Fig. 3

Cell-free DNA analysis of GLA and KLA patients. a Gene multiplexing on a droplet digital polymerase chain reaction (ddPCR) system using probes that target specific NRAS mutation in cell-free DNA isolated from plasma and pleural effusion samples (P1). NRAS mutation detection assays were performed using the mutation detection assay NRAS p.Q61R c.182A > G (Bio-Rad) in a ddPCR apparatus (QX200™ AutoDG™ Droplet Digital™ PCR system; Bio-Rad). Two fluorescence amplitude bands were clearly generated for each gene (upper band: NRAS Q61R mutant, lower band: NRAS wild type). b The data are expressed as a percentage of mutant droplets relative to the sum of wild-type droplets of each sample (P1–8, positive control and negative control). Positive controls included wild-type DNA. Negative control did not include DNA. Data are shown as the median and 95% confidence interval. The identities of the samples are as follows: P1–1: plasma sample of P1, P1–2: PE sample of P1, P2–1: plasma sample of P2, P2–2: PE sample of P2, P2–3: FFPE sample of P2, P3–1: plasma sample of P3, P3–2: PE sample of P3, P4–8: plasma sample of P4–8, PC: plasma sample of PC, NC: plasma sample of NC. WT: wild type, PE: pleural effusion, PC: positive control, NC: negative control