The object of this project is to apply results of recent advances in molecular biology, specifically molecular cloning of cellular oncogenes, synthesis of oncogene related peptides, and in situ chromosome hybridization to the diagnosis, evaluation, and monitoring of human leukemias--specifically to chronic myelogenous leukemia (CML). A novel 8 Kb RNA hybridizing with the normal, cellular homologue of the transforming gene of Abelson murine leukemia virus (c-abl) has been detected in patients with CML and the t(9,22) translocation (Ph' chromosome). It is not present in CML without the t(9,22) or other leukemias with rare exceptions. We will analyze patients with CML and related myeloproliferative disorders (Ph' negative CML) for this novel c-abl RNA. The objective is to define more precisely the Ph' negative leukemia and to correlate c-abl expression with disease phase and response to therapy. These RNA studies are to be complemented with analysis of c-abl related patients and by in situ chromosome hybridization using a v-abl probe. These studies will allow a more precise (molecular) definition of CML and related human leukemias. (6)