DESCRIPTION (Applicant's Description): The TEL-PDGFBR fusion protein was identified as the protein product of a t(5;12) translocation in a patient with chronic myelomonocytic leukemia (CMML). The protein fuses the amino portion of TEL with the transmembrane and cytoplasmic domains of the PDGFBR. TEL, a member of the ETS family of transcription factors, has subsequently been described as a common site of rearrangement in multiple forms of leukemia. This is not yet the case for the PDGFBR. The applicants find, however, in the Preliminary Results, that another patient with CMML has a novel t(5;7) translocation. Southern blotting analysis has identified a breakpoint in this patient at the same genomic localization in the PDGFBR as the t(5;12) translocation. Their hypothesis is, that in this patient, as for the t(5;12) TEL-PDGFR patients, PDGFBR is constitutively activated by fusion with a 7q24 partner. Although rare (as for identification of TEL), the PDGFBR fusion partner at 7q24 may identify a gene involved in a broader group of malignancies. Also, in light of the facts that other patients with CMML have PDGFR containing fusions and the region of 7q24 is frequently deleted in MDS, the cloning, characterization and manipulation of this fusion protein is paramount. Hence, in Specific Aim 1, they will use anchored PCR to clone the breakpoint. Their specific oligos will come from the known PDGFBR sequence. In Specific Aim 2, they will obtain a full length cDNA and determine the relevance of this by performing ribonuclease protection assays and mapping back to chromosome 7. Finally, for Specific Aim 3 they propose to characterize the fusion protein by determining its transforming, activity(s) and biological properties using mutational and biochemical analyses.