title: Triplets with neonatal alloimmune thrombocytopenia due to antibodies against human platelet antigen 1a.
abstract: BACKGROUND
  Neonatal alloimmune thrombocytopenia (NAIT) has been reported only rarely in twins and not at all, to our knowledge, in triplets.
  
  
  METHODS
  Nonidentical triplets were born with severe thrombocytopenia. Nadir platelet (PLT) counts were 17 × 109, 12 × 109, and 10 × 109/L. NAIT was confirmed by an incompatibility for human PLT antigen (HPA)-1a and the presence of maternal anti-HPA-1a. The maternal genotype was HPA-1bb and the paternal genotype was HPA-1aa; thus, all children were affected.
  
  
  RESULTS
  PLT counts for each infant improved with the administration of random-donor PLT transfusions. All three infants also received intravenous immunoglobulin. None had major bleeding. A small isolated subependymal hemorrhage was found incidentally in one infant; this remained stable on repeat imaging.
  
  
  CONCLUSIONS
  This is the first report of triplets with NAIT. Anti-HPA-1a is sufficiently potent to affect three infants simultaneously. Random-donor PLTs were effective in improving PLT counts in all three infants.
authors.affiliation: Department of Pediatrics, Division of Pediatric Hematology and Oncology, McMaster Children's Hospital, McMaster University, Hamilton, ON.
authors.forename: Ziad
authors.initials: Z
authors.lastname: Solh
authors.affiliation: Department of Pediatrics, Division of Pediatric Hematology and Oncology, McMaster Children's Hospital, McMaster University, Hamilton, ON.
authors.forename: Vicky
authors.initials: V
authors.lastname: Breakey
authors.affiliation: Department of Pediatrics, Division of Neonatology, University of Calgary, Calgary, AB.
authors.forename: Prashanth
authors.initials: P
authors.lastname: Murthy
authors.affiliation: Department of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, ON.
authors.forename: James W
authors.initials: JW
authors.lastname: Smith
authors.affiliation: Department of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, ON.
authors.forename: Donald M
authors.initials: DM
authors.lastname: Arnold