Isabella Mannella was diagnosed in October and has big dreams of one day becoming a doctor.
Christina Petrovic is member of Isabella's family and said the odds are against the girl but there may be hope.
"She has a rare form of ALL (acute lymphoblastic leukemia) called precursor B and within that rare form a more rare form with a chromosomal abnormality that accounts for less than 1 per cent of the rarest forms of leukemia," she said.
The Canadian Blood Services' OneMatch Stem Cell and Bone Marrow Network is helping organize a swab event on Sunday in Vaughan in hopes of finding a match.
Experts says siblings work as a match 25 per cent of the time.
"That means 75 per cent of time patients would rely on someone they do not know, a stranger," said Hailu Mulatu with OneMatch.
Mulatu said simply swabbing a persons cheek can determine if they have the right genetic material to be a donor.
The Mannella family may have already found a match through a blood bank overseas, but there are no guarantees.
The event, which is also a fundraiser to help pay for Isabella's medicine, starts at 1 p.m. at the Springhill Marriott Suites in Vaughan.