Monosomy 7 in a girl with Ph1 positive chronic granulocytic leukemia

A case is reported of an 11-year-old girl with Ph1-positive chronic granulocytic leukemia. Very early in her illness the original 46,XX,t(9:22) cell population in the marrow became replaced by a second abnormal cell line, 45,XX,-7. This hypodiploid clone then remained dominant in the marrow until her death from myeloid blast crisis over 3 years later. It is suggested that the 45,XX,-7 cell line may have been induced by chemotherapy, and this possibility is discussed with particular reference to similar changes seen in secondary ANLL following treatment for lymphomas and other hematological malignancies.