Instead, MRD detection in these cancers has focussed on the detection of tumour-specific messenger RNA (mRNA) using qRT-PCR of NB-specific RNA markers, such as TH and PHOX2B, or EWSR1 gene fusion transcripts with the ETS family or FLI1 gene for EWS-specific markers [33–36]. Here, EWSR1 is linked to cancer.