t(1 ;2), inv(1) and Trisomy 1q during the Blastic Phase of Philadelphia Chromosome-Positive Chronic Myeloid Leukemia

Abstract

Several karyotype changes observed during the blastic phase in 2 patients with Philadelphia chromosome (Ph)-positive chronic myeloid leukemia (CML) are reported. Rearrangements involving chromosome 1, i.e., translocations, a pericentric inversion and trisomies of its long arm, are described. In the first patient whose chronic phase was very long (17 years), the uncommon association between i(17q) and Ph duplication has been observed during the blastic phase, beside the involvement of chromosome 1. In the second patient, additional abnormalities involving chromosomes 1, 2, 4, 8, 18 and 21 were present. Of particular interest is the finding of a t(1;2). In this case, the presence of hyperdiploid cells with 49–50 chromosomes, prevailing at the blastic crisis, was due to the evolution of the hypodiploid clone with the 45, XX, t(9;22),-21 karyotype found during the chronic phase. The occurrence of chromosomal changes involving chromosome 1 during the blastic phase of CML is emphasized.