Recently the use of allele-specific oligonucleotide probe typing for PlA (HPA-1) antigens has been described to determine the risk of second or subsequent fetuses in families where one infant had the diagnosis of anti-PlA1 (HPA-1a)-mediated NAIT (McFarland et al., 1991a).
Maternal alloantibodies against the five common human platelet antigen (HPA) systems (HPA-1 to -3, -5, and -15) are found in only 20% of cases referred for fetal and neonatal thrombocytopenia (FMAIT) investigations.
Prenatal typing for the human platelet antigens-1 (HPA) permits identification of a fetus at risk for neonatal alloimmune thrombocytopenia (NAITP) in cases of HPA-1 incompatibility in which the father is heterozygous for the HPA-1a antigen.