Transit of Samples to the Laboratory

A key issue in the provision of reliable laboratory results relates to sample collection procedures and transit time to the laboratory. Heparin can potentially interfere with PCR, and blood or bone marrow samples are more appropriately collected in ED TA. For assays that involve PCR amplification of genomic DNA, for example, detection of FLT3 ITD/D835, relatively prolonged transit times (i.e., 3 to 7 days) are unlikely to be particularly problematic. However, for RNA-based assays, quantitative RT-PCR has revealed degradation equivalent to approximately 0.5 log per 24 hours. Appropriate quantitation of fusion transcripts is feasible if endogenous control transcripts with a comparable degradation rate are amplified in parallel. However, it is important to bear in mind that the control transcript will not correct for the loss in sensitivity resulting from prolonged transit time. Hence there is interest in the development of RNA-stabilizing agents that reduce RNA degradation during specimen transit; these have been most extensively evaluated in MRD monitoring in chronic myeloid leukemia.

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