MYCN and neuroblastoma: According to the basic clinical stratification, paediatric oncologists distinguish two groups of neuroblastoma at diagnosis, the optimal age cutoff being 18 months (Cohn et al, 2009) The low-risk group consists of non-MYCN-amplified tumours that occur either as localised forms (stage 1, 2 and 3) or as metastatic forms in the children of age <18 months (stage 4 and 4S).