Basement membrane zone
Depending on the type of epidermolysis bullosa, blistering may occur in the top layer of skin (epidermis), the bottom layer (dermis) or the layer that separates the two (basement membrane zone).
Autosomal dominant inheritance pattern
In an autosomal dominant disorder, the altered gene is a dominant gene located on one of the nonsex chromosomes (autosomes). You need only one altered gene to be affected by this type of disorder. A person with an autosomal dominant disorder — in this case, the father — has a 50% chance of having an affected child with one altered gene (dominant gene) and a 50% chance of having an unaffected child with two typical genes (recessive genes).
Autosomal recessive inheritance pattern Open pop-up dialog box Close Autosomal recessive inheritance pattern Autosomal recessive inheritance pattern
To have an autosomal recessive disorder, you inherit two changed genes (mutations), one from each parent. These disorders are usually passed on by two carriers. Their health is rarely affected, but they have one changed gene (recessive gene) and one unaffected gene (dominant gene) for the condition. Two carriers have a 25% chance of having an unaffected child with two unaffected genes (left), a 50% chance of having an unaffected child who also is a carrier (middle), and a 25% chance of having an affected child with two recessive changed genes (right).
Epidermolysis bullosa simplex
Epidermolysis bullosa simplex usually becomes apparent at birth or during early infancy. It's the most common and least severe type. Blistering may be relatively mild with epidermolysis bullosa simplex.
Dystrophic epidermolysis bullosa
Dystrophic epidermolysis bullosa generally becomes apparent at birth or during early childhood. More severe forms of dystrophic epidermolysis bullosa can lead to rough, thickened skin, scarring, and disfigurement of the hands and feet.
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.