This test detects only the e1/a2 bcr/abl (p190) fusion form. Other fusion forms are not detected by this assay, including those containing the BCR e13 and e14 exons, which code for the p210 protein commonly found in CML.
This test should not be used to monitor patients carrying bcr/abl fusion forms coding for the p210 protein, which includes most CML patients; #89007 "BCR/ABL p210, mRNA, Reverse Transcription-PCR (RT-PCR), Quantitative, Monitoring CML" should be ordered for this purpose.
This test should not be used to screen for bcr/abl fusions at the time of diagnosis; #89006, "BCR/ABL, mRNA, Detection, Reverse Transcription-PCR (RT-PCR), Qualitative, Diagnostic Assay" should be ordered for this purpose.
The precision of this assay at low bcr/abl levels is relatively poor, such that inter-run variation can be as high as 0.5 log. Only level changes >0.5 log should be considered clinically significant.
For example, if a result is given as 0.1% bcr/abl(p190):abl, then any result between 0.05% and 0.5% should be considered essentially equivalent. If the results are being used to make major therapeutic decisions, significant changes during monitoring should be verified with a subsequent specimen.
Results of this assay cannot be directly compared with results generated from other PCR assays, including identical assays performed in other laboratories. Monitoring should be performed using the same method and laboratory for each subsequent specimen.
The results of this assay cannot be directly compared with bcr/abl results obtained using FISH technology. FISH measures DNA alleles and this PCR-based assay measures mRNA transcripts. Because a single DNA allele can produce man mRNA transcripts, the values are not directly comparable.
Blood is the specimen of choice for monitoring. While most patients show similar bcr/abl levels in blood and bone marrow drawn at the same time, some patients have a consistent difference in the levels in blood and bone marrow such that altering specimen types during monitoring can lead to confusion.
Assay precision does not appear to be significantly affected by specimen transport or moderate delays in processing. However, in specimen with very low levels of bcr/abl, these conditions may cause sufficient RNA degradation to produce false-negative results. Thus, specimen should be shipped as quickly as possible and specimens >3 days old at the time of receipt will be considered unacceptable.