P53 gene mutations in chronic myelogenous leukemia medullary and extramedullary blast crisis.

Molecular alterations of the P53 gene were investigated in 27 unselected patients with chronic myelogenous leukemia (CML) blast crisis. A rearrangement of the P53 gene was evident by Southern blotting in 3 cases, one of which also showed the same alteration in the chronic phase. Single strand conformation polymorphism and sequencing analysis showed point mutations in 4 blast crisis cases. Of interest, P53 point mutations were evident in all the 3 cases of extramedullary blast crisis examined and the same point mutation was found in the myeloblastoma tissues and in the subsequent peripheral blast cells. These data indicate that: a) P53 gene mutations occur in a significant but not a large number of CML acute phase cases; b) P53 gene point mutations seem to correlate strongly with the infrequent extramedullary presentation of the blast crisis; c) the presence of the same P53 gene point mutation in extramedullary and bone marrow blast cells confirms the common clonal origin of the two cellular populations.