Characterization of the 5q- breakpoint in an acute nonlymphocytic leukemia patient using pulsed-field gel electrophoresis.

Multiple genes of hematopoietic importance have been localized to the long arm of chromosome 5 including granulocytemacrophage colony stimulating factor (GM-CSF) and interleukins (IL) 3, 4 and 5 to 5q23-31, colony stimulating factor 1 (CSF1) to 5q33.1 and its receptor (c-fms) to 5q33.3. The genes coding for platelet-derived growth factor receptor (PDGFR) and acidic fibroblast growth factor (FGFA) have been localized to 5q31-32 and 5q31.3-33.2, respectively. These genes fall in the region of chromosome 5 which is deleted in the 5q- refractory anemia syndrome (5q-RA) and acute nonlymphocytic leukemia (ANLL). We have characterized this region in a 5q- patient with therapy-related ANLL (t-ANLL) by pulsed-field gel electrophoresis and Southern blotting analysis utilizing DNA probes for PDGFR, c-fms, and FGFA. A single 300 kbp M1uI restriction fragment was detected in the patient using a PDGFR probe as compared to a 200 kbp fragment in normal controls. BssHII digestions also showed restriction fragment length difference. Similar data for both M1uI and BssHII digestions were also obtained when c-fms was used as a probe. Southern blotting analysis of EcoRI-digested DNA showed that each of the PDGFR, c-fms, and FGFA alleles were deleted. These results suggested that one chromosome 5 has a large deletion involving PDGFR, c-fms and FGFA, which is consistent with the cytogenetic analysis of the patient. In contrast, the other chromosome 5, which appeared normal cytogenetically, may have a smaller deletion (or alteration) in proximity to but not involving any of these 3 genes.