Droplet digital PCR is a cost‐effective method for analyzing long cell‐free DNA in maternal plasma: Application in preeclampsia

Abstract

AbstractObjectiveLong cell‐free DNA (cfDNA) can be found in the plasma of pregnant women and cancer patients. We investigated if droplet digital PCR (ddPCR) can analyze such molecules for diagnostic purposes using preeclampsia as a model.MethodPlasma samples from ten preeclamptic and sixteen normal pregnancies were analyzed. Two ddPCR assays targeting a single‐copy gene, VCP, and one ddPCR assay targeting LINE‐1 repetitive regions were used to measure the percentages of long cfDNA >533, 1001, and 170 bp, respectively. The LINE‐1 assay was developed as guided by in silico PCR analyses to better differentiate preeclamptic and normal pregnancies.ResultsPreeclamptic patients had a significantly lower median percentage of long cfDNA than healthy pregnant controls, as determined by the LINE‐1 170 bp assay (28.9% vs. 35.1%, p < 0.0001) and the VCP 533 bp assay (6.6% vs. 8.7%, p = 0.014). The LINE‐1 assay provided a better differentiation than the VCP 533 bp assay (area under ROC curves, 0.94 vs. 0.79).ConclusionddPCR is a cost‐effective approach for unlocking diagnostic information carried by long cfDNA in plasma and may have applications for the detection of preeclampsia. Further longitudinal studies with larger cohorts are required to assess the clinical utility of this test.