These included CXCL12/SDF1, the ligand for CXCR4, which directs cells of the bone marrow to damaged tissue including skin [34] and HMGB1, which has shown to be positively correlated with RDEB severity [35] and also mediates recruitment of bone marrow-derived cells to injured tissue [36]. This evidence concerns the gene CXCR4 and recessive dystrophic epidermolysis bullosa.