A novel BCR-ABL fusion gene (e6a2) in a patient with Philadelphia chromosome-negative chronic myelogenous leukemia.
A novel variant of the chimeric BCR-ABL mRNA transcript was detected in a patient with Philadelphia chromosome-negative (Ph-) chronic myelogenous leukemia (CML) by multiplex reverse-transcription polymerase chain reaction (RT-PCR). Sequence analysis of the fusion region of the amplified cDNA fragment showed an in-frame joining of exon e6 of the BCR gene and exon a2 of the ABL gene, giving rise to an e6a2 BCR-ABL transcript. This finding was confirmed by Southern blot analysis using a specific probe corresponding to intron 6 of the BCR gene, whereas conventional Southern blot for rearrangement of the major breakpoint cluster region (M-bcr) was negative. Western blot studies detected a BCR-ABL protein slightly larger than p185 BCR-ABL. Metaphase fluorescence in situ hybridization showed an insertion of ABL material into the BCR region without reciprocal BCR translocation. The findings in this case show that atypical BCR-ABL transcripts are detectable even in Ph- CML patients without M-bcr-rearrangements. Multiplex PCR using primers that allow for amplification of all known BCR-ABL transcripts is an appropriate method to exclude these rare variants.
Hochhaus
A
A
III. Medizinische Klinik, Klinikum Mannheim der Universität Heidelberg, Mannheim, Germany.
Reiter
A
A
Skladny
H
H
Melo
J V
JV
Sick
C
C
Berger
U
U
Guo
J Q
JQ
Arlinghaus
R B
RB
Hehlmann
R
R
Goldman
J M
JM
Cross
N C
NC
D000328:Adult; D001483:Base Sequence; D002874:Chromosome Mapping; D017931:DNA Primers / Q000737:chemistry; D016044:Fusion Proteins, bcr-abl / Q000235:genetics*; D016313:Genes, abl; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000235:genetics*; D054438:Leukemia, Myeloid, Chronic, Atypical, BCR-ABL Negative / Q000235:genetics*; D008297:Male; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D014178:Translocation, Genetic
D017931:DNA Primers; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D016044:Fusion Proteins, bcr-abl