The defining oncogenic event in ARMS is a t(1;13) or t(2;13) chromosomal translocation in which the PAX7 or PAX3 DNA-binding domain, respectively, is fused to the FOXO1 transactivation domain to create a PAX3/7-FOXO1 chimeric oncogene (Barr et al., 1993; Galili et al., 1993; Shapiro et al., 1993; Davis et al., 1994). Here, PAX3 is linked to alveolar rhabdomyosarcoma.