%0 Case Reports
%T Severe neonatal thrombocytopenia due to anti-HPA-4b alloantibodies: Third report described in a Caucasian mother.
%A Petermann R
%A Bianchi F
%A Saib L
%A Ferré N
%A Francelle N
%A Oudin O
%A Chenet C
%A Mammasse Y
%A Jallu V
%A Chaussade A
%A Cornu A
%A Dubray L
%A Mailloux A
%J Transfusion
%V 64
%N 6
%D 2024 Jun 1
%M 38693097
%F 3.337
%R 10.1111/trf.17863
%X <B>BACKGROUND: </B>Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT) results from maternal platelet alloimmunization against paternal antigens inherited by the fetus, most often due to the Human Platelet Antigen (HPA)-1 system in Caucasians. We investigated in 2023, a 30-year-old Caucasian woman Gravida 2 Para 1 who gave birth at 35 weeks of gestation to a male (body weight 2210 g) without signs of bleeding. A severe thrombocytopenia (platelet count at 3 G/L) was discovered incidentally a few hours after delivery in the context of the management of a respiratory distress. The newborn recovered after one platelet concentrate transfusion and normalized his platelet count at Day 5.<BR><B>METHODS: </B>FNAIT investigation was performed according to guideline recommendations. Platelet genotyping was carried out by multiplex PCR. Maternal serological investigation included Monoclonal Antibody-specific Immobilization of Platelet Antigens method (MAIPA) and Luminex technology.<BR><B>RESULTS: </B>Parental and newborn genotyping pointed out an HPA-4 incompatibility between the mother and the newborn and the father. Serological investigation revealed an anti-HPA-4b alloantibody confirming the diagnosis of neonatal alloimmune thrombocytopenia.<BR><B>CONCLUSIONS: </B>We described the third case of anti-HPA-4b alloantibody discovered in a Caucasian mother. This case strengthens the need for reference laboratory to genotype a panel of HPA alleles reflecting local genetic population diversity and for crossmatch of maternal serum with fresh paternal platelets in clinical suspected cases of neonatal alloimmune thrombocytopenia.