Abstract
Background and objective: Accurate quantification of BCR-ABL mRNA is of critical importance for managing chronic myeloid leukemia (CML) patients receiving Imatinib therapy. RNA degradation thus constitutes a potential problem for laboratories quantifying minimal residual disease (MRD). Patient samples with long transport times between the hospital and the analyzing laboratory may be subject to RNA degradation with a corresponding loss in sensitivity and possible generation of false negative results. Recently, RNA preservation systems have been developed in order to improve RNA stability.
Design and methods: The aim of the study was to investigate the performance of the PAXgene Blood RNA Kit in CML follow-up peripheral blood samples and compared the results to unstabilized parallel Trizol extracted samples. The different sample processing methods were evaluated by real-time PCR.
Results: RNA isolated with the PAXgene system gave a superior yield per ml blood than with the routine Trizol extraction method. However, although of comparable quality, the RNA did not PCR-amplify as efficiently compared to equal amounts of RNA from routinely processed samples. Therefore, RNA processed with the PAXgene system showed to decreased sensitivity for MRD detection, resulting in false negatives. The sensitivity was comparable to samples processed routinely 20–30 hours after phlebotomy.
Interpretation and conclusions: We conclude that routinely processed, i.e. unstabilized, peripheral blood that reaches the laboratory and is processed within 30 hours is preferable for MRD detection. Optimal results were achieved with fresh samples processed within 5 hours with the Trizol method. However, RNA stabilization may be useful if sample transit is expected to exceed 30 hours.
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