The study results obtained in vitro and on the NIH-III-nude strains of immunodeficient mice using the skin equivalents containing Ks and DFs isolated from RDEB patients and from healthy donors confirmed that the expression of the COL7A1 gene by both cell types involved in the organization of DEJs is required to form the optimally functioning AFs [139,140]. This evidence concerns the gene COL7A1 and recessive dystrophic epidermolysis bullosa.