Plant genetic effects on microbial hubs impact host fitness in repeated field trials.

Although complex interactions between hosts and microbial associates are increasingly well documented, we still know little about how and why hosts shape microbial communities in nature. In addition, host genetic effects on microbial communities vary widely depending on the environment, obscuring conclusions about which microbes are impacted and which plant functions are important. We characterized the leaf microbiota of 200 Arabidopsis thaliana genotypes in eight field experiments and detected consistent host effects on specific, broadly distributed microbial species (operational taxonomic unit [OTUs]). Host genetic effects disproportionately influenced central ecological hubs, with heritability of particular OTUs declining with their distance from the nearest hub within the microbial network. These host effects could reflect either OTUs preferentially associating with specific genotypes or differential microbial success within them. Host genetics associated with microbial hubs explained over 10% of the variation in lifetime seed production among host genotypes across sites and years. We successfully cultured one of these microbial hubs and demonstrated its growth-promoting effects on plants in sterile conditions. Finally, genome-wide association mapping identified many putatively causal genes with small effects on the relative abundance of microbial hubs across sites and years, and these genes were enriched for those involved in the synthesis of specialized metabolites, auxins, and the immune system. Using untargeted metabolomics, we corroborate the consistent association between variation in specialized metabolites and microbial hubs across field sites. Together, our results reveal that host genetic variation impacts the microbial communities in consistent ways across environments and that these effects contribute to fitness variation among host genotypes.

Safety of the Breast Cancer Adjuvant Radiotherapy in Ataxia-Telangiectasia Mutated Variant Carriers.

The Ataxia-Telangiectasia Mutated (ATM) gene is implicated in DNA double-strand break repair. Controversies in clinical radiosensitivity remain known for monoallelic carriers of the ATM pathogenic variant (PV). An evaluation of the single-nucleotide polymorphism (SNP) rs1801516 (G-A) showed different results regarding late subcutaneous fibrosis after breast radiation therapy (RT). The main objective of this study was to evaluate acute and late toxicities in carriers of a rare ATM PV or predicted PV and in carriers of minor allele A of rs1801516 facing breast RT. Fifty women with localized breast cancer treated with adjuvant RT between 2000 and 2014 at Institut Curie were selected. Acute and late toxicities in carriers of a rare PV or predicted PV (n= 9), in noncarriers (n = 41) and in carriers of SNP rs1801516 (G-A) (n = 8), were examined. The median age at diagnosis was 53 years old and 82% of patients had an invasive ductal carcinoma and 84% were at clinical stage I-IIB. With a median follow-up of 13 years, no significant difference between carriers and noncarriers was found for acute toxicities (p > 0.05). The same results were observed for late toxicities without an effect from the rs1801516 genotype on toxicities. No significant difference in acute or late toxicities was observed between rare ATM variant carriers and noncarriers after breast RT for localized breast cancer.

Familial uveal melanoma and other tumors in 25 families with monoallelic germline MBD4 variants.

BACKGROUND: Monoallelic germline MBD4 pathogenic variants were recently reported to cause a predisposition to uveal melanoma, associated with a specific tumor mutational signature and good response to immunotherapy. Monoallelic tumor pathogenic variants have also been described in brain tumors, breast cancers, and myxofibrosarcomas, whereas biallelic germline MBD4 pathogenic variants have been involved in a recessive hereditary adenomatous polyposis and a specific type of acute myeloid leukemia. METHODS: We analyzed MBD4 for all patients with a diagnosis of uveal melanoma at Institut Curie since July 2021 and in the 3240 consecutive female probands explored at the Institut Curie for suspicion of predisposition to breast cancer between July 2021 and February 2023. RESULTS: We describe 25 families whose probands carry a monoallelic germline pathogenic variant in MBD4. Eighteen of these families presented with uveal melanoma (including a case patient with multiple uveal melanoma), and 7 families presented with breast cancer. Family histories showed the first familial case of uveal melanoma in monoallelic MBD4 pathogenic variant carriers and other various types of cancers in relatives, especially breast, renal, and colorectal tumors. CONCLUSIONS: Monoallelic MBD4 pathogenic variant may explain some cases of familial and multiple uveal melanoma as well as various cancer types, expanding the tumor spectrum of this predisposition. Further genetic testing in relatives combined with molecular tumor analyses will help define the tumor spectrum and estimate each tumor's risk.

