Based on our amplicon boundary analysis, two classes of MYCN amplicons could be distinguished in neuroblastoma: (i) amplicons containing local MYCN-specific enhancers, including e4 (here referred to as class I amplicons; Fig. 3a) and (ii) amplicons lacking local MYCN-specific enhancers, and at least lacking e4 (referred to as class II amplicons; Fig. 3b). The gene discussed is MYCN; the disease is neuroblastoma.