Comparative sequence analysis of incomplete DJH and TCR gene rearrangements in children with relapses of T-ALL

The detection of minimal residual disease (MRD) during the first phase of treatment can predict outcome in childhood acute lymphoblastic leukemia (ALL).1 Currently MRD detection in ALL patients provides important information in order to assign a tailored-treatment and the risk of an impending relapse. Nevertheless, the major treatment failure in ALL occurs predominantly in patients with T-cell ALL. This reflects especially a more therapy-resistance and a slower clearance of blasts of T-ALL in comparison with precursor-B-ALL.2 Therefore, the quantification of early response to therapy and the monitoring of MRD during and after treatment can greatly improve the outcome and long-term quality of life of these patients. In childhood ALL, detection of MRD with high sensitivity (ie 104, 105) can be achieved by quantitative PCR methods (RQ-PCR) of rearranged immunoglobulin (Ig) and T-cell receptor (TCR) genes.1,3 The usefulness of these specific PCR targets should give attention to the possible modification of Ig and TCR gene rearrangements that could occur during the course of disease, due to continue activity of the V(D)J recombinase enzymes in leukemic blasts