DETECTION OF M-BCR ABL FUSION BY FLUORESCENCE IN-SITU HYBRIDIZATION (FISH) IN A CASE OF PH-NEGATIVE CML/

A balanced reciprocal translocation, t(6;9)(p21;q34), was identified i n a female patient diagnosed with chronic myeloid leukemia (CML). Both homologs of chromosome 22 were of normal length and morphology. South ern blotting revealed a bcr rearrangement with BglII and HindIII. Two signals for the abl probe were demonstrated by fluorescence in situ hy bridization (FISH), one on the normal chromosome 9 and the second on a chromosome 22. Thus, molecular rearrangement of bcr resulted from ins ertion of an abl gene within the bcr region despite absence of a Ph ch romosome.