JAK2 V617F mutation can be reliably detected in serum using droplet digital PCR

Digital PCR: A Reliable Tool for Analyzing and Monitoring Hematologic Malignancies

The digital polymerase chain reaction (dPCR) is considered to be the third-generation polymerase chain reaction (PCR), as it yields direct, absolute and precise measures of target sequences. dPCR has proven particularly useful for the accurate detection and quantification of low-abundance nucleic acids, highlighting its advantages in cancer diagnosis and in predicting recurrence and monitoring minimal residual disease, mostly coupled with next generation sequencing. In the last few years, a series of studies have employed dPCR for the analysis of hematologic malignancies. In this review, we will summarize these findings, attempting to focus on the potential future perspectives of the application of this promising technology.

Serum Has Higher Proportion of Janus Kinase 2 V617F Mutation Compared to Paired EDTA-Whole Blood Sample: A Model for Somatic Mutation Quantification Using qPCR and the 2-∆∆Cq Method

Detection of the Janus Kinase-2 (JAK2) V617F mutation is a diagnostic criterion for myeloproliferative neoplasms, and high levels of mutant alleles are associated with worse outcomes. This mutation is usually tested on blood DNA by allele-specific qPCR (AS-qPCR) and measured using absolute quantification. However, some automated DNA extractions co-extracts of PCR inhibitors from blood and qPCR absolute quantification need increased efforts in order to maintain standard curves. JAK2 V617F can also be detected in serum using droplet digital PCR (ddPCR), a specimen with less inhibitors and favorable to automated extractions, but ddPCR instruments are not wide available as qPCR thermocyclers. Here, we evaluate whether JAK2 V617F could be accurately quantified by AS-qPCR using the 2-∆∆Cq method on blood DNA and validate the assay using gold-standard molecular diagnostic protocols. Next, we apply the validated method to assess if the mutation could be reliably detected/quantified in serum. JAK2 V617F could be quantified by AS-qPCR using the 2-∆∆Cq method-the assay was highly accurate (bias of 1.91%) compared to a commercial kit, highly precise (total CV% of 0.40%, 1.92%, 11.12% for samples with 93%, 54%, and 2.5% of mutant allele), highly sensitive (limit of detection of 0.15%), and demonstrated a linear detection response from 1.1% to 99.9%. Serum presented a higher mutant allele burden compared to the paired whole blood (mean of 4%), which allows for an increased JAK2 mutant detection rate and favors increased JAK2 V617F high-throughput analysis.

Superiority of Droplet Digital PCR Over Real-Time Quantitative PCR for JAK2 V617F Allele Mutational Burden Assessment in Myeloproliferative Neoplasms: A Retrospective Study

JAK2V617F mutational status is an essential diagnostic index in myeloproliferative neoplasms (MPNs). Although widely used for detection of JAK2 V617F mutation in peripheral blood (PB), sensitive real-time quantitative PCR (qPCR) presents some methodological limitations. Recently, emerging alternative technologies, like digital droplet PCR (ddPCR), have been reported to overcome some of qPCR’s technical drawbacks. The purpose of this study was to compare the diagnostic utility of ddPCR to qPCR for JAK2 V617F detection and quantification in samples from MPNs patients. Sensitivity and specificity of qPCR and ddPCR in the detection of the mutation were assessed by using a calibrator panel of mutated DNA on 195 JAK2 positive MPN samples. Based on our results, ddPCR proved to be a suitable, precise, and sensitive method for detection and quantification of the JAK2 V617F mutation.

Detection of small numbers of iPSCs in different heterogeneous cell mixtures with highly sensitive droplet digital PCR

Induced pluripotent stem cells (iPS cells) are a prospective resource for regenerative biomedicine. iPS cells can differentiate into any type of stem, progenitor and somatic cells to help replace structures within damaged organs or tissues. However, iPS cells themselves, can produce malignant tumors if they are injected into the body of an immunocompatible or immunodeficient recipient. Thus, it is necessary to detect any residual iPS cells content in biomedical cell products obtained from iPS cells and destined for transplantation. In this article we describe searches for iPS cells in heterogeneous cell mixtures, using two different methods-quantitative RT-PCR and droplet digital PCR (ddPCR). In experiments with various heterogeneous mixtures, including mixtures with neural stem cells, we found that the OCT4, TDGF1 and LIN28 genes are the best markers for such a search, and droplet digital PCR provides the greatest measurement accuracy, which is 0.002%. Thus, we have confirmed the advantage of using droplet digital PCR in the search for pluripotent stem cells in heterogeneous cell mixtures. We hope that this data can be useful for biosafety control in regenerative biomedicine.