Li-Fraumeni syndrome (LFS) is an autosomal dominant disorder that predisposes individuals to multiple forms of cancer including breast carcinoma, soft tissue sarcoma, osteosarcoma, leukemia and adrenocortical carcinoma. These diverse tumor types develop at unusually early ages. Analysis of the tumor suppressor gene p53 in family members with LFS have demonstrated that germline mutations in the p53 gene were present in most of the LFS family tested so far. Furthermore, germline p53 mutations were also found in cancer-prone individuals which were not indicative of the LFS.