Once familiar with the pathophysiology of EBA, its definition as a "chronic autoimmune subepidermal blistering disease of the skin and mucus membranes" encompasses a lot of what it's all about but getting your head around the terms involved in the pathophysiology can be frustrating and so a break down of the terms in that definition can hopefully go a long way in a short time in explaining what EBA actually is:

Chronic: Chronic means being long-lasting and recurrent. In relation to a disease such as EBA it means a condition that can't be cured or made to go away although it can certainly be in remission. The periods of remissions can be short, very long or even permanent and this is certainly the case amongst the various members of the group.

Autoimmune disease: Our body's immune system is a collection of mechanisms within the body that protect us against disease by identifying and killing those things in our body that are harmful to us. The immune system needs to distinguish those things in our body that harm us from our body's own healthy cells and tissues in order to function properly. When the immune system fails to separate and recognise the harmful things in our body from the non-harmful then it starts attacking its own healthy constituent parts. i.e. Those mechanisms within the body that are meant to protect the body end up attacking it instead. This is known as Autoimmunity and any disease, such as EBA, that results from autoimmunity is called an autoimmune disease.

Subepidermal blistering: As the diagram below shows, our skin is made up of 3 distinct layers: the epidermis, the dermis and the hypodermis (also known as the subcutaneous fat/layer). Of significance to understanding what EBA is, is knowledge of the fact that at the bottom of the epidermis is a very thin memberane, called the basement membrane, which attaches the epidermis to the layer below. Therefore subepidermal blistering is blistering that occurs below the epidermal layer.

Mucus membrane blistering: The mucus membrane is the thin skin lining all body cavities and canals that come into contact with the air. This therefore applies to the whole of the alimentary tract. So in summary, we can give a slightly more friendly definition of EBA:

In normal individuals there are "anchors" that connect the basement membrane to the dermis and prevent the layers from moving independently from one another (see the picture below). The main component of these anchoring fibrils is something called type VII Collagen and it is parts of this type VII Collagen that the immune system incorrectly attacks.