[A Swiss family with the red cell antigen Pk (author's transl)]

The first Swiss family with the very rare bloodgroup Pk is described. It was possible to construct the family tree through 7 generations. Due to intermarriage between cousins, the 5 Pk people can be traced back to one of three ancestors. Coupling of the gene f[3], which leads to the production of the antigene Pk on erythrocytes when in homozygote condition, with an other blood group system, could not be recorded. Natural anti-P was found in all of the Pk peoples' serum. The haemolysing effect in an incompatible transfusion, probably due to anti-P, is shown in one example.