The cause of the rare inversa type of the heritable blistering disorder recessive dystrophic epidermolysis bullosa (RDEB-I) is largely unknown. In RDEB-I, patients mainly have blisters in the body flexures and trunk, as well as the mucosal membranes. To increase our knowledge about RDEB-I, we collected a series of 20 patients from the Netherlands and UK and studied their skin and mucosal problems, and the relation of these problems with the genetic cause, mutations in the COL7A1 gene. We found that patients with RDEB-I have relatively mild skin problems. However, the mucosal problems can be very severe and debilitating, with some patients needing frequent oesophagus dilatations. We also found that RDEB-I is caused by two types of mutations in COL7A1: either the substitution of a specific arginine or glycine amino acid. We do not currently understand why these specific mutations lead to RDEB-I, but we suspect an important role for the higher temperature of the skin and mucosa where the blisters occur. (By Dr. Peter van den Akker, http://jmg.bmj.com/content/early/2010/11/26/jmg.2010.082230.abstract?papetoc )