All patients will have a blood sample of 5 ml on EDTA, 10 ml on heparin and 5 ml on dry tube collected for genomic DNA extraction to identify or verify COL7A1 mutations: mutation screening of the patients will be performed to identify COL7A1 mutations on both alleles. 2) HLA genotyping: patients selected on the clinical and molecular criteria will be HLA-genotyped by PCR to determine the likelihood of an immune response to the type VII collagen wild-type protein. A 5-mm punch skin biopsy performed under local anaesthesic will be undertaken during visit 1 for diagnostic purposes .The consequences of COL7A1 mutations on collagen VII protein expression will be determined, if not performed previously. Two additional 5-mm punch skin biopsies will be taken from different areas from up to 10 patients during the second visit. Keratinocytes and fibroblasts will be expanded and stored in vapor-phase liquid-nitrogen.