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An international mission has been mounted to help a baby in Auckland with a blood type so rare only three frozen samples of it are known in the world.
The Herald understands a unit of cryogenically frozen red blood cells was flown to New Zealand before the the 1-year-old had an operation in the Starship hospital.
Other blood components came from Australia.
It is understood an elderly person with the same blood type was identified through the international registry of rare-blood donors, but when the donor could not be reached a 2-year-old frozen sample was used.
The NZ Blood Service's medical director, Dr Peter Flanagan, confirmed that frozen red blood cells were brought from overseas for the child's surgery.
He said New Zealand was able to meet most requirements for blood from its own donors.
"By the time you need to resort to international donor registries for blood, you're dealing with something which is very, very unusual."
The service could find only three frozen units in blood banks around the world.
The blood type is so rare that Dr Flanagan believes no one has done calculations as to its occurrence per million people.
"These are the kind of things that you occasionally find in the small print of textbooks.
"This particular group I've not come across in the many years I've been involved in transfusions. It is a very rare group."
Blood typing is most commonly associated with the ABO grouping system (A, B, AB, O) and the Rhesus factor (positive or negative), but the International Society of Blood Transfusion recognises 29 blood group systems.
Dr Flanagan said New Zealand, like most countries, maintained a small bank of frozen blood.
The red cells of donors with rare blood types were separated, treated with a protectant similar to glycerol, and frozen with liquid nitrogen.
Red blood cells frozen in this way lasted about 10 years.
"It is a very time-consuming process, but when you have rare blood groups and you need rare blood types, it's the only way we can achieve it," Dr Flanagan said.
"The reason we don't routinely freeze large volumes of blood is that the process for laying it down into the frozen blood bank and then recovering it is complex and time-consuming, so this isn't the type of blood that can easily be made available in emergency settings."
Dr Flanagan said that when a match for the Starship infant's blood could not be found in New Zealand, the blood service turned to the rare-blood donor registry kept by the International Blood Group Reference Laboratory in Bristol, England.
"Moving blood that's stored normally in liquid nitrogen across the world is a fairly complex logistical process," said Dr Flanagan.
"But that's why we have a national blood service, and our responsibility is to deal with the rare demands that are placed upon us in an effective and efficient way, and that's what we were fortunately able to do in this instance."
Auckland University blood expert Dr Graeme Woodfield, former chairman of the International Society of Blood Transfusion's working party on rare-blood donors, said New Zealand imported rare blood once or twice a year.
"But we often send blood overseas that we find here and think is rare."
Dr Woodfield said about 20 or 30 types of blood were known to be exceptionally rare all over the world.
