Neonatal alloimmune thrombocytopenia

Also known as NAIT. Caused by transplacental passage of maternal platelet-specific alloantibody and rarely human leukocyte antigen (HLA) allo-antibodies to fetuses whose platelets express the corresponding antigens. The antibodies are specific for platelet antigens inherited from the father but which are absent in the mother. Frequently, the thrombocytopenia is mild and the affected neonates remain largely asymptomatic. In cases of severe thrombocytopenia, the neonates may exhibit hemorrhagic complication at or a few hours after delivery. The most serious complication is intracranial hemorrhage.