MYCN and neuroblastoma: Our observations suggest that the toxicity conferred by Cas9D10A is unlikely to be caused by changes in target locus copy number or gene expression level, as the observed changes for MYCN were relatively modest in Cas9D10A-treated MYCN-amplified neuroblastoma cell lines relative to the distribution of MYCN-amplification levels across different neuroblastoma cell lines tested in our experiments.