Digital PCR

We are very pleased to be able to bring you this special issue of iomolecular Detection and Quantification which focuses on digital CR (dPCR). The underpinning method of dPCR, which was coined n 1999 [1], actually predates qPCR [2] and is a powerful technique hat could offer improved sensitivity, precision and reproducibility 3]. Now is an exciting time for this method and there are numerous xamples of where the improved reproducibility can be applied linically and where the superior sensitivity and precision could nable measurements to be performed that are simply not possible sing PCR or, in many cases, sequencing. In this special issue we have selected seven manuscripts that iscuss and present dPCR in a variety of subjects. Dhillon et al. resent a new application of dPCR in the form of a proximity ligaion assay (PLA) opening the possibility of using limiting dilution to mprove the detection and quantification of proteins which, in this ase focussed on Clostridium difficile toxins, are important markers or disease. Matthew Butchbach presents a review on the appliation of dPCR as a robust method to identify genes associated ith paediatric-onset disorders. This review also highlights how PCR can offer a powerful technology to track changes in genomic iomarkers with disease progression. He also argues that dPCR has he potential to become the tool of choice for the verification of utations identified by next generation sequencing, copy number etermination and also for non-invasive prenatal screening. The next four manuscripts deal with the application and analysis PCR. Whale et al. discuss multiplexing by dPCR and describe the ifferent approaches that can be applied highlighting the unique pproaches on offer by dPCR. They also report and name a characeristic of dPCR, namely partition specific competition (PSC), that ust be considered when applying thresholds to multiplex assays hat use the same primers but different probes, as is common when easuring single nucleotide variants or polymorphisms. Debski nd Garstecki describe how to design dPCR experiments to ensure esired precision is achieved when dealing with patient samples. his is an important and frequently neglected consideration when iscussing the performance of any molecular method. Jones and olleagues present a short report that investigates the dynamic ange of dPCR, which is often reported as being at a disadvantage hen compared with qPCR. In this study they demonstrate that if ou have enough partitions it is possible to perform dPCR with a ynamic range of up to six orders of magnitude, which is approachng that of qPCR. Finally the manuscript by Madic et al. describes pplication of the first three colour dPCR instrument for multiplex nalysis of three mutations of the EGFR gene. This droplet-based latform applies a unique sample partition format by employing a