The TP53 gene provides instructions for making a protein called tumor protein p53, which acts as a tumor suppressor. It helps regulate the cell cycle and prevent cells from growing and dividing too rapidly or in an uncontrolled way. Mutations in the TP53 gene can lead to a loss or reduction of its tumor-suppressive function, allowing cells to grow and divide uncontrollably, which can contribute to the development of cancer.

TP53 mutations are commonly associated with various types of cancer, including Li-Fraumeni syndrome (LFS), thyroid cancer, Hypodiploid acute lymphocytic leukemia (ALL) and Chronic Lymphocytic Leukemia (CLL).

In thyroid cancer, TP53 mutations are more frequently found in anaplastic thyroid carcinoma (ATC), a rare but aggressive and highly malignant type of thyroid cancer. TP53 mutations are less common in well-differentiated thyroid cancers like papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC). When TP53 mutations are present in thyroid cancer, it often indicates a more advanced and aggressive disease with a poorer prognosis. Thyroid cancers with TP53 mutations may be less responsive to standard treatments, making the management of such cases more challenging.

Apart from thyroid cancers, TP53 testing is also commonly performed for CLL, where all individuals diagnosed with CLL undergo TP53 sequencing prior to the initiation of treatment, to direct the selection of appropriate therapy. TP53 alterations found in CLL have been shown to convey resistance to some standard chemotherapies such as fludarabine, cyclophosphamide and rituximab. TP53 mutation is also an independent marker of poor prognosis in individuals with CLL. Current guidelines recommend using TP53 mutation status as a tool to identify the most appropriate regimen for symptomatic CLL individuals requiring treatment