Pete McCleave first heard about stem cells during his sciences degree in the 1990s. “I knew about them, I just didn’t know what they could be used for,” he says. “It all sounded very pie in the sky.” It wasn’t until two decades later when McCleave was diagnosed with myeloma blood cancer that he came across stem cells again. This time, he needed them to save his life.

“I was told that really the only chance I have, the best chance I have in seeing beyond the seven years I was given [to live] was finding a stem cell donor match,” he explains. His doctor reassured him that it would be easy to find a match because of his white-European background. But almost eight years later, he is still searching.

“Although I don’t look it, my family come from south-east Asia, Macau,” he says. “I’ve got this mixture of Chinese, Portuguese, Irish and English [heritage], which just makes it much more difficult. But I’m just reflective of so many people from different communities who just can’t find that stem cell donor match,” he says.

Each year, four out of 10 people in the UK don’t find their match in the event they need a stem cell transplant. People who are not from white European backgrounds have a much harder time finding a match, and many die waiting. If you are from an ethnic minority background, you only have a 37% chance of finding a matching donor on the stem cell register, compared with 72% for those from white European backgrounds, according to blood cancer charity Anthony Nolan.

If you have mixed heritage, like McCleave, the chances are even slimmer.

Family usually cannot help either, as there is only about 30% chance of finding a match with a parent, and 25% with a sibling. If a match is found, the likelihood is that it will come from a non-relative donor, which relies on a stranger. And with only 3% of the UK population registered as donors, the odds are not in many people’s favour.

Lower availability of matches for people from ethnic minority backgrounds is, in part, because their human leukocyte antigens (HLA) types are less common, says Michael Gallagher, media officer at the blood cancer charity DKMS.

HLA molecules are on the surface of most cells in the body, and help the immune system differentiate between foreign bodies and tissues that belong to the body. When two people “match”, they will share enough of the same HLA type for a donation to be possible.

Even if the stem cell register were broadly representative of the UK population, people from minority ethnic backgrounds are more likely to struggle to find someone who shares enough of the same types to be fully matched because there is a greater level of genetic diversity in these populations.

Helen and Arun Kumar’s daughter Elsie, who has Down’s syndrome, was 18 months old when she was diagnosed with myeloid leukaemia. “As parents, you’re devastated. Cancer to you is just such a scary word,” Kumar says.

Doctors warned that if Elsie relapsed, there was not much they could do without a stem cell donor with an almost perfect match. Even then, it was risky and due to Elsie’s mixed heritage, they were told this was highly unlikely. “I remember we just collapsed on the bed in absolute tears and again, we thought that was it.”

Elsie did relapse, but luckily, a match was found in America. With a sceptical all-clear from consultants, her parents decided to press ahead. “Since then she’s just thrived, absolutely thrived … she’s a joy, just a really happy child,” Kumar says. “This person has saved our daughter’s life and given us a chance to be a family.”

In certain communities, the idea of donating is marred by a mistrust of medical professionals due to historical abuses. “For some people from African and Caribbean backgrounds, there is a history of people being misused and experimented on without their knowledge … so there’s a real, understandable fear and distrust,” Gallagher says.

Sabrina Jarrett, national development manager at the African Caribbean Leukaemia Trust (ACLT), says this ties into the myths and misconceptions, which the organisation tries to challenge through education and access to information. “People ask ‘will I contract anything by donating? Is it painful?’. These are all misconceptions.”

There may also be socioeconomic conditions that play into the availability of donors. “Finance is everything. And it really is until you don’t have health before you go to the doctors. You think about your kids, you think about your job, you think about what time you have and if you’ve got the means to get there,” Jarrett added.

McCleave launched the 10,000 Donors campaign in 2018 to get more people registered, and within five months, had surpassed the target. “We’re north of 110,000 people registered now and we’ve had 21 confirmed matches for patients, which is amazing,” he says. “I don’t really pin my hopes on finding that stem cell match for me, just because it’s very, very, very unlikely and that’s fine.”