Li-Fraumeni syndrome is caused by a genetic alteration, a mutation, in a gene called TP53. This gene has a key role in controlling cell growth and tumor development. It determines the fate of cells and initiates a repair process or self-destruction for cells carrying damaged DNA and thus false genetic information material. If this important gene is defective, uncontrolled defective cells multiply and cancer develops.
Each person carries 2 copies of the TP53 gene, one copy from the mother and one copy from the father. With the LFS one of the two copies is damaged. If now also the 2nd still healthy copy of the TP53 gene is damaged, tumors develop.
The disease is transmitted via an autosomal dominant inheritance. That means every second child gets sick. About 70% of people with LFS have inherited the disease from their mother or father. In about 5-20% of cases, the mutation is newly spontaneous, which is called de novo.
Today it is assumed that about 1 out of 5000 people carries a mutation in the LFS gene. In some areas of Brazil there are many more people.