J Clin Pathol Qual Control.  1997 Dec;19(2):261-271.

Hematological Significance of Southern Blot Test for bcr-abl Rearrangement and the Breakpoints within Major bcr in Chronic Myelogenous Leukemia

• Park SS
• Lee YK
• Cho SI
• Cho HI

Abstract

BACKGROUND: Bcr-abl rearrangement is the molecular hallmark of chronic myelogenous leukemia, of which analysis is the standard test for the diagnosis of chronic myelogenous leukemia (CML). Southern blot analysis is a basic diagnostic method of bcr-abl rearrangement to be able to prevent the contamination in polymerase chain reaction (PCR), but still the clinical significance of breakpoint location within the bcr is uncertain. We analyzed hematological significance of Southern blot test for bcr-abl rearrangement and the breakpoints within the bcr in CML.
METHODS
Objectives were 343 cases (135 cases with CML, 40 with acute lymphoblastic leukemia (ALL), and 168 with other hematologic diseases) to test bcr-abl rearrangement since 1991. Bcr-abl rearrangements were analyzed using two genomic probe (5' and/or 3' probe) and three restriction endonucleases (BglII, BamHI and HindIII), Five breakpoint zones (I-V) within the bcr were determined in the 57 patients with CML according to the Southern blot results.
RESULTS
Eighty nine percent of cases with clinically diagnosed CML were bcr-abl positive. Bcr-abl rearrangement was positive in 28 of 30 cases with Philadelphia positive CML, and negative in all of five Philadelphia negative cases. In ALL 12.5% (5/40) was bcr-abl positive, and in other hematologic diseases 5 cases (3.0%) were positive (two cases with AML, one with acute biphenotypic leukemia, two with chronic myeloproliferative disorders). Breakpoint distribution of 57 CML patients were 24.6% (14 cases) in breakpoint zone II, 29.8% (17) in III, 42.1% (24) in IV and 3.5% (2) in V. Those cases reclassified as 54.4% (31 patients) in 5' region (II+III) and 45.6% (26) in 3' region (IV+V). In the correlative analysis of the hematological parameters and breakpoint locations, only the histologic classification was significant : mixed type (granulo-/megakaryocytic type) had higher frequency in 3' breakpoint region than granulocytic type.
CONCLUSIONS
Southern blot test is basic and reliable method to detect bcr-abl rearrangement. We observed the relationship between histologic type of CML and breakpoint region within the bcr, which might be a basic mechanism to explain the increased thrombopoietic activity in CML with 3' site breakpoint reported by other researchers.

MeSH Terms

Blotting, Southern*
Classification
Diagnosis
DNA Restriction Enzymes
Hematologic Diseases
Humans
Leukemia, Biphenotypic, Acute
Leukemia, Myelogenous, Chronic, BCR-ABL Positive*
Polymerase Chain Reaction
Precursor Cell Lymphoblastic Leukemia-Lymphoma
DNA Restriction Enzymes