Background: Molecular cytogenetics is becoming one of the most useful tools targeting some genes which are generally considered to lead to leukemic transformation (as well as for numerical abnormalities). A fraction of acute lymphoblastic leukemia (ALL) cases carry the translocation t(9;22) (q34;q11.2) which juxtaposes the ABL proto-oncogene to the BCR gene generating a chimeric gene, BCR/ABL. This aberration is more frequent in adult ALL (20%-40%) than in pediatric ALL (<5%), and predicts poor clinical outcome. AIM OF OUR WORK: Is to study BCR/ABL fusion gene in ALL cases using fluorescent in situ hybridization.
Patients and methods: Twenty newly diagnosed ALL patients, 16 adult and 4 paediatric cases, were included in the study, 11 cases (55%) were of precursor B phenotype, 8 cases (40%) belonged to T lineage, while one case was biphenotypic expressing mainly precursor B cell markers tether with CD13, CD33, CD117, Detection of BCR/ABL fusion gene was done using interphase FISH technique and was confirmed molecularly using the RT-PCR technique.
Results: BCR/ABL fusion gene was negative in all the examined cases, yet abnormality involving 9q34, ABL gene, either by addition or deletion was detected in three cases (15%). Two of these cases were associated with BCR gene extra copies (three and four copies, respectively).
Conclusion: This may reflect the frequency of association of ABL gene and BCR gene abnormality in our cases, and that absence of fusion gene BCR/ABL does not exclude their role in the leukomogenic process, yet a larger study is required to confirm and detect the prevalence of these gene disturbances in ALL and their association.