Abstract
Philadelphia chromosome (Ph) is found in more than 95% of Chronic Myeloid Leukaemia
(CML) patients arising from the reciprocal translocation of chromosomes 9 and 22 which
results in the formation of chimeric fusion gene BCR-ABL. This paved the path for
targeted gene therapy in CML and thus plays a pivotal role in diagnosis and prognosis.
Fluorescence in situ hybridization (FISH) is a rapid and reliable technique in molecular cytogenetics
to detect BCR-ABL fusion signal in both interphase and metaphase spreads of bone marrow
sample. Peripheral blood white cells as a surrogate for bone marrow have been suggested
by a few studies.
The objective of the study was to evaluate FISH on peripheral blood specimen as a
rapid and reliable method to quantify Ph positive cells in a patient with Chronic
Myeloid Leukaemia. FISH was performed on interphase nuclei from cultured peripheral
blood sample of the patient using BCR/ABL Translocation, Dual fusion probe. Chromosomal
analysis was performed by GTG banding technique. FISH and karyotyping confirmed the
presence of reciprocal translocation t (9; 12) (q34.1; q11.2).
Our results confirmed that FISH technique is a rapid, sensitive, quantitative technique
which can be used for the evaluation of CML using peripheral blood. FISH helps in
the detection of minimal residual disease and disease recurrence with small percentage
of abnormal cells. In our experience, this situation is usually associated with very
high WBC count which can result in increase in the percentage of Phpositive cells.
Keywords
Fluorescence in situ hybridization (FISH) - chromosomal analysis - chronic myeloid
leukemia - peripheral blood