Types of EB

Recessive Dystrophic Epidermolysis Bullosa (RDEB)

Recessive Dystrophic Epidermolysis Bullosa is an incurable, often fatal skin blistering condition caused by a lack of collagen protein in the skin. This makes the skin incredibly fragile, leading to blistering or skin loss at the slightest friction or knock. It is progressive and incredibly painful.

The level within the skin layers at which the defect occurs, and therefore at which the shearing happens, is so deep that it is equivalent to a third degree burn and is incredibly painful.

External skin and internal skin are affected, leading to blistering in the mouth and oesophagus (food pipe) and on the surface of the eyes. For a sufferer, this means that eating is always painful.

Swallowing can be very difficult due to scarring of the oesophagus, necessitating balloon dilatation to allow food to pass. Many children and adults are fed via a gastrostomy tube to allow adequate nutrition.

The fragile skin around the anal sphincter is similarly affected, leading to fissures, intense pain and often constipation because of the pain associated with this everyday act. Laxatives and softeners are used on a daily basis in an attempt to combat this discomfort.

If the UV protective layer of the cornea is sheared off the eye is vulnerable to UV light. The intense pain that this causes leads to a sufferer closing their eyes, rendering them temporarily blind till healing occurs.

The progressive nature of RDEB leads to scarring and contractures. In real terms this means hugely reduced mobility, fusing of the fingers and toes causing mitten deformities, microstomia (small mouth opening) and therefore significant disability. Most sufferers are wheelchair reliant by their teenage years. Doctors begin to look for skin cancer in the late teens. After years of skin damage and pain, the majority of sufferers will succumb to a malignant skin cancer, Squamous Cell Carcinoma before the age of thirty five.

 

Aggressive and usually fatal skin cancers develop in areas of scarring and chronic wounds.

 

Junctional Epidermolysis Bullosa (JEB)

In this type, blistering occurs in a skin layer called the lamina lucida within the basement membrane zone, which is situated at the junction between the epidermis (upper layer of the skin) and the dermis (lower layer). JEB is a very severe type of EB and accounts for about 5 percent of cases.

Like EBS, JEB also is inherited in an autosomal recessive manner. However, the condition develops only when the defective gene is inherited from both parents who are EB carriers but do not show any symptoms themselves.

JEB exists in three forms: Herlitz JEB, a very severe form of EB that can cause serious blistering internally and externally, causing extensive damage to the respiratory system and is often deadly within early years of life; non-Herlitz JEB, where blistering may be mild or severe, but can cause life-long pain and be disabling; and JEB with associated pyloric atresia, a severe form that affects both the skin and digestive tract.

Epidermolysis Bullosa Simplex (EBS)

In this type, blistering occurs in the upper layer of the skin called the epidermis. It is characterized by a lack of adhesion of the skin directly above the basement membrane (the basal layer). EBS is the most common type of EB, accounting for 70 percent of cases. EBS is generally milder than other types of EB, although the blistering is painful and easily compounded by rubbing.EBS usually is inherited in an autosomal dominant manner, meaning that a defective gene inherited from a parent is enough to develop the condition. The blistering may develop either on hands or feet (localized EBS) or all over the body (generalized EBS).

Kindler Syndrome

Kindler syndrome is a rare type of EB that results from mutations in the FERMT1 gene. From early infancy, people with Kindler syndrome have skin blistering, particularly on the backs of the hands and the tops of the feet. Affected individuals also develop thin, papery skin starting on the hands and feet and later affecting other parts of the body. Kindler syndrome can also cause people to be highly sensitive to ultraviolet (UV ) rays from the sun and to sunburn easily.

Kindler syndrome can also affect the moist lining (mucosae) of the mouth, eyes, esophagus, intestines, genitals, and urinary system, causing these tissues to be very fragile and easily damaged. Affected individuals commonly develop severe gum disease that can lead to early tooth loss. The moist tissues that line the eyelids and the white part of the eyes (the conjunctiva) can become inflamed (conjunctivitis), and damage to the clear outer covering of the eye (the cornea) can affect vision. Narrowing (stenosis) of the esophagus, which is the tube that carries food from the mouth to the stomach, causes difficulty with swallowing that worsens over time. Kindler syndrome increases the risk of developing a form of cancer called squamous cell carcinoma.