BCR and chronic myelogenous leukemia, BCR-ABL1 positive: We previously observed the oligoclonal TCR Vβ21 gene at a high frequency (26.4%) in CML using RT-PCR-Genescan technology, and in vitro oligoclonal Vβ21 T cells from cord blood could be induced by K562 cells, CML cells,as well as a BCR-ABL fusion peptide.