[Diagnosis of chimerism based on blood group determination]

The authors report the results of blood group determinations in a 9-year-old girl in whom two populations of erythrocytes were discovered. The larger population accounting for nearly 80% of erythrocytes contained the antigen A2, the smaller population had the B antigen. Besides that differences were observed in the antigens of Duffy and Lewis systems. In the saliva A and H antigens were revealed. Familial investigations indicated the participation of two gametes of maternal origin (mother--AB, father--O) although no evidence of twin pregnancy was available. The cause of this chimaerism has not been explained.