Is the cause of junctional EB known?

Yes. The most common cause of JEB is a defect in a protein at the DEJ called laminin 5. Laminin 5 is very important in keeping the epidermis attached to the dermis; therefore the split in JEB is at the lamina lucida within the DEJ. Many of the mutations in the laminin 5 gene that result in the lethal form of JEB cause a stop codon, which results in early termination of transcription; so, very little laminin 5 is made. In the milder forms of JEB, having a laminin 5 mutation, the result is just an abnormal or truncated protein that still maintains some function. There are other rarer forms of JEB that can result from mutations to the genes that encode for either bullous pemphigoid antigen-2 (also referred to as type XVII collagen) or a6b4 integrin. Both proteins are found in the anchoring filaments at the DEJ. Of note, the form of JEB involving a6b4 integrin results in pyloric atresia in addition to blistering.


Bauer JW, Lanschuetzer C: Type XVII collagen gene mutations in junctional epidermolysis bullosa and prospects for gene therapy, Clin Exp Dermatol 28:53–60, 2003.

Iacovacci S, Cicuzza S, Odorisio T, et al: Novel and recurrent mutations in the integrin beta 4 subunit gene causing lethal junctional epidermolysis bullosa with pyloric atresia, Exp Dermatol 12:925, 2003.