Molecular detection of BCRABL fusion gene in saudi acute lymphoblastic leukemia patients

الملخص EN

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 ; qll.2) which juxtaposes the ABL proto-oncogene to the BCR gene generating a chi-meric 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 ami Methods : Twenty newly diagnosed ALL patients, 16 adult and 4 paediatric cases, were included in the study, II 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 CD 13, 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 asso-ciation of ABL gene and BCR gene abnormality in our cases, and that absence of fusion gene BCR / ABL docs 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.