Abstract
The antigens of the Cromer blood group system reside on decay accelerating factor (DAF), a protein belonging to the regulators of complement activation family. The blood group system consists of eight high-incidence antigens and three low-incidence antigens. The molecular basis for the antigens is known and, with the exception of IFC, each antigen is the product of a single nucleotide polymorphism in the DAF gene and has been localized to one of the four short consensus repeat regions on the DAF protein. The red blood cells (RBCs) of people with the Cromer null phenotype, Inab, lack DAF. Antibodies to Cromer antigens are rarely encountered although there is evidence that the antibodies may cause accelerated destruction of transfused RBCs. There is no risk of hemolytic disease of the newborn associated with Cromer system antibodies because the placenta is a rich source of fetally derived DAF, which is thought to adsorb the antibodies. Immunohematology 2002;18:95–103.