A Pair of Newborn Human Blood Chimeric Twins

Abstract

A pair of newborn, clinically normal, diamniotic, dichorionic twins, a group A 2 boy and a group O girl, were found on routine blood grouping to be chimeras. In each about 85 per cent of the red cells were of the girl's type, O, the chimerism also being evident in the MNSs, Rh, Kell and Kidd systems. Of the girl's cultured white cells 70 per cent were XX, 30 per cent XY, while of the boy's 78 per cent were XX, 22 per cent XY. A greater per cent of the boy's than of the girl's polymorphs had drumsticks, but his polymorphs were more numerous and more mature than hers. The red cell percentages had not changed up to three months after birth.