Pedigrees of the index family and the Kr family.

In the Iy (index) family (A), the family member with the index case of neonatal alloimmune thrombocytopenia (NAIT) is marked with an asterisk (A.III.2). A third pregnancy was interrupted because of massive intraventricular bleeding in the fetus (A.III.3). All individuals were phenotyped with use of the monoclonal antibody-specific immobilization of platelet antigens assay. Material for genotyping was available only from individuals A.I.1, A.I.2, and A.II.1. One member of the Kr family (B) was found in assessing 300 healthy blood donors. All individuals were phenotyped and genotyped. No case of NAIT was observed in the Kr family.