Definition
Epidermolysis Bullosa includes a group of heterogeneous dermal pathologies (genodermatoses), which are mainly hereditary, characterised in clinical terms by the fragility of the epithelium. This leads to the formation of blisters and (sometimes mucous) membranes as a result of the weakness of the connective tissue between the epidermis and the dermis. These blisters form in response to minor injury or physical touch. The blisters may be extremely painful and can appear anywhere on the body, including the internal mucous tissue.
The impact of the disease varies according to the type, ranging from minor functional impairment to severe disability and in some instances, death of the child.
The incidence of Epidermolysis Bullosa (including all forms) is circa 2 cases out of every 100,000 births.
Types of EB
Today, Epidermolysis Bullosa is classified according to the location of skin separation, though it was formerly determined according to clinical criteria.
With the benefit of histological, immunohistological and ultrastructural studies, it is possible to distinguish three groups within hereditary variants of EB according to the location of skin separation:
- Epidermolysis Bullosa Simplex is characterised by separation of the skin within the epidermis. This is the most frequently occurring type. (EBS)
- Junctional Epidermolysis Bullosa is the separation of the skin between the epidermis and dermis at the level of the basement membrane (JEB)
- Dystrophic Epidermolysis Bullosa describes a separation of the skin beneath the basement membrane within the dermis. (DEB)
There are various sub-types of EB within these groupings. They are defined according to the structural protein, phenotype and molecular biology. Variations may be inter or intra-familial.