Dystrophic EB can be either dominantly or recessively inherited and involves defects in Type VII collagen. Blisters occur within the lower layer of skin, the dermis. There are two main subtypes, dominant DEB (DDEB) and recessive DEB (RDEB).
Recessive Dystrophic Epidermolysis Bullosa is an incurable, often fatal skin blistering condition caused by a lack of collagen VII from birth. This makes the skin incredibly fragile, leading to blistering or skin loss at the slightest friction or knock. Sometimes these wounds can persist for years.
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 (mucous membranes) 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. A small mouth opening (microstomia) and tongue scarring and contracture further make eating difficult. Many children and adults are fed via a gastronomy 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 current standard of care is limited to management of the condition. EB blisters are not self-limiting and get bigger until the skin roof shears off, so blisters need to be pricked with a hypodermic needle and flattened. Wounds and body parts are covered extensively with special non-stick bandages which can cost thousands of pounds per month. Dressing changes can take between four and five hours per day and take a terrible toll on the sufferer as they are always painful.
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 (pseudosyndactyly), small mouth opening (microstomia), 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.
Dominant Dystrophic Epidermolysis Bullosa is usually mild. Blistering may be localised to the hands, feet, elbows and knees; or it may be generalised. Common findings include milia (tiny white bumps), mucous membrane (internal skin) involvement, and abnormal or absent nails. Some family members may only have nail dystrophy.