Fetal Alloimmune Thrombocytopenia (FAT) is one of the leading causes of neonatal thrombocytopenia and, in its most severe cases, can lead to intracranial hemorrhage and death. The obstetric management of FAT is still very controversial, in terms of surveillance and medication.
In the literature there are reports of FAT against one or two different haplotypes. We present the case of a couple whose first newborn baby presented with thrombocytopenia and was diagnosed with FAT. Alloimmunization occurred in this pregnancy against haplotypes HPA-1 and HPA-3. Parental genotype analysis showed homozygosity for different alleles for two haplotypes (HPA-1 and HPA-3) and maternal heterozygosity and paternal homozygosity for HPA-15, meaning that a second pregnancy could result in FAT against three different haplotypes. We describe the follow up and therapeutic approach in the second pregnancy. The second newborn baby was born with a normal platelet count. The newborn baby was found to have three different haplotypes compared to his mother (HPA-1, HPA-3 and HPA-15). To the best of our knowledge this is the first case described in the literature of FAT against three different haplotypes.
Vicente F, Serra C, Calado C, Matviyuk L and Almeida D