LETTERS TO JMG

Molecular basis of the Li–Fraumeni syndrome: an update from the French LFS families

G Bougeard¹, R Sesboüé¹, S Baert-Desurmont¹, S Vasseur¹, C Martin¹, J Tinat¹, L Brugières², A Chompret³, B Bressac-de Paillerets⁴, D Stoppa-Lyonnet⁵, C Bonaïti-Pellié⁶, T Frébourg, the French LFS working group¹

¹ Inserm U614, Faculty of Medicine, and Department of Genetics, University Hospital, Institute for Biomedical Research, Rouen, France
² Department of Pediatric Oncology, Institut Gustave Roussy, Villejuif, France
³ Department of Medicine, Institut Gustave Roussy, Villejuif, France
⁴ Department of Genetics, Institut Gustave Roussy, Villejuif, France
⁵ Department of Genetics, Institut Curie, Paris, France
⁶ Inserm U535, Villejuif, France

Dr T Frébourg, Inserm U614, Faculty of Medicine, 22 Boulevard Gambetta, 76183 Rouen, France; Frebourg{at}chu-rouen.fr

We have performed an extensive analysis of TP53 in 474 French families suggestive of Li–Fraumeni syndrome (LFS), including 232 families fulfilling the Chompret criteria. We identified a germline alteration of TP53 in 82 families (17%), in 67/232 of the families fulfilling the Chompret criteria (29%) and in 15/242 which did not fulfil these criteria (6%). Most of the alterations corresponded to missense mutations (67%), and we identified in four families genomic deletions removing the entire TP53 locus, the promoter and the non-coding exon 1, or exons 2–10. These results represent a definitive argument demonstrating that LFS results from TP53 haplodeficiency. The mean ages of tumour onset were significantly different between patients harbouring TP53 missense mutations and other types of alterations, missense mutations being associated with a 9 year earlier tumour onset. These results confirm that missense mutations not only inactivate p53 but also have an additional oncogenic effect. Germline alterations of TP53 that lead exclusively to loss of function are therefore associated with a later age of tumour onset and the presence of such mutations should be considered in atypical LFS families with tumours diagnosed after 40 years.

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• Tinat, J., Bougeard, G., Baert-Desurmont, S., Vasseur, S., Martin, C., Bouvignies, E., Caron, O., Bressac-de Paillerets, B., Berthet, P., Dugast, C., Bonaiti-Pellie, C., Stoppa-Lyonnet, D., Frebourg, T. (2009). 2009 Version of the Chompret Criteria for Li Fraumeni Syndrome. JCO 27: e108-e109 [Full Text]  
• Gonzalez, K. D.F., Buzin, C. H., Weitzel, J. N., Sommer, S. S. (2009). Reply to J. Tinat et al. JCO 27: e110-e110 [Full Text]