A simple strategy for breakpoint fragment determination in chronic myeloidleukemia

Molecular characterization is considered a part of the routine work-up of c hronic myeloid leukemia (CML) cases. Southern blot analysis using the unive rsal BCR (UBCR) probe on BglII-digested DNA samples is the most commonly us ed technique, while employing the human 3' bcr probe (PR-1) is usually cons idered a complementary tool. In this study, we tried to develop a simple an d economic strategy for molecular characterization of Ch lt using the 3' pr obe as it has been shown to be the one capable of locating the breakpoint s ite. Seventy-eight cases of CML were studied. Molecular analysis was perfor med using the Southern blot technique. DNA was digested with Barn HI, Bg/II , EcoRI, and XbaI. Hybridization was performed using the human 3' bcr (PR-1 ) probe. BamHI and BglII could differentiate fragment 1 (F1) showing rearra ngement (R) with Barn HI and germline configuration (G) with BglII; F2/3 sh owing R with both, and F4 showing R with BamHI and G with BglII. F2/3 cases were further divided by HindIII enzyme into F2 showing (G) and F3 shouing (R). Fragment 0 showed G with both, but R with EcoRI and/or XbaI, while 3' deletion gave G with all four enzymes. Our results showed a relative incide nce of 6.4% for FB, 20.5% for F1. 32.1% for F2, 19.2% for F3, 15.4% For F4, and 6.4% for 3' deletion. Sixty cases were evaluated clinically and hemato logically and were followed up for disease evolution and survival. They inc luded 32 cases in early chronic phase, 24 in late chronic phase, two in acc eleration, and two in blastic crisis. No significant correlation was encoun tered between the breakpoint site and any of the clinical and hematological data except those patients with 3' deletion who showed a very short surviv al. The study emphasizes Southern blotting as the method of choice for mole cular characterization of CML and offers a simple and economic strategy for diagnosis and determination of breakpoint fragment. (C) 2000 Elsevier Scie nce Inc. All rights reserved.