A scarce Sarah: new blood group making transfusions safer

Further research into a rare blood type first recorded in Australia 20 years ago will continue to make transfusions and pregnancies safer for others.

“Now families with the SARA blood type can be tested for the gene and this will help safely manage future pregnancies,” says Associate Professor Catherine Hyland of the Australian Red Cross Blood Service.

“This genetic testing has implications for others, particularly since similar problems can occur during transfusion or pregnancy for people with similar rare blood types.”

Blood types are more complex than simply combinations of ‘positive’ and ‘negative’ with A, B, O, or Rh—there are hundreds of different antigens (proteins and sugars on the surface of our cells) across the 36-plus blood groups.

In the 1990s, the Australian Red Cross Blood Service realised the antigens on a special donor named Sarah’s red blood cells weren’t like any previously recorded. But it wasn’t until 2010 that the unusual antigen was investigated again: the Canadian Blood Service reported that a pregnant woman’s immune system had begun attacking her foetus, which they suspected had inherited the same rare blood type recorded in Australia.

Rhiannon McBean, who was then a PhD student with the Blood Service, made use of the advances in genetic sequencing technology to compare masses of data from samples from both the Canadian and Australian families, to finally isolate the gene responsible for the blood type.

“We had this wonderful ‘Eureka’ moment,” says Catherine, who was Rhiannon’s co-supervisor.

The discovery was recognised by a vote at the International Society of Blood Transfusion, and officially endorsed as a new blood type, named ‘SARA’, in honour of the donor.

Catherine and her colleagues at the Blood Service are working with Australian samples to determine how frequent SARA and other unusual blood types are, and would like to expand the research internationally.  

Australian governments fund the Blood Service to provide blood, blood products and services to the Australian community.

For more information:

Australian Red Cross Blood Service
Alison Gould
+61 2 9234 2390