When her failing liver, heart, lungs and kidneys were all successfully replaced as a teenager she vowed to repay the medical world.
Allison, 32, of Cardiff, was diagnosed with cystic fibrosis as a baby. Her liver failed when she was 14 and it was two years before a donor was found.
By 18, her lungs and heart had to be transplanted.
But she made it to medical school.
In 2005 she suffered kidney failure, but dad David, 62, was a match.
She said: "If I've learned anything, it's don't fear death, fear the unlived life. I've had more than a second chance thanks to two people who died. I'm not throwing it away."