Droplet digital PCR for quantification of PML-RARα in acute promyelocytic leukemia: a comprehensive comparison with real-time PCR

Real-time quantitative PCR (qPCR) has been widely implemented for molecular testing, but there are still some inherent limitations that hamper its usefulness. Droplet digital PCR (ddPCR), which can provide direct, standards-free quantification, has recently received increasing attention. In our study, a comprehensive comparison of ddPCR with qPCR in relation to the quantification of PML-RARα was performed to evaluate the diagnostic potential of ddPCR. Results showed that ddPCR displayed significant concordance with qPCR in the detection of PML-RARα in clinical samples, but showed advantages over qPCR in terms of precision, limit of detection (LOD), and other basic performance parameters. A study of the feasibility of duplexing also indicated that ddPCR could simultaneously quantify the target PML-RARα and the clinical common reference gene ABL in a reaction, in contrast to qPCR. Moreover, ddPCR was more tolerant than qPCR of inhibition, and was shown to be able to quantify inhibition-prone samples. Another advantage of using ddPCR in clinical applications is that it will yield accurate results for patients with PML-RARα levels that fluctuate around the LOD of qPCR. Therefore, ddPCR is considered to have the potential to become a reliable alternative technique for quantifying PML-RARα.