HETEROGENEITY IN THE BREAKPOINTS IN BALANCED REARRANGEMENTS INVOLVINGBAND 12P13 IN HEMATOLOGIC MALIGNANCIES IDENTIFIED BY FLUORESCENCE IN-SITU HYBRIDIZATION - TEL (ETV6) IS INVOLVED IN ONLY ONE HALF

Using fluorescence in situ hybridization (FISH) and probes located on 12p12.1 to 13.3, we studied the breakpoints of 23 patients who had var ious hematologic malignant diseases and who had 12p13-balanced translo cations (21 patients), inversion (1 patient), or insertion (1 patient) . Among them, 14 patients had breakpoints within YAC964c10. which cont ains the TEL (ETV6) gene and in 12 of these with balanced translocatio ns or insertion, the FISH results suggested that TEL was involved. Two of the 14 patients, patients no. 13 and 14, had breakpoints in YAC 96 4C10 that were centromeric to TEL but telomeric to KIP1. In the other 9 patients whose breakpoints did not fall within the YAC, the breakpoi nts were found telomeric to the YAC in at least three different locati ons on distal 12p. These results indicated that TEL was involved in on ly half (12 of 23) of the patients with balanced 12p13 rearrangements and that there probably were several other breakpoint cluster regions on 12p13, suggesting that genes other than TEL were involved in these rearrangements. (C) 1997 by The American Society of Hematology.