“…Tyrosine kinase inhibitors (TKIs) suppress the Ph + cell clone, restoring polyclonal hematopoiesis 2 . However, clonal cytogenetic abnormalities in Ph − cells become detectable in some patients achieving a cytogenetic response to TKIs, and slow evolution to myelodysplasia or acute myeloid leukemia (AML) has been observed 2, 3 . In rare cases, identical abnormalities were demonstrated both in Ph + and Ph − cells, but most cases are consistent with independently acquired abnormalities, although an undetected common ancestral event cannot be excluded (reviewed in 4 ).…”