Detection of minimal residual disease in leukaemia by RT-PCR.

Reverse transcription-PCR (RT-PCR) describes a technique whereby RNA is first reverse transcribed into complementary DNA (cDNA) using the enzyme reverse transcriptase, and the resulting cDNA amplified in either a single-step or a two-step nested PCR reaction. It is particularly useful for detecting molecular markers associated with leukaemia, as it enables a single assay to be used for many patients, each with unique genomic translocation breakpoints, but who have common fusion points in mRNA. This molecular method can not only detect aberrations that are cytogenetically cryptic, such as t(12;21)(p13;q22) in paediatric acute lymphoblastic leukaemia (ALL), but is also very sensitive, and as such can be used to monitor minimal residual disease (MRD). Detecting and measuring MRD is important because it can be a guide to determining prognosis and relapse risk, predict recurrence of leukaemia, and enable individualization of treatment.