Because he's the only known person on the planet with a particular genetic sequence in his DNA that almost killed him.
And it took a liver transplant to save Leo at only five months old after he was diagnosed with an illness described by a top consultant as "an extremely, extremely rare condition".
Leo, now three, beat the odds to be born at all. He became a "rainbow baby" after his mum had a series of miscarriages and went through a failed IVF before further fertility treatment finally worked.
Now there's no stopping the plucky lad. His recovery was so remarkable he was able to take part in the British Transplant Games in 2022 as a tribute to his donor and their family.
So it's no wonder proud Claire, 43, married to musician Ollie, 38, says: "We tell him every day how amazing and special he is. We talk to him about his transplant. I'll say, Show mummy where they put the magic in, and he pulls up his top and rubs his tummy.
"And we can't thank his donor and their family enough. We think of them every day. Without them the baby we'd longed for would not be here."
Claire and Ollie met in 2012 and married in 2014. They soon started trying for a baby, but five pregnancies ended in unexplained miscarriages.
Finally, after failed private IVF in the UK, the couple flew to a Greek clinic recommended by a friend.
Denne historien er fra June 04, 2023-utgaven av The Sunday Mirror.
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Denne historien er fra June 04, 2023-utgaven av The Sunday Mirror.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
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