Trisomy of the long arm of chromosome No. 1 in human leukemia.

We encountered a karyotypic abnormality, i.e. a trisomy of part of or the whole long arm of chromosome No. 1, in 4 patients with leukemia; 3 with acute myeloblastic, leukemia (AML) and 1 with chronic myelocytic leukemia (CML) in the blastic phase. Q- and G-banding techniques revealed that in two patients with AML and in the one with CML, this karyotypic abnormality was not an initial one and was apparently associated with clinical progression of the disease. This chromosome change is a common karyotypic abnormality in blood disorders, especially in AML, and possibly bears a relationship to selective growth advantages of the leukemia cells.