Epidermolysis bullosa is usually inherited. The disease gene may be passed on from one parent who has the disease (autosomal dominant inheritance). Or it may be passed on from both parents (autosomal recessive inheritance) or arise as a new mutation in the affected person that can be passed on.
The skin is made up of an outer layer (epidermis) and an underlying layer (dermis). The area where the layers meet is called the basement membrane. The various types of epidermolysis bullosa are largely defined by which layer the blisters form in.
The main types of epidermolysis bullosa are:
- Epidermolysis bullosa simplex. This is the most common form. It develops in the outer layer of skin and mainly affects the palms and the feet. The blisters usually heal without scarring.
- Junctional epidermolysis bullosa. This type may be severe, with blisters beginning in infancy. A baby with this condition may develop a hoarse-sounding cry from continual blistering and scarring of the vocal cords.
- Dystrophic epidermolysis bullosa. This type is related to a flaw in the gene that helps produce a type of collagen that provides strength to the pig-skinlike dermis layer of the skin. If this substance is missing or doesn't function, the layers of the skin won't join properly.