Neonatal Thrombocytopenia in HLA‐DR, ‐DQ, ‐DP‐Typed Mother due to Rare Anti‐HPA‐1b (PLA2) (Zwb) Fetomaternal Immunization

A new case of rare neonatal alloimmune thrombocytopenia, due to an IgG anti‐HPA‐1b in a mother HPA‐1 (a+, b‐), was diagnosed using monoclonal antibody‐specific immobilization of platelet antigens. Clinically, it was similar to the 2 previously reported observations and confirmed that, in this particular case of anti‐HPA‐1b, the treatment with random platelet pools may be as effective as selected single‐donor platelet units when maternal platelets are unusable. The HLA‐DR, ‐DQ, ‐DP genotypes of the family were obtained by PCR‐SSO. The mother's typing, compared to the HLA‐DR of the 6 similar cases reported in Europe, suggests that a combined effect of two rare HLA haplotypes might enhance this immunization.