Objectives : We have analyzed t(12;21)(p13:q22) in an attempt to evaluate the frequency and
prognostic significance of TEL-AML1 fusion gene in patients with childhood CD 10 positive B-ALL
by fluorescence in situ hybridization (FISH). Also, we have monitored the prognostic value of this
gene as a minimal residual disease (MRD).
Methods: All bone marrow samples of eighty patients diagnosed as CD 10 positive B-ALL in South
Egypt Cancer Institute were evaluated by fluorescence in situ hybridization (FISH) for t(12;21) in
newly diagnosed cases and after morphological complete remission as a minimal residual disease
(MRD). We determined the prognostic significance of TEL-AML1 fusion represented by disease
course and survival.
Results: TEL-AML1 fusion gene was positive in (37.5%) in newly diagnosed patients. There was a
significant correlation between TEL-AML1 fusion gene both at diagnosis (r = 0.5, P = 0.003) and as
a MRD (r = 0.4, P = 0.01) with favorable course. Kaplan-Meier curve for the presence of TEL-AML1
fusion at the diagnosis was associated with a better probability of overall survival (OS); mean
survival time was 47 ± 1 month, in contrast to 28 ± 5 month in its absence (P = 0.006). Also, the
persistence at TEL-AML1 fusion as a MRD was not significantly associated with a better probability
of OS; the mean survival time was 42 ± 2 months in the presence of MRD and it was 40 ± 1 months
in its absence. So, persistence of TEL-AML1 fusion as a MRD had no additive prognostic value over
its measurement at diagnosis in terms of predicting the probability of OS.
Conclusion: For most patients, the presence of TEL-AML1 fusion gene at diagnosis suggests a
favorable prognosis. The present study suggests that persistence of TEL-AML1 fusion as MRD has
no additive prognostic value.