A child has been given a new genetically modified skin that covers 80% of his body, in a series of lifesaving operations.
Hassan, who lives in Germany, has a genetic disease - junctional epidermolysis bullosa - that leaves his skin as fragile as a butterfly's wings.
A piece of his skin was taken, its DNA was repaired in the laboratory and the modified skin grafted back on.
After nearly two years, the new skin appears completely normal.
The family's full details have not been released to protect their privacy, but Hassan's father said the transformation was "like a dream".
"Hassan feels like a normal person now, he plays, he's being active, he's enjoying his life and he's not the way he was before," he said.
Hassan was born in Syria and has had blisters and wounds all over his body since he was a few days old.
Normally, the different layers of the skin are held together by "anchoring proteins".
But the junctional epidermolysis bullosa means Hassan's DNA lacks the instructions for sticking his epidermis (the surface layer) to the dermis (the next one down).
There is no cure, and about four in 10 patients do not even reach adolescence.
Hassan attended the Children's Hospital at Ruhr-University, in Bochum, Germany, in June 2015.
The seven-year-old was missing a massive amount of epidermis. Most of his body looked like a red-raw open wound.
Doctors were preparing the family for the worst.
Dr Tobias Hirsch, from the hospital, said: "We initially decided to provide palliative care because we had no chance to save the life of this child."
But a team of biologists specialising in gene therapy were brought in from the University of Modena and Reggio Emilia, in Italy - and the parents gave approval for them to try an experimental therapy.
So how did they save Hassan's life?
In September 2015, a 4 sq cm (0.6 sq inches) patch of skin was taken from an area where the epidermis was still intact.
The biopsy was then infected with a customised virus.
Viruses are good at getting inside cells, and this one was used like a postman to deliver the missing instructions for binding the layers of skin together.
The now genetically modified skin cells were grown to make skin grafts totalling 0.85 sq m (9 sq ft).
It took three operations over that winter to cover 80% of the child's body in the new skin.
Hassan's father said his son had spent months covered in so many bandages he had looked like a mummy.
But 21 months later, the skin is functioning normally with no sign of blistering.
You can even pinch the once incredibly fragile skin, with no sign of damage.
Dr Hirsch said: "The kid is now back to school, he plays soccer, so there was a tremendous increase in quality of life."
Dr Anna Martinez, who leads the national epidermolysis bullosa service at Great Ormond Street Hospital, told the BBC: "I got goosebumps when I heard this, it was just incredible.
"Today this treatment is not available and it is not going to be available in the next few months, but this is a massive advance in research and is going to give us hope going forward with gene therapy."
Epidermolysis bullosais is rare, but the charity DEBRA, which campaigns for EB patients, estimates half a million people are affected around the world.
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 Hassan's skin, detailed in the journal Nature, has discovered a group of long-lived stem cells are that constantly renewing his genetically modified skin.
Follow James on Twitter.