TGM2 and Autoimmunity: Autoimmune bullous diseases (AIBD) are a heterogeneous group of dermatoses associated with autoimmunity directed against desmosomal structural proteins (pemphigus diseases group) or against dermal–epidermal junction structural proteins, namely, pemphigoid diseases group and epidermolysis bullosa acquisita (EBA), or with autoimmunity to enzymes-epidermal/tissue transglutaminases (dermatitis herpetiformis), clinically characterized by blisters and erosions on the skin and/or mucous membranes (1).