A cancer patient from Monmouthshire received a lifesaving transplant from his own brother living in the United States after a global search for a stem cell donor.
And now the two are urging others to sign up to save lives.
Dr Nicholas Vaughan, from Monmouthshire, is sharing his story to raise awareness of the Welsh Blood Service's stem cell registry.
Dr Vaughan, a consultant radiologist at Velindre Cancer Centre and University Hospital Wales, first noticed something was wrong in April 2024 when a persistent cough wouldn't go away.
A routine blood test led to a diagnosis of leukaemia the following day.
After several rounds of chemotherapy, doctors began an urgent search for a stem cell donor, and a perfect match was found in the US.
Remarkably, the match was his brother, Matthew Vaughan, who had signed up to a US stem cell registry years earlier and had moved to Maryland in 2015.
Dr Vaughan said: "It's rather good to be alive, and miraculous that all my blood cells now come from Matt.
"When my marrow was in a mess, I needed transfusions to stay alive, but now it's all being made inside -- talk about a gift that keeps on giving.
"I wouldn't be here without him, but I do blame him for my grumpiness.
"After the transplant, it was slow going for many months but then became exciting to feel a bit stronger week by week.
"I'm now back at work, jogging, mountaineering, supporting the kids' sailing events, and spending time with friends and family."
Stem cell transplants work by replacing a patient's cancerous cells with healthy donor cells.
However, only around 25 per cent of patients find a match within their family, leaving most reliant on unrelated donors.
Matthew said: "When I donated to my brother last year, it felt surreal.
"I'd signed up casually to a US stem cell registry years before, and it turned out to be one of the most important things I've ever done.
"The support I received from the healthcare teams in the US and Wales was extraordinary, especially given the international logistics.
"While the spotlight is often on the donor and recipient, the network of medical professionals, friends, and family around us was absolutely vital.
"My message is simple: get registered.
"It takes so little time, but it can mean everything."
Despite more than 40 million stem cell donors registered worldwide, three in ten patients still do not find a match.
For patients from black, Asian, mixed, or minority ethnic backgrounds, the figure rises to seven in ten.
Christopher Harvey, head of the Welsh Blood Service's stem cell registry, said: "Blood cancer patients face a daily and urgent search for a suitable stem cell match.
"The requirements are very specific, but every new volunteer increases the chance of a lifesaving match."