Many genetic diseases have a known treatment. Other rare disorders remain unknown and without cure or treatment, despite being severe, lifelong conditions.
One of these diseases is epidermolysis bullosa (also known as EB). This is a hereditary disease that is characterized by blistering of the skin.
Our skin has several layers: an outer layer known as the epidermis and a middle layer known as the dermis. The differences between these layers are not visible to the naked eye but using the right equipment one can see that these are two separate layers, attached with the help of proteins that maintain their form. In epidermolysis bullosa, these proteins are defected and cannot function properly.
When this adhesive layer is damaged, even the slightest injury can cause them to separate. This separation causes blisters and open sores that can become very painful.
Epidermolysis bullosa currently has no known cure.
Types of epidermolysis Bullosa
Epidermolysis Bullosa Simplex (EBS) – EBS is a dominant inherited disease – one defected gene from one of the parents is enough for the child to develop the disorder, regardless of the other parent’s genes. EBS is caused by a mutation in two KRT genes – number 14 and number 5.
In EBS, even the slightest touch can cause large blisters on the limbs due to a separation of the epidermis and dermis. These blisters do not usually cause any scarring and can pass with the right treatment.
Junctional Epidermolysis Bullosa (JEB) – This is one of the most severe forms of epidermolysis bullosa. The inheritance pattern is recessive, which means the child must inherit two defected genes (one from each parent) to develop the condition. The disease begins in early infancy. Fluid filled blisters can appear on the entire body because of touch. Some of these blisters are internal and appear in the digestive system. There are over ten types of JEB currently known to research.
Genetic screening tests
Genetic sequencing (sequencing panel)
Anyone can undergo genetic testing to detect mutations, but these tests are not always required. Research that mapped many families that are carriers of the EB mutation have concluded that when ethnic descent or family history indicate a risk of this disease genetic testing is required.
The tested genes belong to the COL7A1 and KRT groups. These genes are carefully tested to detect recessive carriers of the disease.
Skin biopsy
In pregnancies where both parents are carriers of the EB mutation, each fetus must be tested separately to determine whether the disease was inherited. Skin biopsies from the uterus can be performed in advanced stages of pregnancy, around weeks 18-20.
Monitored by ultrasound equipment, a needle is inserted into the uterus and a small sample of skin cells are extracted. These cells are then genetically tested in a lab to diagnose for EB.
PGD – Preimplantation genetic diagnosis
As is the case with other genetic disorder, preimplantation genetic diagnosis can be performed in cases of a risk of epidermolysis bullosa. During IVF (in vitro fertilization) cells are sampled and tested. Only fetuses that are found to be healthy are implanted in the uterus, this helps ensure a healthy pregnancy and avoid passing down the condition.
