Abstract
The MNS system is a large, complex group of antigens, with 50 antigens at present. The major antigens of the system are carried on glycophorins A and B, which are important red cell sialoglycoproteins. Altered expression of MNS antigens is possible in cases where there is a formation of hybrid glycophorins. Some of these patients may make clinically significant antibodies which can be associated with hemolytic transfusion reactions (HTR) or hemolytic disease of the fetus and the newborn. This is a report of one such case with both these phenomena, in a multiparous woman. Incompatible cross-matches at the referral center caused the samples to be sent to this immunohematological laboratory where the serological profile was detailed. On sending the samples to a third blood group reference laboratory, gene sequencing was done and the antibody was identified. At this immunohematological laboratory, the phenotype was determined as M-N+. The patient's sera showed panreactivity with all panel cells (3-cell and 11-cell). At blood group reference laboratory, the findings were as follows- GYP (A-B) hybrid gene consistent with hemi/homozygosity for GYP*JL was confirmed and the panreactive antibody was identified as anti - En(a). Rare, atypical phenotypes in the MNS system can result from mutations affecting the sialoglycoproteins the antigens are carried on. The subset of antigens expressed in individual phenotypes varies and these patients can develop antibodies against the antigens they lack. When they present with immunohematological challenges such as panreactivity and incompatibility, a combination of serology, molecular technologies, and family studies help solve the problem. Alternatives to transfusion are also useful options in managing such cases.