ABSTRACT
Currently, many forms of leukemia are considered potentially curable, with prognosis and clinical outcome strongly dependent on the underlying molecular pathophysiology. A substantial number of leukemia patients harbor nonrandom katyotypic abnormalities that define subgroups with unique biological and clinical features. The aim of this work was to-identify precisely some specific genetic changes in childhood precursor B-cell acute lymphoblastic leukemia [Pre B-ALL] by molecular techniques. reverse transdiption-polymerase chain reaction [RT-PCR] was used to detect genetic lesions with their characteristic mRNA splicing variants, occurring in pretreatment de novo 21 children with Pre B-ALL. These included ABL gene product, [9;22] [q34;q11] with BCR/ABL P190 and P210 isoforms and t[1:l9] [q23;p13] with E2A/PBX1. Fluorescence in situ hybridization [FISH] was used to detect t[12;2l] [p13;q22] with TEL/AML1 fusion. 90.5% of childhood pre B-ALL was positive for ABL transcript [including a subgroup with weak positive results representing 14.3% of the total cases] and 9.5% showed negative results. BCR/ABL P190 fusion transcript was detected in 4.8% and BCR/ABL P190/P210 coexpression was detected in 4.8% of cases. t [l;19] was detected in 4.8% of the studied cases, while t[12;21] was detected in 14.3% of the cases. MI children with positive translocation transcripts were below the age of 8 years. RT-PCR and FISH are reliable tools in the clinical screening of leukthnia patients for the presence of specific gene rearrangements with important diagnostic and prognostic implications that may prepare the stage for new classification based on genotyping