title: Severe neonatal alloimmune thrombocytopenia due to anti-HPA-3a.
abstract: OBJECTIVE
  Neonatal alloimmune thrombocytopenia is usually attributable to HPA-la antibodies. We report a case of parental platelet antigen incompatibility associated with a severe neonatal thrombocytopenia secondary to alloimmunization to HPA-3a.
  
  
  METHODS
  Platelet antibodies were detected by the monoclonal antibody-specific immobilization of platelet antigens, genotyping of the platelets by PCR, and HLA typing by serologic procedures and PCR.
  
  
  RESULTS
  Genotyping of maternal and paternal platelets confirmed the incompatibility in the HPA-3a system. It is noteworthy that the mother is of the HLA type DRB3*0101, is ABO-incompatible with her husband, and also has HLA class I antibodies.
  
  
  CONCLUSIONS
  Severe neonatal thrombocytopenia associated with HPA-3a alloimmunization is infrequent and all the factors mentioned above could have played a role in the severity of the disease.
authors.affiliation: Medical Clinics II, Department of Medicine, University Hospital, Geneva, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Boehlen
authors.forename: C
authors.initials: C
authors.lastname: Kaplan
authors.forename: P
authors.initials: P
authors.lastname: de Moerloose
mesh_terms: D000328:Adult; D016824:Antigens, Human Platelet / Q000276:immunology*; D001787:Blood Group Incompatibility; D001792:Blood Platelets / Q000276:immunology*; D003131:Combined Modality Therapy; D005260:Female; D006684:HLA-DR Antigens / Q000032:analysis; D059826:HLA-DRB3 Chains; D006801:Humans; D007112:Immunity, Maternally-Acquired; D016756:Immunoglobulins, Intravenous / Q000627:therapeutic use; D007231:Infant, Newborn; D007518:Isoantibodies / Q000276:immunology*; D007567:Jaundice, Neonatal / Q000209:etiology / Q000276:immunology; D017713:Platelet Transfusion; D011247:Pregnancy; D013921:Thrombocytopenia / Q000151:congenital / Q000209:etiology / Q000276:immunology* / Q000628:therapy
chemical_list: C044561:3a alloantigen, human; D016824:Antigens, Human Platelet; D006684:HLA-DR Antigens; D059826:HLA-DRB3 Chains; D016756:Immunoglobulins, Intravenous; D007518:Isoantibodies