There are different forms of epidermolysis bullosa, including simplex, dystrophic and, as in this case, junctional.

Each is caused by different genetic faults leading to different building blocks of skin being missing.

Prof Michele De Luca, from the University of Modena and Reggio Emilia, told the BBC: "The gene is different, the protein is different and the outcome may be different [for each form of EB] so we need formal clinical trials."

But if they can make it work, it could be a therapy that lasts a lifetime.

An analysis of the structure of the skin of the first patient to get 80% of his replaced has discovered a group of long-lived stem cells are that constantly renewing his genetically modified skin.