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Epidermolysis bullosa dystrophica, autosomal dominant (DDEB) and autosomal recessive (RDEB) - Inherited epidermolysis bullosa (EB) is a clinically and genetically heterogeneous group of mechanobullous disorders characterized by fragility of the skin with recurrent blister formation. EB can be divided into 4 major types: EB simplex (EBS), junctional EB (JEB), dystrophic EB (DEB) and Kindler syndrome. Dystrophic EB is distinguished by blisters that form below the lamina densa of the basement membrane within the upper dermis. The blisters affect both the skin and the mucous membranes and heal with milia formation and scarring.  Additionally, nail dystrophy is a common feature of DEB.  Patients with autosomal dominant DEB (DDEB; MIM 131750) usually have dystrophic nails and mild blistering of the hands, feet, knees, and elbows; however, in some cases dystrophic nails are the only clinical feature.  Autosomal recessive DEB (RDEB; MIM 226600) tends to be more severe with widespread blistering and in the worst cases scarring that can result in fusion of the fingers and toes and erosion of the oral cavity, esophagus, and cornea. Both DDEB and RDEB are caused by mutations in COL7A1. DDEB is generally due to glycine substitutions within the triple helical domain of COL7A1, while RDEB is primarily caused by loss-of-function mutations in COL7A1.