Detection of clonality by heteroduplex analysis of amplified junctional region of T-cell receptor gamma in patients with T-cell acute lymphoblastic leukemias

Institute of Hematology L e A. Seragnoli, University of Bologna, Italy.

BACKGROUND AND OBJECTIVE: Traditional gel electrophoresis of PCR amplification products of regions from T-cell receptor genes often does not differentiate monoclonal from polyclonal rearrangements. We used polymerase chain reaction (PCR) and heteroduplex analysis on polyacrylamide gels to improve the detection of monoclonal rearrangements. METHODS: We investigated heteroduplex analysis of the amplified V gamma-J gamma junctions of the rearranged T-cell receptor gamma (TcR-gamma) gene by electrophoretic separation on non-denaturing polyacrylamide gel (PAGE) in 8 T-cell acute lymphoblastic leukemia (T-ALL) patients analyzed at diagnosis. RESULTS: Clonal homoduplex and heteroduplex bands were present only in the T-ALL samples and not in controls. We confirmed clonality by direct sequencing of the V gamma-J gamma junction. In 2 instances the analysis was performed on samples obtained from the same patient at diagnosis and at relapse, respectively; the presence of the same clonal TcR-gamma rearranged cell remained detectable during clinical progression of the disease. INTERPRETATION AND CONCLUSIONS: Our heteroduplex analysis showed that separation of the PCR product by electrophoresis on non-denaturing PAGE is a rapid and convenient method for the detection of clonal TcR-gamma rearrangements in T-ALL.

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