Clonal origin of Philadelphia chromosome negative cells with trisomy 8 appearing during the course of alpha-interferon therapy for Ph positive chronic myelocytic leukemia.

The transient appearance of a Philadelphia chromosome (Ph) negative clone with trisomy 8 was found in the bone marrow cells from a patient with Ph positive CML during the course of alpha-interferon (IFN) therapy. To determine whether this clone was derived from a Ph positive clone or from some other cell lineage, we performed molecular cytogenetic studies on bone marrow cells from the patient by fluorescence in situ hybridization (FISH). No fusion of BCR-ABL could be detected in cells with trisomy 8, clearly indicating that the Ph negative trisomy 8 clone was not derived from the Ph positive CML population.