Cytogenetic characterization of ten cases of Ph 1-positive acute myelogenous leukemia

Abstract

Chromosome banding analyses were made on 10 cases of Ph 1-positive AML (7 M1 and 3 M2). The standard type Ph 1 translocation, t(9q+; 22q−), was identified in all of them. Karyotypically normal cells were observed in 6–65% of bone marrow metaphases at the initial cytogenetic examination of 7 patients, whereas the remaining 3 patients had only Ph 1-positive cells at diagnosis. Follow-up studies performed in 5 cases indicated that the frequency of karyotypically normal cells increased up to 81–100% when the patients were in remission, whereas it was much reduced in relapse. In 5 cases, there was observed a clone of cells in which the Ph 1 translocation was the sole karyotypic abnormality. Various types of other chromosome abnormalities, in addition to the Ph 1, were observed in all cases, among which −7 was the most frequent, being found in three cases as a stem line. Other additional changes encountered were +Ph 1, del(5), i(17q), −10, +18, +X, and various numerical and structural changes including certain secondary translocations that occurred in the Ph 1 (22q−) or its partner (9q+). The types and frequencies of these additional changes appeared to be different from those found in the acute phase of CML or in Ph 1-positive ALL.