BM qRT-PCR is not clinically useful as a predictor of molecular relapse. Seven patients had detectable BCR-ABL mRNA in BM on at least one occasion while PB monitoring indicated stable UMRD. Samples with no detectable BCR-ABL are shown as open circles, and positive samples are shown as solid circles. Molecular relapse is denoted by “R” at the end of the timeline. The BM qRT-PCR indicated imminent molecular relapse in only 2 patients.