An intermediate level of MYCN gain, estimated at 6 copies, was detected in the metastasis (Fig. 4h), indicating the initial 2p24 gain occurred early in tumour evolution, followed by additional 2p24 gains in the primary tumour and the metastasis, likely due to increased accumulation of MYCN in circular extrachromosomal DNA elements, as recently described39–41. Here, MYCN is linked to neoplasm.