Epidermolysis Bullosa Classification and Current Approach to Diagnosis

Epidermolysis bullosa (EB) is a heterogeneous group of rare genodermatoses marked by skin fragility and bullae formation induced by minor trauma. Pathologic variants in at least 21 genes are associated with EB, grouped into four major subtypes based predominantly on the plane of cleavage within the skin. EB simplex is characterized by epidermal bullae formation and is due to gene mutations that affect epidermal proteins, most commonly keratin filaments. Junctional EB is due to gene mutations affecting proteins in the basement membrane zone, causing a split within the lamina lucida of the dermal-epidermal junction. Dystrophic EB is characterized by subepidermal bullae formation and is due to mutations in the gene encoding type VII collagen, which makes up the anchoring fibrils in the papillary dermis. Kindler EB is the rarest subtype and may be associated with cleavage at various levels within the skin due to a mutation in the FERMT1 gene causing defects in kindlin-1, a protein associated with integrins and focal adhesions. Because EB is such a heterogeneous disease, an understanding of genotype-phenotype correlations is necessary to help guide management. Traditionally, the first step in diagnosis was inducing a blister that was biopsied for immunofluorescence mapping. Currently, the gold standard for diagnosis is a blood sample or buccal swab for extraction of genomic DNA via next-generation sequencing, which can identify the exact causative gene. A diagnosis of EB is life altering for patients and families alike. A firm understanding of EB classification and initial diagnostic workup can help dermatologists feel empowered to support and counsel families.