Starting from the famous discovery of blood groups, precisely the first blood group system ABO by Karl Landsteiner in 1900-1901, until 2011 30 blood group systems were described, including approximately 300 red blood cells (RBCs) antigens (1). The classification and nomenclature of RBCs antigens are supervised by the International Society of Blood Transfusion – ISBT. In the group system there must be at least one antigen, which means that there must be persons producing antibodies against that antigen, absent in them. The biochemical structure of the antigen, the way of inheritance and gene sequence, as well as the antithetic allele must be described. Usually, the biological role of the antigen or the membrane structure connected with it are studied. In 2012 we described three new group systems in “Progress in Medicine” (2); on one of them, named earlier P, much new information regarding biochemical structure and the way of inheritance was obtained in 2011, and its name was changed into P1PK; publications on two other, at that time new, systems: Lan and Junior were issued in January 2012. Earlier, two common antigens: Lan i Jr^a were known. Their lack, detected in few persons, resulted in alloantibodies production after transfusion and pregnancy, which provided very serious clinical problem, connected with the lack of donors without these antigens. In 2012 the genetic basis was described, meaning the alleles and phenotypes with and without these antigens, as well as their biochemical structure and the function of proteins carrying these antigens. In this way, the criteria of creating of the new group system were fulfilled (3, 4); they took places 32 and 33. In the same year, the group system Forssman was introduced into classification, followed by Vel system in 2013 and CD59 system in 2015 (5). In the case of the Vel system, the situation was similar to Lan and Jr^a, which means, that common antigen Vel was previously known, however the antithetic allele, coding the phenotype Vel negative, the biochemical structure and carrying protein were not known. Characterization of this items enabled the description of the group system. The circumstances of discovery of Forssman and CD59 systems were different and quite surprising. We will describe these three new group systems.

ISBT 031, symbol: FORS, antigens number: 1, gene: GBGT1 on chromosome 9 (1, 6).

Antigen is biochemically similar to human group system antigens ABO, P1PK, H, Lewis, I, GLOB. They are all carbohydrates and their specificity depends on the type of the last sugar in glycoprotein or glycolipid chain in red blood cell membrane. It was described in 1911 by Forssman. Since then, the antigen, named after its discoverer, was considered typical for many mammals, excluding primates and human. It was described in dogs, sheep, horses, guinea pigs and mice. Gradually, the antigen structure, the way of inheritance and biological role were discovered. The gene codes protein of the enzyme incorporating N-acetylgalactosamine into appropriate precursor carbohydrate chain. The antigen acts as the receptor for various bacteria. In human, lack of Forssman antigen leads to the creation of natural heterophile antibodies, named Forssman antibodies, which may be the part of the immune response to some infections. At the same time, people have the A antigen, in which the last sugar, N-acetylgalactosamine is the same as in Forssman antigen.