
with these two types of EB.
Treatment for EB consists of minimizing infection due to open sores and
blisters, and replacement of lost fluid. Specially cushioned shoes should
be worn to minimize foot pain. Scar tissue may be surgically removed in
some cases. Pertaining to the Dystrophic illness, current research indicates
that EB patients manufacture high levels of collagenases. Injections of
collagen have led to decreased blistering in some cases. However, there
is no cure as of yet for EB. Many EB patients develop cancer, malnutrition,
and infections due to oral scar tissue and sores in the digestive system.
1.) Gedde-Dahl, T. Epidermolysis Bullosa: A Clinical, Genetic, and Epidemiological
Study. The John's Hopkins Press, MD; 1971.
2.) Lin, A. and Carter, D. Epidermolysis Bullosa: Basic and Clinical Aspects.
Springer-Verlag, NY; 1992.
3.) Priestley et. al. Epidermolysis Bullosa: A Comprehensive Review of
Classification, management, and Laboratory Studies.
DEBRA, Crowthorne, UK; 1990.
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