In addition to c-fos which has been associated with osteosarcoma formation due to its contribution in osteoblast differentiation [54, 55], some genetic predispositions have been linked with osteosarcoma development in hereditary syndromes such as Li-Fraumeni (p53 mutation) [56], Rothmund-Thompson [57], Werner [58] or Bloom syndromes (mutations of helicase genes) [59, 60], or retinoblastoma familial cancers [61]. The gene discussed is FOS; the disease is osteosarcoma.