Saved by a stranger... despite odds of 25 million to one: Joy of leukaemia patient, 24, as donor is found after worldwide search 

The chances of her finding a stem cell match for her aggressive form of leukaemia were heartbreakingly small.

With a Thai mother and an Italian father, Lara Casalotti, 24, had only a one in 25 million possibility of finding a donor.

But she refused to be disheartened and started a global search backed by everyone from JK Rowling and Stephen Fry to David Cameron.

Incredibly, a match has now been found and the person will donate their stem cells next month.

And, following the campaign, an estimated extra 20,000 people have joined registers so others looking for donors can be helped too.

With a Thai mother and an Italian father, Lara Casalotti, 24, had only a one in 25 million possibility of finding a donor but incredibly, after her high profile appeal, a match has now been found

‘These past months have been a whirlwind but I am so thankful a donor with a genetic match has now been found,’ she said.

‘Thanks to everyone's immense support, I have always stayed hopeful that I would find one, but I realise how lucky I have been given how difficult it was to find that donor.

‘I want to keep urging people to sign up to the donor registries so that everyone can have a chance of finding their match.’

Miss Casalotti, from Hampstead, north London, was diagnosed with acute myeloid leukaemia in December during a trip to Thailand and was told her best hope of a cure was a stem cell transplant.

But the student, who is enrolled on a masters course in global migration at University College London, faced a ‘needle in a haystack’ search due to her heritage.

Just three per cent of worldwide stem cell donor registers have mixed race donors. None of her family members were a match.

Her search was made more difficult because she was most likely to get a match from someone of a similar background and hers was a rare occurrence.

Now, after a global search by blood cancer charity Anthony Nolan - which included Thailand, the US and Italy - a match has been found.

The donor's identity has to be kept a secret due to patient-donor confidentiality regulations but it is hoped that they will donate their stem cells in March.

Miss Casalotti made the happy announcement on YouTube and will undergo the transplant next month

Miss Casalotti started a global search backed by everyone from JK Rowling to David Cameron after her diagnosis with an aggressive form of leukaemia

Miss Casalotti, pictured in hospital with her brother Seb who wasn't a match, and over Christmas (right)

Miss Casalotti’s mother, Supanya, said: ‘As a mum, I feel pure relief as we knew the odds were stacked against Lara.

‘Whoever the donor is, they will never, ever know how grateful I am. 

'The transplant is still a few weeks away and I wish I could wrap them in cotton wool to keep them safe.

‘We know we have a long road ahead as a transplant is an extremely serious procedure, but knowing there is a good match for Lara is a weight off our shoulders that we desperately needed.’

Her brother, Seb, 20, said: ‘We've been so lucky in finding a match but we know that others are not so fortunate.

‘The Match4Lara events planned around the world over the coming weeks will go ahead as planned, so that other families can one day receive the same good news.

‘This campaign was hatched around the dinner table and we never expected it to receive such incredible support - we were inspired by the Match4Aary campaign, who is still waiting for a match, so we need people to keep signing up to registries worldwide.’

Miss Casalotti’s family estimates that the number of people worldwide who have joined a stem cell register as a result is well in excess of 20,000 - a spike of 400 per cent.

Her recruitment drive has gone to various universities, including the University of East London where her father Dr Stefano Casalotti is a senior lecturer.

Miss Casalotti gives a thumbs up with her brother Seb, mother Supanya and father Stefano Casalotti. She revealed today that a match has been found after her campaign caused 20,000 to join the stem cell register

Anthony Nolan also saw an unprecedented spike in new donors from black, Asian, ethnic minority and mixed race backgrounds in the UK.

Ann O'Leary, head of register development at Anthony Nolan, said: ‘We're over the moon that we've been able to find a suitable donor for Lara and that she's now able to begin her transplant journey.

‘We're so grateful to Lara and all of her incredible supporters for spreading the word about the simple but vital act of donating stem cells. By diversifying the donor register, they have given hope to so many other people from ethnic minority and mixed race communities.’

If you're 16-30, you can join the Anthony Nolan register at the charity's website here.