Clinical approach after identification of a rare anti-Ena in a prenatal sample

CONCLUSIONS: The antigens associated with the MNS blood group system (ISBT 002) are located on glycophorin A (GPA) and glycophorin B (GPB). The most frequently encountered antibodies to antigens in this system by a transfusion medicine service are those directed against M, N, S, and s. Individuals lacking GPA typically have red blood cells that lack M, N, and Ena, whereas those lacking both GPA and GPB lack M, N, and Ena as well as S, s, and U. Such individuals may develop a rare antibody, anti-Ena, directed against determinants on GPA. This antibody is capable of causing hemolytic transfusion reactions and hemolytic disease of the fetus and newborn. This case report describes a pregnant woman found to have anti-Ena. Molecular testing supported an Mk phenotype that was found in several members of her immediate family.