JAK2V617F Analysis Shows Similar Results in Either Peripheral Blood (PB) or Bone Marrow (BM).
Rong He, Rebecca F McClure, Curtis A Hanson. Mayo Clinic, Rochester, MN
Background: Detection of JAK2V617F has become a necessary diagnostic assay in evaluating possible myeloproliferative neoplasms (MPNs). In clinical practice, it is not uncommon to see requests for JAK2V617F testing on both PB and BM samples from the same patient. To establish cost-effective hematopathology ancillary testing guidelines, we reviewed the JAK2V617F test results from our institution over the past 3 years, and identified patients with tests done on both PB and BM. The results were then compared. We hypothesized that PB and BM samples from the same patient would give similar results and that only one specimen is needed for diagnostic purposes.
Design: JAK2V617F analysis was performed using quantitative real-time PCR (qRT-PCR) with relative quantification and calibrator normalization. The assay is sensitive to at least 0.01% mutated DNA and interpreted as positive using a lab-determined cut-off. All JAK2V617F tests performed on our patients from 2006 to 2009 were reviewed (n=1624). 267 patients with concurrent PB and BM studies were identified. In the rare discrepant cases, clinical history, BM biopsy and aspirate, as well qRT-PCR histograms were reviewed.
Results: We identified 267 patients who had both PB and BM tested for JAK2V617F. 137 of these patients had concordant positive test results and 126 had concordant negative results. Only 4 patients showed discrepant results between the two samples: 2 with positive BM/negative PB and 2 with positive PB/negative BM. Review of the qRT-PCR tracings of the 4 negative discrepant cases demonstrated very low mutation burdens just below the normal cutoff value while qRT-PCR tracings of the 4 positive discrepant cases showed a very low level positivity just above the normal cut-off value. The BM diagnoses in the 4 discrepant cases included 1 MDS/MPN (unclassified) and 3 BMs without features of any myeloid malignancy. Finding either a low-level positive or a negative JAK2V617F result would have had no impact on clinical management or outcome of these 4 patients.
Conclusions: 1) Evaluation of PB and BM almost always (98.5%) gives concordant results for JAK2V617F analysis. 2) Only rarely (1.5%) do PB and BM give discrepant results. These are seen exclusively in cases with very low mutation burden. In no instance did this discrepancy affect the diagnosis and assessment of the associated BM specimen. 3) In clinical practice, JAK2V617F mutation analysis in both PB and BM is redundant and should be avoided. Clinical laboratories need to set up processes to eliminate duplicate PB/BM testing for JAK2V617F.
Tuesday, March 1, 2011 1:00 PM
Poster Session IV # 168, Tuesday Afternoon