Triplets with neonatal alloimmune thrombocytopenia due to antibodies against human platelet antigen 1a.

BACKGROUND

Neonatal alloimmune thrombocytopenia (NAIT) has been reported only rarely in twins and not at all, to our knowledge, in triplets.

CASE REPORT: 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.