Dystrophic epidermolysis bullosa is one of the major forms of a group of conditions called epidermolysis bullosa. Epidermolysis bullosa cause the skin to be very fragile and to blister easily. Blisters and skin erosions form in response to minor injury or friction, such as rubbing or scratching. The signs and symptoms of dystrophic epidermolysis bullosa vary widely among affected individuals. In mild cases, blistering may primarily affect the hands, feet, knees, and elbows. Severe cases of this condition involve widespread blistering that can lead to vision loss, scarring, and other serious medical problems.
Researchers classify dystrophic epidermolysis bullosa into major types based on the inheritance pattern and features of the condition. Although the types differ in severity, their features overlap significantly and they are caused by mutations in the same gene.
Recessive dystrophic epidermolysis bullosa severe generalized (RDEB-sev gen) is the classic form of the condition and is the most severe. Affected infants are typically born with widespread blistering and areas of missing skin, often caused by trauma that occurs during birth. Most often, blisters are present over the whole body and affect mucous membranes such as the moist lining of the mouth and digestive tract. As the blisters heal, they result in severe scarring. Scarring in the mouth and esophagus can make it difficult to chew and swallow food, leading to chronic malnutrition and slow growth. Additional complications of ongoing scarring can include fusion of the skin between the fingers and toes, loss of fingernails and toenails, joint deformities (contractures) that restrict movement, and eye inflammation leading to vision loss. Additionally, people with RDEB-sev gen have a very high risk of developing a form of skin cancer called squamous cell carcinoma in young adulthood. In these individuals, the cancer tends to be unusually aggressive and is often life-threatening.
Other types of recessive dystrophic epidermolysis bullosa fall along a spectrum referred to as RDEB-generalized and localized (RDEB-gen and -loc). These forms of the condition are somewhat less severe than RDEB-sev gen and are distinguished by the affected regions of the body. Blistering is often limited to the hands, feet, knees, and elbows in mild cases, but may be widespread in more severe cases. Rare forms affect specific regions of the body, such as the shins or the abdomen. Affected people often have malformed fingernails and toenails. The RDEB-gen and -loc types involve scarring in the areas where blisters occur, but these forms of the condition do not cause the severe scarring characteristic of RDEB-sev gen.
Another major type of this condition is known as dominant dystrophic epidermolysis bullosa (DDEB). The signs and symptoms of this condition tend to be milder than those of the recessive forms, with blistering often limited to the hands, feet, knees, and elbows. The blisters heal with scarring, but it is less severe than in recessive forms of this condition. Most affected people have malformed fingernails and toenails, and the nails may be lost over time. In the mildest cases, abnormal nails are the only sign of the condition.