Molecular diagnosis and minimal residual disease monitoring

Molecular analyses were performed at “La Sapienza” University of Rome, Italy. Total RNA was extracted from BM samples using the TRizol reagent or the Qiagen extraction kit. A reverse transcriptase multiplex polymerase chain reaction (RT-PCR-multiplex)³¹ was performed to detect the p190 or p210 forms of the BCR-ABL1 fusion product within the 7-day steroid pre-phase. Minimal residual disease (MRD) monitoring was performed by quantitative real-time PCR (Q-RT-PCR).^32,33 BCR-ABL1 transcript levels were normalized to the number of the ABL1 control gene and expressed as BCR-ABL1/ABL1 ×100; the level of BCR-ABL1 expression was then converted into a base 10 logarithmic scale. A complete molecular response was defined as a BCR-ABL1/ABL1 ratio equal to zero.