The Frequency of Germline BRCA and Non-BRCA HR-Gene-Variants in a Cohort of Pancreatic Cancer Patients.

Germline DNA alterations affecting homologous recombination pathway genes have been associated with pancreatic cancer (PC) risk. BRCA2 is the most studied gene and affects the management of PC patients and their families. Even though recent reports have suggested a similar role of germline ATM pathogenic variants (PV) in familial PC, there is still a disagreement between experts on how it could affect patient management given the lack of proper PC risk estimates. We retrospectively analyzed the germline data of 257 PC patients among whom nearly 50% were sporadic cases. We showed similar frequencies of BRCA2 (4.9%) and ATM (4.4%) PV or likely pathogenic variants, which were not related to familial history. Based on our findings and that of the literature, we suggest including ATM gene among the panel of genes analyzed in PC patients pending the publication of prospective studies.

Increased incidence of pathogenic variants in ATM in the context of testing for breast and ovarian cancer predisposition.

Pathogenic Variants (PV) in major cancer predisposition genes are only identified in approximately 10% of patients with Hereditary Breast and Ovarian Cancer (HBOC) syndrome. Next Generation Sequencing (NGS) leads to the characterization of incidental variants in genes other than those known to be associated with HBOC syndrome. The aim of this study was to determine if such incidental PV were specific to a phenotype. The detection rates of HBOC-associated and incidental PV in 1812 patients who underwent genetic testing were compared with rates in control groups FLOSSIES and ExAC. The rates of incidental PV in the PALB2, ATM and CHEK2 genes were significantly increased in the HBOC group compared to controls with, respective odds ratios of 15.2 (95% CI = 5.6-47.6), 9.6 (95% CI = 4.8-19.6) and 2.7 (95% CI = 1.3-5.5). Unsupervised Hierarchical Clustering on Principle Components characterized 3 clusters: by HBOC (P = 0.01); by ExAC and FLOSSIES (P = 0.01 and 0.02 respectively); and by HBOC, ExAC and FLOSSIES (P = 0.01, 0.04 and 0.04 respectively). Interestingly, PALB2 and ATM were grouped in the same statistical cluster defined by the HBOC group, whereas CHEK2 was in a different cluster. We identified co-occurrences of PV in ATM and BRCA genes and confirmed the Manchester Scoring System as a reliable PV predictor tool for BRCA genes but not for ATM or PALB2. This study demonstrates that ATM PV, and to a lesser extent CHEK2 PV, are associated with HBOC syndrome. The co-occurrence of ATM PV with BRCA PV suggests that such ATM variants are not sufficient alone to induce cancer, supporting a multigenism hypothesis.

Constitutional mismatch repair deficiency syndrome: clinical description in a French cohort.

BACKGROUND: Constitutional mismatch repair deficiency (CMMRD) syndrome is a childhood cancer predisposition syndrome involving biallelic germline mutations of MMR genes, poorly recognised by clinicians so far. METHODS: Retrospective review of all 31 patients with CMMRD diagnosed in French genetics laboratories in order to describe the characteristics, treatment and outcome of the malignancies and biological diagnostic data. RESULTS: 67 tumours were diagnosed in 31 patients, 25 (37%) Lynch syndrome-associated malignancies, 22 (33%) brain tumours, 17 (25%) haematological malignancies and 3 (5%) sarcomas. The median age of onset of the first tumour was 6.9 years (1.2-33.5). Overall, 22 patients died, 9 (41%) due to the primary tumour. Median survival after the diagnosis of the primary tumour was 27 months (0.26-213.2). Failure rate seemed to be higher than expected especially for T-cell non-Hodgkin's lymphoma (progression/relapse in 6/12 patients). A familial history of Lynch syndrome was identified in 6/23 families, and consanguinity in 9/23 families. PMS2 mutations (n=18) were more frequent than other mutations (MSH6 (n=6), MLH1 (n=4) and MSH2 (n=3)). CONCLUSIONS: In conclusion, this unselected series of patients confirms the extreme severity of this syndrome with a high mortality rate mostly related to multiple childhood cancers, and highlights the need for its early detection in order to adapt treatment and surveillance.

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

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.