Epidermolysis bullosa (EB) is a group of genetic skin diseases that cause the skin to blister and erode very easily. In people with EB, blisters form in response to minor injuries or friction, such as rubbing or scratching. There are four main types of EB, which are classified based on the depth, or level, of blister formation: Epidermolysis bullosa simplex Dystrophic Epidermolysis bullosa Junctional Epidermolysis bullosa Kindler Syndrome EB may then be further classified based on severity and specific symptoms, such as distribution (localized or generalized) and whether parts of the body other than the skin are affected. Specific sub-types may then be determined based on identifying the exact protein that is defective in a person with EB. This may be done by tests performed on a skin biopsy, or when possible, genetic testing. Identifying the exact sub-type can be hard because there are many sub-types of EB. A person with any main type of EB may be mildly or severely affected, and the disease can range from being a minor inconvenience requiring modifying activities, to completely disabling and even fatal in some cases. EB may be caused by changes in at least 18 genes that play various roles in the structure, integrity, and repair of the skin. Inheritance may be autosomal dominant or autosomal recessive depending on the type and subtype of EB a person has.