New blood group system discovered by Swedish researchers

When giving blood transfusions, it is essential to take different blood groups into account. ABO and Rh are just two of many blood group systems; now a new one has been added. The system, which is the first one to have been discovered in Sweden, has been mapped by researchers at Lund University and Gothenburg University. The molecule in question had previously only been found in the blood of lower mammals.

The new blood group system has been named FORS after its original finder, Lund John Forssman.

“He identified this blood group molecule as early as 1911, so the discovery recently celebrated its 100th birthday. But at the time, he only found the blood group in dogs, horses, sheep and other mammals, whereas now, for the first time, we have found it on red blood cells from humans”, says Professor of Transfusion Medicine Martin L Olsson of Lund University.

A blood group system refers to a collection of antigens, which are varieties of a particular molecule on the surface of the red blood cells. Antigens are foreign substances that stimulate the immune system into producing antibodies. For example, a person with blood group A produces antibodies against blood from group B and cannot be given that type of blood in a transfusion without serious consequences.

In the case of the FORS blood group, the distinction is between an individual either having the FORS antigen or producing antibodies against it (anti-FORS), which is most common. The FORS system will now be a further factor to consider in blood transfusions.

“There were actually some blood donors among the people we identified as having the FORS antigen. If this had led to serious reactions in anti-FORS patients who were given their blood, it would have been noticed. Even so, our test-tube experiments indicate that certain blood transfusion recipients might have problems. In addition, even weak reactions can have serious consequences for patients with blood disorders, for example, who often need transfusions”, says Martin L Olsson.

Therefore, he and his colleagues want to develop a way of routinely testing blood donors’ blood for the FORS blood group, as is already done with DNA technology for other blood groups. Until more is known on the blood’s possible side-effects, donated blood of this type should be used for laboratory purposes rather than healthcare.

The gene which can give rise to the FORS antigen is present in all humans. Most of us have it in an inactive form, however, which is the reason why John Forssman only found this blood group in animals. Doctoral student Annika Hult, who is part of the Lund team, has discovered that the gene in the FORS carriers has "receded in evolution" by mutating back to the same active form seen in dogs, for example.

This can also be a problem, since we know that bacteria such as E.coli can bind to cells that express FORS.

“Dogs can get urinary tract infections through E.coli bacteria which bind to their cells. If the bacteria that normally only infect animals can also affect humans with FORS, these individuals may run a special risk of disease”, points out Martin L Olsson.

Publication:


Title: Forssman expression on human erythrocytes: biochemical and genetic evidence of a new histo-blood group system
Authors: Lola Svensson, Annika K. Hult, Robert Stamps, Jonas Ångström, Susann Teneberg, Jill R. Storry, René Jørgensen, Lennart Rydberg, Stephen M. Henry, and Martin L Olsson.

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