We have identified three ABCG2 alleles that are newly associated with weakened Jr(a) expression. One of these is novel, the missense allele c.1714A>C (Ser572Arg) and two that have been previously described c.421C>A (rs2231142; Gln141Lys) and c.1858G>A (rs34783571; Asp620Asn). In addition, we found a novel, presumed null allele, c.1017_1019delCTC (Ser340del).

Cold-reactive autoagglutinins may mask the presence of underlying clinically significant alloantibodies. Adsorption with rabbit red blood cells (RBCs) or stroma can remove cold autoagglutinins found in the patient's plasma/serum that are directed towards antigens expressed on the surface of rabbit RBCs. By removing these cold autoagglutinins, it is then possible to determine whether any underlying alloantibody reactivity is present. Although this method may also unintentionally adsorb alloantibodies directed towards antigens found on rabbit RBCs, it is still a widely used and convenient method to remove cold autoagglutinins.