Despite extensive work understanding the altered molecular characteristics of PAX3-FOXO1 relative to PAX3 [19–25] and the knowledge that phosphorylation of the fusion protein contributes to ARMS tumor phenotypes [26], it is not known what role, if any, the fusion protein plays in the promotion of aneuploidy and chromosomal structural abnormalities, overcoming aneuploidy-dependent proliferative defects, and whether phosphorylation of the fusion protein contributes to this process. The gene discussed is PAX3; the disease is neoplasm.