Cytogenetic evidence of the intrauterine origin of acute leukemia in monozygotic twins.

THE APPEARANCE in childhood of acute leukemia in one member of a monozygotic twin pair is frequently followed within a few months by the appearance of the same disease in the other twin. Concordance of acute leukemia in monozygotic twins can be as high as 20 per cent.1 2 3 Although common postnatal leukemogenic events may explain this concordance, a more attractive hypothesis, proposed by Clarkson and Boyse,4 is based on the fetal circulation of monozygotic twins: a single leukemic transformation occurs in utero and leads to the establishment of the malignant clone in each twin; the common placental blood of monozygous . . .