The two primary subtypes of RMS encountered in the pediatric population, ERMS and ARMS, can be distinguished molecularly as nearly 85% of ARMS are defined by gene fusions between PAX3-FOXO1 or PAX7-FOXO11, whereas ERMS are characterized by disparate mutations in the RAS pathway, effectors of the PI3 Kinase pathway, or in genes that control the cell cycle2. Here, PAX7 is linked to alveolar rhabdomyosarcoma.