ITGB4 and epidermolysis bullosa simplex: Indeed, EBS is the most heterogenic type of EB and has recently been proved to be caused by mutations in at least eight other genes besides KRT5, KRT14 and TGM5, which are: PLEC, PKP1, DSP, JUP, DST, EXPH5, ITGA6 and ITGB4 (Fine et al. 2014).