Immunization against a new, infrequent alloantigen (Iy) on the platelet glycoprotein Ib/IX as a cause of a serious case of neonatal alloimmune thrombocytopenia

Neonatal alloimmune thrombocytopenia is the consequence of maternal alloimmunization against platelet-specific alloantigens, usually PIA1 or Br(a). The clinical picture is characterized by signs of haemorrhagic diathesis as a result of marked thrombocytopenia. In the last years, rare cases of immunization against 'low-frequency' or 'private' platelet alloantigens on the platelet glycoprotein (GP) complex IIb/IIIa have been found. This is the first report on NAIT due to maternal immunization against a low-frequency platelet alloantigen ('Iy') localized on platelet GP Ib/IX.