An unusual report of anti-N antibody presenting as ABO discrepancy in an old female patient in Palestine

The MNS is a highly complex immune blood group system which is almost equal to Rh in size and complexity. Anti-N antibody is naturally occurring in general, cold reactive IgM or IgG saline agglutinin and relatively rare when compared with anti-M. The immune type anti-N is seldom encountered. Anti-N antibody is not clinically significant unless it reacts at 37°C. Clinically significant anti-N antibody is reactive at 37°C or in the anti-human globulin phase, which may cause delayed hemolytic transfusion reactions or hemolytic disease of newborn. Here, we report a rare case presented as blood group discrepancy of a naturally occurring anti-N that reacts at 37°C.