FOXO1 gene belongs to the forkhead family of transcription factors which are characterized by a distinct forkhead domain. The specific function of this gene has not yet been determined; however, it may play a role in myogenic growth and differentiation. Translocations involving the FOXO1 (forkhead box O1) gene at 13q14.1 and either the PAX3 (paired box 3) gene at 2q36.1 or the PAX7 (paired box 7) gene at 1p36.1 are seen frequently in cases of alveolar rhabdomyosarcoma. Rhabdomyosarcoma is the most common soft-tissue sarcoma seen in children and younger adults with two major histological subtypes: alveolar rhabdomyosarcoma (ARMS) and embryonal rhabdomyosarcoma (ERMS). FOXO1 rearrangements are recognised recurrent abnormalities seen in ARMS, but not seen in ERMS. Most (75%) ARMS cases display recurrent chromosomal translocation that fuses two transcription factor-encoding genes together; the PAX3 gene (in a minority of cases the PAX7 gene) and the FOXO1 gene.