Diversity of the clinical presentation of the MMR gene biallelic mutations

Gaëlle Bougeard, Laurence Olivier-Faivre, Stéphanie Baert-Desurmont, Julie Tinat, Cosette Martin, Emilie Bouvignies, Stéphanie Vasseur, Frédéric Huet, Gérard Couillault, Pierre Vabres, Florence Le Pessot, Caroline Chapusot, David Malka, Brigitte Bressac-De Paillerets, Mario Tosi, Thierry Frebourg

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Constitutional mismatch repair-deficiency, due to biallelic mutations of MMR genes, results in a tumour spectrum characterized by leukaemias, lymphomas, brain tumours and adenocarcinomas of the gastro-intestinal tract, occurring mostly in childhood. We report here two families illustrating the phenotypic diversity associated with biallelic MMR mutations. In the first family, two siblings developed six malignancies including glioblastoma, lymphoblastic T cell lymphoma, rectal and small bowel adenocarcinoma with onset as early as 6 years of age. We showed that this dramatic clinical presentation was due to the presence of two complex genomic PMS2 deletions in each patient predicted to result into complete PMS2 inactivation. In the second family, the index case presented with an early form of Lynch syndrome with colorectal adenocarcinomas at ages 17 and 20 years, and urinary tract tumours at the age of 25 years. We identified in this patient two MSH6 mutations corresponding to a frameshift deletion and an in frame deletion. The latter was not predicted to result into complete inactivation of MSH6. These reports show that the clinical expression of biallelic MMR mutations depends on the biological impact of the second MMR mutation and that, in clinical practice, the presence of a second MMR mutation located in trans should also be considered in patients suspected to present a Lynch syndrome with an unusual early-onset of tumours.

Original languageEnglish
Pages (from-to)131-135
Number of pages5
JournalFamilial Cancer
Volume13
Issue number1
DOIs
StatePublished - Mar 2014
Externally publishedYes

Bibliographical note

Funding Information:
Acknowledgments This work was supported by the INCa, the French National Cancer Institute.

Funding

Acknowledgments This work was supported by the INCa, the French National Cancer Institute.

FundersFunder number
Institut National du Cancer

    Keywords

    • MMR
    • Mutation
    • Tumour

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