Korean J Clin Pathol.  1999 Aug;19(4):369-374.

Analysis of Breakpoints of bcr-abl Fusion Gene Using RT-PCR

• Shin S
• Park SS
• Cho HI
• Hur M
• Lee YJ

Abstract

BACKGROUND
Three types of chimeric mRNA can be expressed as a result of fusion of abl gene on chromosome 9 and bcr gene on chromosome 22. These are b3a2, b2a2, and e1a2. Rearranged mRNA of bcr-abl fusion gene is found in majority of chronic myelogenous leukemia (CML) and in 20% of acute lymphoblastic leukemia (ALL) and in other hematologic malignancies.
METHODS
We have examined the chimeric mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR) since 1994. Positive results for the chimeric mRNA were 167 (118 patients) out of 714 examined cases. 94 patients with CML irrespective of the disease course, 49 with ALL, 120 with acute myelogenous leukemia, 11 with acute mixed leukemia, and 7 with myelodysplastic syndrome were included.
RESULTS
97.9% (92/94) of patients with CML, 40% (20/49) of ALL, 45% (5/11) of acute mixed leukemia, and 14% (1/7) of myelodysplastic syndrome were positive for bcr-abl rearrangement. In CML, positive cases were with b3a2 (64%), b2a2 (32.6%), and b3a2/b2a2 (2.2%). One patient with CML-like feature expressed e1a2 type mRNA. In adult ALL, 62.5% (10/16) expressed minor-bcr (e1a2).
CONCLUSIONS
The bcr-abl fusion gene was positive in various hematologic diseases as well as CML and that fact indicates the dysfunction of primitive pleuripotent stem cells. Various expressions and changes of mRNA types in bcr-abl fusion gene might be due to alternative splicing mechanism and detection sensitivity of RT-PCR when two types were intermingled. We should be aware of these facts when interpretating the results.

Keyword

Bcr-abl fusion gene; Chronic myelogenous leukemia (CML); Reverse transcriptase-polymerease chain reaction (RT-PCR)

MeSH Terms

Adult
Alternative Splicing
Chromosomes, Human, Pair 22
Chromosomes, Human, Pair 9
Genes, abl
Hematologic Diseases
Hematologic Neoplasms
Humans
Leukemia
Leukemia, Myelogenous, Chronic, BCR-ABL Positive
Leukemia, Myeloid, Acute
Myelodysplastic Syndromes
Precursor Cell Lymphoblastic Leukemia-Lymphoma
RNA, Messenger
Stem Cells
RNA, Messenger