Caitlin Leggett, 24, has been told she has just six months to live after being diagnosed with acute myeloid leukaemia - and the diagnosis has left her twin sister, Grace, devastated10:31, 10 Jun 2026A 24-year-old twin has told how she developed a rash that wouldn't go away - and now has only six months to live.‌Caitlin Leggett, from Cardiff, was diagnosed with acute myeloid leukaemia - an aggressive cancer of the white blood cells - in April 2025, with a persistent rash being the only sign that something was wrong.‌After chemotherapy and a stem cell transplant, she went into full remission by December. But Caitlin was dealt an unimaginable blow last month when doctors told her the cancer had returned, and she had just six months to live.‌Having discovered that options available to her in the UK were unlikely to be curative, she is now seeking treatment abroad, where treatment and associated costs could reach £500,000.Caitlin's twin sister Grace Leggett, who has quit her job as a complex care personal assistant in Bristol to move back home to be closer to her family, said watching Caitlin go through all of this while facing the prospect that she might lose her sister in six months was incredibly painful. She said: "We're only 24 - nobody expects this to happen... being twins as well, you're not supposed to have one twin not be there. We've gone through life together, and I don't want our story to end here.''‌Caitlin and Grace have always been very close, even sharing a student house together in Bristol. After graduating in July 2024, Caitlin had planned to join the Army, wanting to train as an intelligence officer. She had her requisite medical assessment booked for April 2025, but in March of that year she said she developed a rash that did not go away despite using generic creams from the pharmacy.Her GP eventually ordered blood tests, which were taken on April 3, 2025. She was diagnosed with acute myeloid leukaemia (AML) the very next day.According to the NHS, symptoms of AML can include looking pale, feeling tired or weak, breathlessness, unusual and frequent bruising or bleeding, and losing weight without trying to, but Caitlin said she experienced none of these - just the unusual rash, which can also be a sign of blood cancer.‌After learning that treatment would involve a stem cell transplant, replacing the destroyed cancerous cells with healthy stem cells from a donor, the twins' whole family was tested to see if any of them could be a match.According to blood cancer and blood disorder charity DKMS, more than 2,000 people each year in the UK need a blood stem cell transplant, but just 7% of the entire eligible population in the UK are registered as potential donors. Both Caitlin and her sister Grace had registered as stem cell donors "years and years ago'', and initially Grace was told that she would likely be a match for her sister. Their entire lives, they had believed that they were fraternal twins, meaning there was a high chance that her stem cells would be accepted by Caitlin's body and would aid her recovery. But, genetic testing in June 2025 revealed they were actually monozygotic twins, meaning they were identical. This discovery meant a setback for Caitlin's treatment,' as the body has to recognise stem cells as foreign in order for them to combat the cancerous cells.‌No other family members were a match, and while waiting to find an alternative donor from the register, Caitlin achieved remission in May 2025 after two months of chemotherapy. But it was only the beginning of an agonising few months of false dawns and repeated rounds of treatment.In August 2025, she was told that the cancer had returned to her skin - an abnormal relapse which, she said, was exacerbated by difficulties finding a suitable stem cell donor.‌A menin inhibitors clinical trial successfully eliminated the leukaemia in her skin, and a second transplant was planned for December that year - but just a few days before, it was confirmed the cancer had returned.She was still able to have the transplant, which took place in December 2025, but needed extra full-body radiotherapy beforehand. The treatment was deemed successful, and she was told she was in remission again in January 2026. Caitlin was then scheduled for monthly bone marrow monitoring for three months, to check that the cancer had not returned, which were set to decrease to quarterly tests from March 2026. After persuading her consultant to give her an extra check-up, they found that the leukaemia had come back.Initially, the blast count came back at 5.7%, just over remission, but then about a week later it went up to 37%. So it's quite fast-growing.'' From May 2026, Caitlin has taken part in another drug trial for Bleximenib and is waiting to see whether her body responds.‌Her doctors say there is another drug trial option in case it is not successful - but she has been advised that these treatments are not curative. She said she has been told that a second stem cell transplant cannot be performed in the UK, and doctors have predicted that her current treatment plan will help her survive for just six more months. She has now decided to pursue curative treatment abroad, and is considering specialised leukaemia treatment in America or CAR-T cell therapy, a type of immunotherapy, in China or Singapore. Either one will cost hundreds of thousands of pounds.Caitlin and Grace have set up a GoFundMe page titled Saving Caitlin to try and fundraise £500,000 to cover the cost of the expensive overseas treatment as well as transport, accommodation and sustenance for accompanying family members, and are appealing to anyone and everyone to help us in this fight''.Caitlin said: "At 24, I always assumed I had my whole life ahead of me. There are so many things I still want to do, places I want to see, and memories I want to make with the people I love.Article continues below"What I would miss most isn't one particular event, it's the chance to keep living an ordinary life with the people I love and growing older alongside my twin sister. Those are the things that matter most to me, and that's why I'm doing everything I can to find another treatment option.`I don't want to miss out on the future we always thought we'd share together.''