Interphase FISH and morphologic analysis of AML

Interphase cytogenetic analysis of peripheral white blood cells from a patient with acute myelogenous leukemia (AML) who was previously diagnosed with trisomy 8 was performed for the purpose of documenting clonal response to intensive chemotherapy. DNA in situ hybridization was performed using a probe specific for chromosome 8 α-satellite DNA sequences. Cells were stained with Wright stain prior to interphase analysis and photographed to allow correlation of cell morphology with abnormal karyotype. Prior to chemotherapy, the patient's leukocyte differential contained 8% blasts; interphase analysis revealed 23% trisomy 8 cells, including mature granulocytes. Forty days after the start of chemotherapy, at which point the patient had attained clinical remission, interphase analysis revealed only 2% cells with three signals, which was not statistically significant when compared with our own series of controls. The use of interphase FISH analysis in this case provides additional evidence that some leukemic blasts may be capable of limited differentiation in vivo and also suggests a differential sensitivity to chemotherapy between cytogenetically normal and abnormal hematopoietic precursor cells.