MYCN and neoplasm: In addition to identifying novel mutations in MYCN, SMARCA4 and ARID1A, missense mutations were discovered in the miRNA processing enzymes DROSHA and DICER1. Further examination of tumour miRNA expression using in vitro processing assays and genomic editing of cell lines demonstrated that these mutations in DROSHA and DICER1 greatly influence miRNA processing and likely cause down regulation in mature miRNAs, which generate an altered miRNA expression profile in these WT patients.