Reports of physical separation of ABL-BCR in non-deleted patients, as well as evolution from classical to variant Ph, introduce further heterogeneity to the vPh subgroup and raise the possibility that such translocations may herald disease progression.     ///    "We assessed the frequency of der(9) deletions, ABL-BCR abrogation, cytogenetic evolution and cryptic rearrangement in a large cohort of 54 patients with vPh CML. "    ///    The components of ABL-BCR were physically separated in a further 52% of patients while fused in the remaining 11%.     ///    "Deletion encompassing the reciprocal product (ABL-BCR) from the derivative chromosome 9 [der(9)] occurs in 15% of all patients, but with greater frequency in vPh patients. "    ///    "Deletions encompassing ABL-BCR were detected in 37% of patients, consistent with a model in which a greater number of chromosome breaks increases the risk of genomic loss. "