Interpretation of ambiguous TP53 test results: Mosaicism, clonal hematopoiesis, and variants of uncertain significance

The increased use of next-generation sequencing has led to the detection of pathogenic TP53 variants in the germline setting in patients without a personal or family history consistent with Li-Fraumeni syndrome (LFS). These variants can represent low-penetrance LFS, mosaic LFS, or clonal hematopoiesis of indeterminate potential. Additionally, TP53 variants of uncertain significance can be detected in patients with a history suspicious for LFS. The interpretation of the significance of these variants can be challenging but is crucial for an accurate diagnosis and appropriate medical management. This retrospective case review provides illustrative examples of the interpretation of challenging TP53 results through multidisciplinary expertise and use of a flowchart. The authors describe eight patients with TP53 variants associated with ambiguous diagnoses and, for each case, describe how the results were interpreted and the medical care that was implemented. This report presents illustrative cases to help guide clinicians to reach definitive diagnoses for patients when confronted with TP53 variants that are inconsistent with the clinical picture and to add to the body of literature regarding interpretation and medical management of TP53 variants discovered on germline testing.