Cardiff Woman Seeks £500,000 for Leukaemia Care Abroad After 6-Month Prognosis

Q: How did a DNA test meant to find a life-saving donor instead reveal a heartbreaking genetic obstacle for Caitlin and her twin?

The donor test revealed that Grace was not just a close match for Caitlin — she was effectively too close. While doctors were assessing Grace as a possible stem cell donor, DNA markers showed the sisters were actually identical twins, not fraternal as they had always believed. That discovery created the obstacle. In acute myeloid leukaemia, a transplant works best when donor cells are genetically matched enough to engraft but still foreign enough to mount a graft-versus-leukaemia effect, helping destroy remaining cancer cells. Because Caitlin and Grace share near-identical DNA, Grace could not provide that needed immune difference. The identical-twin finding also raised concern that the same genetic background could include shared predisposition or even pre-leukaemic changes, making Grace an unsuitable donor despite being Caitlin’s twin. In practical terms, the test that was supposed to identify a life-saving family donor instead ruled Grace out. So the heartbreak was twofold: the sisters learned unexpectedly that they were identical twins, and at the same moment learned that this bond meant Grace could not be the stem cell donor Caitlin needed.

3 articles · Updated · BBC.com · Jun 9

Caitlin Leggett, 24, is fundraising for potentially curative treatment in the US, China or Singapore after doctors told her relapsed acute myeloid leukaemia is unlikely to be cured in the UK.
An extra bone marrow test in May detected the latest relapse after a stem cell transplant and repeated remissions, prompting doctors to estimate her current treatment plan may extend survival by only six months.
Leggett first entered remission after chemotherapy in May 2025, relapsed twice, joined drug trials including menin inhibitors and Bleximenib, and was told a second stem cell transplant cannot be performed in the UK.
Her identical twin Grace could not donate stem cells because their DNA was too similar, a setback that emerged only after doctors confirmed the sisters were identical rather than fraternal twins.
The appeal also highlights a wider donor shortage: more than 2,000 people in the UK need a blood stem cell transplant each year, while only 7% of eligible people are registered as potential donors.

Sources

BBC.com4h ago

Cardiff Woman Caitlin Leggett, 24, Seeks £500,000 for Leukaemia Treatment Abroad After Relapse

Facebook4h ago

A 24-year-old twin given six months to live after her leukaemia returned is raising £500,000 for potentially curative treatment overseas, saying the thought of leaving her identical sister alone is “unthinkable”. Caitlin

Wales Online4h ago

Cardiff woman, 24, with six months to live says leaving twin 'unthinkable' | Wales Online

6 Sources

Can experimental CAR-T therapy abroad succeed where a stem cell transplant and UK clinical trials have already failed this patient?

Why must a young cancer patient crowdfund £500,000 for treatments that are unavailable through the UK's national health service?

How did a DNA test meant to find a life-saving donor instead reveal a heartbreaking genetic obstacle for Caitlin and her twin?

Caitlin Leggett’s £500,000 Appeal: The Urgent Fight for Life-Saving Cancer Treatment Abroad and the Systemic Gaps in UK Care

Overview

Caitlin Leggett, diagnosed with acute myeloid leukaemia in April 2025, achieved remission after chemotherapy and a stem cell transplant, but her cancer returned in May 2026. With UK treatments unable to offer a cure, Caitlin urgently needs advanced therapy abroad, prompting her family to launch a £500,000 fundraising campaign. This situation highlights the financial and emotional burdens families face when seeking overseas care, as well as the wider issue of unequal access to life-saving treatments. Caitlin’s story also underscores the importance of stem cell donor registration and the need for greater support and diversity in donor pools.

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