Trisomy 13: A N e w Recurring Chromosome Abnormality in Acute Leukemia

A new recurring chromosome abnormality was identified in 8 of 621 consecutive successfully karyotyped adults with de novo acute leukemia. These eight patients had trisomy 13 as the sole cytogenetic abnormality. On central morpho-logic review, five cases were classified as subtypes of acute myeloid leukemia, one as acute mixed lymphoid and my-eloid leukemia, one as acute lymphoid leukemia, and one as acute undifferentiated leukemia. Blasts of all eight cases expressed one or more myeloid differentiation antigens. Three also expressed T-lineage-associated antigens; how-ever, none of these had rearrangement of the T-cell receptor B, 7, or 6 genes. Four of six cases tested were TdT positive. All eight patients with trisomy 13 were treated HE CLINICAL and potential biologic significance of T clonal chromosome abnormalities in acute leukemia has gained considerable attention in recent year^." ^ Wit