Maternal HLA Type and Fetal/Neonatal Alloimmune Thrombocytopenia

Investigators from multiple institutions conducted a meta-analysis to assess the association between HLA-DRB3*01:01 status (positive or negative) and both development of human platelet antigen 1a (HPA-1a) immunization and severe fetal/neonatal alloimmune thrombocytopenia (FNAIT) in mothers who initially are HPA-1a–negative. For the meta-analysis, the authors identified published studies that included ≥5 newborns with severe FNAIT (defined as a platelet count <50 × 10⁹/L) and included maternal HLA-DRB3*01:01 and HPA-1a status. The selected studies were classified as prospective or retrospective. For the group of prospective studies, the likelihood of an HLADRB3* 01:01–negative and HPA-1a–negative mother becoming HPA-1a immunized was compared to that of an HLA-DRB3*01:01–positive mother, and the odds ratio (OR) calculated. In addition, the OR for giving birth to a …