Anti-Mt^a associated with three cases of hemolytic disease of the newborn

The Mt^a antigen is a low-frequency red blood cell (RBC) surface antigen and is an established antigen of the MNSs blood group system. There has been one report of anti-Mt^a–induced hemolytic disease of the newborn (HDN) in the literature to date. We describe a family in which three children were affected by neonatal anemia. The clinical and hematologic findings were consistent with HDN, despite repeatedly negative direct antiglobulin tests (DAT) on cord RBCs. Serologic investigations showed that the mother’s serum contained anti-Mt^a. The father and all three children phenotyped as Mt^a+, while the mother was Mt^a–. Adsorption and elution experiments gave results which suggested that anti-Mt^a may be implicated in recurrent HDN in this family. Immunohematology 2002;18:37–39.