PAX3 and alveolar rhabdomyosarcoma: Rhabdomyosarcoma (RMS) is the most common STS in children and adolescents; alveolar rhabdomyosarcomas (ARMS) are characterized by either PAX3-FOXO1 or PAX7-FOXO1 fusion genes; ARMS with the former fusion most often carry additional 12q13-q14 amplifications, therefore including the CDK4 gene, which has been correlated with poor survival outcomes (68).