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An international consortium of researchers, BloodGen, is developing a new form of genetic blood test that will provide much closer matching between blood samples and transfusion recipients. BloodGen, which includes experts from Germany, Sweden, Spain, the Czech Republic and the Netherlands, as well as the UK, seeks to “validate and standardise molecular genotyping approaches to large-scale blood group diagnosis and to prove its superiority over currently applied serological testing”. Normal serological testing of blood checks for the major blood group antigens, or cell surface markers, to determine whether blood is type A, B, AB or O, and whether it is Rhesus positive or negative. Transfusion recipients must be given blood that matches their own blood group, otherwise dangerous complications will arise as their immune systems will attack the apparently ‘foreign’ blood cells (alloimmunisation).However, even with the normally safe blood typing process, recipients of multiple blood transfusions (such as people with leukaemia or haemophilia) can over time develop dangerous immune responses against the donated blood cells, due to mismatch between other, less important, blood cells markers.

The new Bloodchip test will use DNA microarray (gene chip) technology to allow the rapid identification of a much larger number of minor blood cell markers. This would make it possible to make much more accurate matches between donated blood and recipients, reducing the number of cases of alloimmunisation. The Bloodchip could detect up to 116 distinct DNA signatures or profiles associated with blood groups. Currently in a large-scale EU pre-clinical trial, the developers hope that the Bloodchip test will lead to the routine use of molecular genotyping of blood groups across the EU.

UK National Blood Service Research Director Professor Marion Scott commented: "The Bloodchip test will literally be a lifesaver for those who suffer from illnesses that require multiple blood transfusions such as haemophilia, sickle cell disease and thalassaemias…The Bloodchip test will be of enormous benefit in ensuring those with these disorders receive perfectly matched blood to enable them to better manage their conditions" (see BBC news report).