DOWN'S SYNDROME WITH NEONATAL ALLOIMMUNE THROMBOCYTOPENIA DUE TO HLA-A2 ANTIBODY.

Anti-HLA antibodies reportedly exist in the one third of pregnant women. But few occurrences of neonatal alloimmune thrombocytopenia (NAIT) caused by anti-HLA antibodies have been reported. Here a male baby, who was admitted for low birth weight with Down syndrome (DS), was suffered from thrombocytopenia without transient myeloproliferative disorder (TMD). Positive reactions of HLA-specific antibodies were detected in maternal serum. Cross-matching tests between maternal serum and paternal platelets and lymphocytes were strongly positive. It is most conceivable that the previous pregnancy of the mother induced the production of anti-HLA-A2 antibody, which crossed the placenta and subsequently caused an NAIT in the case presented. This is the first case of DS with NAIT due to anti-HLA antibodies.