Summary
Maternal alloantibodies to platelet specific antigens are a rare but important cause of severe thrombocytopenia in the fetus and neonate. Feto-Maternal Alloimmune Thrombocytopenia (FMAT) is most often due to anti-HPA-1a (PLA-1) or anti-HPA-5b (Bra). Anti-HPA-5a (Brb) however is extremely uncommon, with only 4 cases previously described. We report the first Australian case of feto-maternal alloimmune thrombocytopenia due to anti-HPA-5a.