Patients with NB appear to have high levels of cfDNA at diagnosis, of which a high proportion is tumour derived, i.e. ctDNA [94,101], and reports have demonstrated the detection of numerous genomic alterations, including MNA [80,95,97,101–110], ALK mutation [111], 11q deletion [80,95,110,112], 17q gain [80,110,113], and gene methylation [114] in cfDNA of patients with NB at various stages of the clinical course. This evidence concerns the gene ALK and neuroblastoma.