We therefore propose that the potential of the immunogenotype to diversify depends primarily on the stage of IG/TCR gene configuration of the cell in which the ETV6/RUNX1 gene fusion takes place..     ///    " Recent data suggest that late relapses evolve from an ancestral ETV6/RUNX1-positive (also designated TEL/AML1-positive) clone resulting from secondary changes (ETV6 deletion) that differ from those of the initial leukemia and, as a consequence, may also deviate in their clonotypic immunoglobulin/T-cell receptor (IG/TCR) gene rearrangements. "    ///    Clonal variation of the immunogenotype in relapsed ETV6/RUNX1-positive acute lymphoblastic leukemia indicates subclone formation during early stages of leukemia development.. 