Shirley Kordie, 33, has hypoplastic MDS and will leave her son, Blessing, four, without a mother if she is not treated soon.
Her brother Joseph, who lives in Ghana, is a “perfect” stem cell match but his visa application was denied due to his “financial circumstances”. The Home Office said it was “urgently reviewing” the case.
Ms Kordie said: “My life is in danger – I need to get my life back for my son.
“I have my little boy, and I want to live for him.”
The Anthony Nolan Trust and the African Caribbean Leukaemia Trust (ACLT) have launched a campaign to support Ms Kordie, who has been receiving treatment at Birmingham’s Queen Elizabeth Hospital.
The Anthony Nolan Trust said the reason Joseph had been refused a visa is because “he doesn’t earn enough money”. A petition urging the government to reverse its decision had amassed about 10,000 signatures in 36 hours.
Joseph, a nurse himself, is unable to make the donation in Ghana, so coming to the UK is his only option, said the Anthony Nolan Trust. Spokeswoman Amelia Chong said there were no alternative options for a donor on the international stem cell register.
“Her brother is a perfect, 10 out of 10 match for her,” she said. “We have reviewed all those on the donor list and he is not only the perfect match, he is the only match. “All Joseph needs is a temporary visa to undergo the procedure.”