Prevalent versus incident breast cancers: benefits of clinical and radiological monitoring in women with pathogenic BRCA1/2 variants.

Women with pathogenic germline BRCA1 or BRCA2 variants have a higher risk of breast cancer than in the general population. International guidelines recommend specific clinical and radiological breast follow-up. This specific breast screening program has already been shown to be of clinical benefit, but no information is available concerning the use of prognostic factors or specific survival to guide follow-up decisions. We evaluated "high-risk" screening in a retrospective single-center study of 520 women carrying pathogenic germline variants of the BRCA1 or BRCA2 gene treated for breast cancer between January 2000 and December 2016. We compared two groups of women: the incidental breast cancer group (IBCG) were followed before breast cancer diagnosis (N = 103), whereas the prevalent breast cancer group (PBCG) (N = 417) had no specific follow-up for high risk before breast cancer diagnosis. Breast cancers were diagnosed at an earlier stage in the IBCG than in the PBCG: T0 in 64% versus 19% of tumors, (p < 0.00001), and N0 in 90% vs. 75% (p < 0.00001), respectively. Treatment differed significantly between the 2 groups: less neoadjuvant chemotherapy (7.1% vs. 28.5%, p < 0.00001), adjuvant chemotherapy (47.7% vs. 61.9%, p = 0.004) and more mastectomies (60% vs. 42% p < 0.0001) in the IBCG vs PBCG groups respectively. Overall and breast cancer-specific mortality were similar between the two groups. However, the patients in the IBCG had a significantly longer metastasis-free survival than those in the PBCG, at three years (96.9% [95% CI 93.5-100] vs. 92.30% [95% CI 89.8-94.9]; p = 0.02), suggesting a possible long-term survival advantage.

[Constitutional MMR deficiency: Genetic bases and clinical implications]. / Syndrome CMMRD (déficience constitutionnelle des gènes MMR) : bases génétiques et aspects cliniques.

Inherited mono-allelic mutation in one of the 4 major MMR genes results in Lynch syndrome which predisposes, in adulthood, mainly to colorectal and endometrial tumors characterized by microsatellite instability (MSI phenotype). Individuals with bi-allelic mutations of one of these genes developed early and multiple malignancies, most often in childhood. This recessively inherited condition is named CMMRD for Constitutional Mismatch Repair Deficiency. The spectrum of tumors is distinct from Lynch syndrome. Malignant brain tumors are at least as frequent as gastrointestinal tumors and in more than a third of cases haematological malignancies were also reported. Patients also displayed clinical features similar of neurofibromatosis type 1, especially café au lait spots. The most commonly involved genes are PMS2 and MSH6 while bi-allelic MLH1 and MSH2 mutations are rare. The digestive tumors of these patients show MSI whereas the brain tumors can be "microsatellite stable". Because of variable clinical presentation and phenotypical overlaps with other cancer syndromes, CMMRD syndrome is frequently unrecognized by clinicians and its incidence is almost certainly underestimated. A better knowledge of clinical criteria and diagnosis methods should improve the identification of these patients at least at the time when they develop their first tumor or even before. This will allow adjusting treatment modalities and offering surveillance strategies of other tumor risks, not only for patients themselves but also for their relatives.

Hereditary breast and ovarian cancer: successful systematic implementation of a group approach to genetic counselling.

The increase in referrals to cancer genetics clinics, partially associated with the "Angelina Jolie effect", presents a challenge to existing services, many are already running at full capacity. More efficient ways to deliver genetic counselling are therefore urgently needed. We now systematically offer group instead of standard individual counselling to patients with suspected Hereditary Breast and Ovarian Cancer. Group sessions last 30 min. The first twenty consist of a presentation by the genetic counsellor, the next ten of a discussion involving a cancer geneticist and a psychologist. A short individual consultation ensues, where personal and family issues are addressed and consent obtained. Blood is drawn afterwards. Satisfaction and knowledge are evaluated. We report data for the Oct-2014-Aug-2015 period. 210 patients attended group counselling, up to eight simultaneously. We always fitted them within a 4-h time frame. Mean satisfaction score was 41/43. Knowledge scores increased from 3.1/6 to 4.9/6 post-counselling (p value < 2.2 × 10-16). Thanks to group counselling, we have withstood increases in referrals without compromising care. The "Angelina Jolie effect" and rapid developments in personalized medicine threaten to overwhelm cancer genetics clinics. In this context, our innovative approach should ensure that all patients have access to approved services.