Bartley, P.Ross, D.Latham, S.Martin-Harris, M.Budgen, B.Wilczek, V.Branford, S.Hughes, T.Morley, A.2011-05-232011-05-232010International Journal of Laboratory Hematology, 2010; 32(6 Part 1):E222-E2281751-55211751-553Xhttp://hdl.handle.net/2440/63823Increasing numbers of patients with chronic myeloid leukaemia (CML) treated with tyrosine kinase inhibitors achieve undetectable levels of BCR-ABL mRNA using sensitive quantitative real-time reverse transcriptase PCR (RT-qPCR) methods and a method to measure minimal residual disease (MRD) in patients with low levels could be of value. Following isolation and sequencing of the patient-specific BCR-ABL breakpoint, a DNA-based nested qPCR assay was established, and MRD was measured by this method and one-round RT-qPCR in 38 samples from 24 patients with CML. Mixing experiments using patient DNA in normal DNA indicated that DNA qPCR could detect BCR-ABL sequences at a limit of approximately 10⁻⁶. In 22 samples in which MRD was detectable by both methods, comparison of the results of DNA qPCR with the results obtained on the same sample by RT-qPCR showed good correlation. In another 16 samples, BCR-ABL mRNA was not detectable by RT-qPCR. In 8 of the 16 samples, BCR-ABL DNA was detected at levels ranging from 1.1 × 10⁻⁵ up to 2.8 × 10⁻⁴ and in the remaining eight samples BCR-ABL was not detected by either method. In one patient, who had stopped imatinib, an almost 1000-fold rise in MRD, to 5.2 × 10⁻⁴ was observed in sequential samples. Nested DNA qPCR was more sensitive than one-round RT-qPCR and could be used for the monitoring of patients with CML with very low levels of MRD.en© 2010 Blackwell Publishing Ltd.Minimal residual diseasechronic myeloid leukaemiaBCR-ABLPCRmonitoringJournal article002010118710.1111/j.1751-553X.2010.01236.x0002835955000052-s2.0-7834929824233087Ross, D. [0000-0001-7171-2935]Branford, S. [0000-0002-1964-3626] [0000-0002-5095-7981]Hughes, T. [0000-0002-0910-3730] [0000-0002-7990-4509]