S-s-U-phenotype in a Caucasian family.

The S-s-U-blood group phenotype, commonly detected in Black populations, was found in a Caucasian family in which 4 homozygous U-negative members exhibit this phenotype. The erythrocyte blood group antigens and membrane glycoproteins from these donors have been serologically and electrophoretically characterized and compared to the U-negative red cells from Black people. Caucasian and Black S-s-U-red blood cells behaved identically since both lack Ss and U antigens and the minor red-cell membrane glycophorin B.