Accordingly, NB patients were divided into two groups on the basis of (i) MYCN amplification (single copy versus amplified), (ii) BM infiltration (not infiltrated versus infiltrated), (iii) age at diagnosis (<18 months versus >18 months), (iv) stage of the disease (stages 1-2 versus stages 3-4), and (v) sex (male versus female). Here, MYCN is linked to neuroblastoma.