{Reference Type}: Case Reports
{Title}: Severe neonatal thrombocytopenia due to anti-HPA-4b alloantibodies: Third report described in a Caucasian mother.
{Author}: Petermann R;Bianchi F;Saib L;Ferré N;Francelle N;Oudin O;Chenet C;Mammasse Y;Jallu V;Chaussade A;Cornu A;Dubray L;Mailloux A;
{Journal}: Transfusion
{Volume}: 64
{Issue}: 6
{Year}: 2024 Jun 1
{Factor}: 3.337
{DOI}: 10.1111/trf.17863
{Abstract}: BACKGROUND: 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.
METHODS: 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.
RESULTS: 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.
CONCLUSIONS: 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.