In a collaborative effort between DCEG, NHLBI, two centers in Brazil, and other international investigators, researchers are studying Li-Fraumeni syndrome (LFS) to identify the contribution of germline TP53 mutations to mitochondrial function, determine if abnormal mitochondrial function is a marker of cancer risk, and establish the role of telomere biology as a cancer risk modifier. A clinical research workshop on LFS was held at NIH in November 2010. Since then, collaborators have developed an international LFS research consortium and a patient advocacy group. Among the collaborators in the consortium are investigators from the Université de Rouen in France. A new clinical, genetic, and epidemiologic study of LFS at NIH has enrolled approximately 100 families, with another 60 eligible families in the process of being enrolled, and is evaluating a novel comprehensive cancer-screening strategy (including a total body MRI), molecular markers, genotype-phenotype correlations, and the psychological and social challenges faced by families with LFS.