MNS blood group system: a review.

The MNS blood group system is second only to the Rh blood group system in its complexity. Many alloantibodies to antigens in the MNS system are not generally clinically significant although antibodies to low-prevalence and high-prevalence MNS antigens have caused hemolytic disease of the fetus and newborn. The MNS antigens are carried on glycophorin A (GPA), glycophorin B (GPB), or hybrids thereof, which arise from single-nucleotide substitution, unequal crossing over, or gene conversion between the glycophorin genes. Antigens in the MNS system are fully developed at birth. This review summarizes aspects of the MNS system, including the molecular basis of some antigens in the MNS blood group system. Readers are referred to existing excellent reviews for background information. Throughout this document, information given without references can be found in the reviews listed previously, and the reader is referred to these reviews for references to original reports.