Translocation (4;15)(p16;q24): A Novel Reciprocal Translocation in a Patient with BCR/ABL Negative Myeloproliferative Syndrome Progressing to Blastic Phase

A patient with BCR/ABL negative myeloproliferative syndrome with a 46,XY,del(3)(q21),t(4;15)(p16;q24) karyotype is described. Fluorescence in situ hybridization performed with chromosomes 4 and 15 painting probes confirmed a novel reciprocal (4;15) translocation. The absence of crkl tyrosine phosphorylation, no activation of the abl kinase as measured by autophosphorylation, and a normal-size abl transcript suggest an alternative mechanism for leukemogenesis to that operative in Ph positive BCR/ABL positive chronic myeloid leukemia. A number of genes potentially relevant to tumorigenesis, some involving the ras signaling pathway, map to the 4p16 and 15q24 chromosome regions.