Sorted By Test Name - Mayo Medical Laboratories

BA190
83336
BCRAB
89007
positive, the fusion variant is also reported.
Clinical References: Hochhaus A, Reiter A, Skladny H, et al: A novel BCR-ABL fusion gene
(e6a2) in a patient with Philadelphia chromosome-negative chronic myelogenous leukemia. Blood 1996
September 15;88(6):2236-2240
BCR/ABL, p190, mRNA Detection, Reverse Transcription-PCR
(RT-PCR), Quantitative, Monitoring Assay
Clinical Information: mRNA transcribed from BCR/ABL (fusion of the breakpoint cluster region
gene [BCR]at chromosome 22q11 to the Abelson gene [ABL] at chromosome 9q23) is detected in all
chronic myelogenous leukemia (CML) patients and a subset of both acute lymphoblastic leukemia (ALL)
and acute myeloid leukemia (AML) patients. Although breakpoints in the BCR and ABL genes may occur
in a variety of locations, splicing of the primary RNA transcripts result in only 8 fusion site variants
(e1/a2, e6/a2, e13/a2, e14/a2, e19/a2, and e1/a3, e13/a3, e14/a3), which incorporate the entire sequence of
the exons on both sides of the fusion site. The e1/a2 and e1/a3 fusion forms produce a 190-kDa protein
designated p190. This bcr/abl protein form is found in approximately 75% of childhood ALL patients and
approximately 50% of adult ALL patients, with the majority arising from e1/a2 mRNA. The p190 is also
the predominant fusion form in a small subset of CML patients, although the vast majority of CML cases
contain the p210 protein, typically from e13/a2 or e14/a2 mRNA fusions. Other fusion forms are very
rare. Quantitative reverse-transcription PCR (qRT-PCR) is the most sensitive method for monitoring
bcr/abl levels during treatment. This test detects mRNA coding for the most common p190 fusion form
(e1/a2).
Useful For: Monitoring response to therapy in patients with known e1/a2 bcr/abl (p190) fusion forms
Interpretation: An interpretive report will be provided.
Reference Values:
The presence or absence of the BCR/ABL mRNA (bcr/abl) fusion form producing the p190 fusion protein
is reported. If positive, the level is reported as the ratio of bcr/abl (p190) to abl with conversion to a
percentage (ie, bcr/abl (p190) as a percentage of total abl).
Clinical References: 1. Hughes TP, Kaeda J, Branford S, et al: Frequency of major molecular
responses to imatinib or interferon alfa plus cytarabine in newly diagnosed chronic myeloid leukemia. N
Engl J Med 2003;349:1423-1432 2. Radich JP, Gooley T, Bryant E, et al: The significance of BCR/ABL
molecular detection in chronic myeloid leukemia patients "late," 18 months or more after transplantation.
Blood 2001;98:1701-1707 3. Olavarria E, Kanfer E, Szydlo R, et al: Early detection of BCR-ABL
transcripts by quantitative reverse transcriptase-polymerase chain reaction predicts outcome after
allogeneic stem cell transplant for chronic myeloid leukemia. Blood 2001;97:1560-1565
BCR/ABL, p210, mRNA Detection, Reverse Transcription-PCR
(RT-PCR), Quantitative, Monitoring Chronic Myelogenous
Leukemia (CML)
Clinical Information: Chronic myelogenous leukemia (CML) is a hematopoietic stem cell neoplasm
included in the broader diagnostic category of myeloproliferative neoplasms. CML is consistently
associated with fusion of the breakpoint cluster region gene (BCR) at chromosome 22q11 to the Abelson
gene (ABL) at chromosome 9q23. This fusion is designated BCR/ABL and may be seen on routine
karyotype as the Philadelphia chromosome. Although various breakpoints within the BCR and ABL genes
have been described, >95% of CMLs contain mRNA in which either the BCR exon 13 (e13) or BCR exon
14 (e14) is fused to the ABL exon 2 (a2), yielding fusion forms e13/a2 and e14/a2, respectively. The
e13/a2 and e14/a2 fusion forms produce a 210-kDa protein (p210). The p210 fusion protein is an
abnormal tyrosine kinase known to be critical for the clinical and pathologic features of CML, and agents
that block the tyrosine kinase activity, such as imatinib, have been used successfully for treatment. It has
been shown that monitoring the level of BCR/ABL mRNA (bcr/abl) in CML patients during treatment is
Current as of January 4, 2013 7:15 pm CST 800-533-1710 or 507-266-5700 or MayoMedicalLaboratories.com Page 231