What causes LFS?
Li Fraumeni Syndrome is caused by a gene mutation in the p53 tumor suppressor gene. Most people with LFS have a genetic mutation that is passed on from a parent. Occasionally, LFS can result from a new gene mutation (de novo) without having parents affected or a family history of cancer. Not all families with LFS have a p53 gene mutation. There are many types of p53 gene mutations, which can behave differently in every person and within each family. Some families with LFS have very high rates of cancer incidence, while others don’t. The degree to which a p53 gene mutation causes cancer in a family or person is termed “penetrance.”
The p53 gene can function a little bit or not at all depending on the type of mutation to the area of the gene. Every cell has 2 copies of a gene, one from the person’s mother and one from the father. The mutated form of p53 is dominant, which means if you have a normal copy of the gene and a mutated form of the gene, you will see the effects of the mutated gene, in this case—a higher risk of developing cancer. If you have 2 normal genes, you will not see the effects. If someone with the gene mutation has children, then they have a 50% chance of passing along the gene mutation to their children. If you do not have the gene mutation, you will not pass along the effects to your children.
Cancers associated with LFS include adrenocortical cancer, brain tumors, soft tissue sarcomas, osteosarcomas, rhabdomyosarcoma, breast cancer, leukemia, lymphoma and glioblastoma. There are numerous other cancers that have been seen in LFS families, often occurring at younger ages than expected. Patients with LFS should seek input from healthcare providers experienced in caring for patients with Li-Fraumeni Syndrome.