Short communication Molecular cytogenetic characterization of breakpoints in 19 patients with hematologic malignancies and 12p unbalanced translocations

Abstract Structural rearrangements of the short arm of chromosome 12 are frequent cytogenetic findings in various hematologic malignancies. The ETV6 gene is the most common target for rearrangements in 12p13. Fluor-escence in situ hybridization (FISH) investigations have shown that translocations of 12p other than t(12;21)are frequently accompanied by small interstitial deletions that include ETV6 . Unbalanced translocationsinvolving ETV6 have rarely been described, and breakpoints outside ETV6 appear to be strongly associ-ated with complex karyotypes. We studied bone marrow samples from 19 patients known to have 12p un-balanced translocations and complex karyotypes, using FISH and spectral karyotyping. FISH analysisconfirmed the hemizygous deletion of the ETV6 and CDKN1B genes in 74% of cases. We found fourcases with interstitial deletions. In these four cases and in two others (6/19, 31.5%), the fusion with thepartner chromosome was in the subtelomeric region of 12p13.3, confirming that there is a recurrent break- point in this region. © 2003 Elsevier Science Inc. All rights reserved.