ddPCR of the RNA markers (both neuroblastoma-specific and cell cycle) and DNA markers from 200 μL of each SEC fraction from two other patients with metastatic disease (one (NBL2196) being PHOX2B-positive in unfractionated plasma and one PHOX2B-negative (NBL2187)) showed that the mRNA markers were mostly present in the EV-enriched fractions, whereas the DNA targets were mostly present in the higher, protein-enriched fractions (Figure 3A,B,D,E, Supplemental Table S11). This evidence concerns the gene PHOX2B and neuroblastoma.