Dataset Information

Prevalence and Spectrum of Germline BRCA1 and BRCA2 Variants of Uncertain Significance in Breast/Ovarian Cancer: Mysterious Signals From the Genome.

ABSTRACT: About 10-20% of breast/ovarian (BC/OC) cancer patients undergoing germline BRCA1/2 genetic testing have been shown to harbor Variants of Uncertain Significance (VUSs). Since little is known about the prevalence of germline BRCA1/2 VUS in Southern Italy, our study aimed at describing the spectrum of these variants detected in BC/OC patients in order to improve the identification of potentially high-risk BRCA variants helpful in patient clinical management. Eight hundred and seventy-four BC or OC patients, enrolled from October 2016 to December 2020 at the "Sicilian Regional Center for the Prevention, Diagnosis and Treatment of Rare and Heredo-Familial Tumors" of University Hospital Policlinico "P. Giaccone" of Palermo, were genetically tested for germline BRCA1/2 variants through Next-Generation Sequencing analysis. The mutational screening showed that 639 (73.1%) out of 874 patients were BRCA-w.t., whereas 67 (7.7%) were carriers of germline BRCA1/2 VUSs, and 168 (19.2%) harbored germline BRCA1/2 pathogenic/likely pathogenic variants. Our analysis revealed the presence of 59 different VUSs detected in 67 patients, 46 of which were affected by BC and 21 by OC. Twenty-one (35.6%) out of 59 variants were located on BRCA1 gene, whereas 38 (64.4%) on BRCA2. We detected six alterations in BRCA1 and two in BRCA2 with unclear interpretation of clinical significance. Familial anamnesis of a patient harboring the BRCA1-c.3367G>T suggests for this variant a potential of pathogenicity, therefore it should be carefully investigated. Understanding clinical significance of germline BRCA1/2 VUS could improve, in future, the identification of potentially high-risk variants useful for clinical management of BC or OC patients and family members.

SUBMITTER: Fanale D

PROVIDER: S-EPMC8226162 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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Prevalence and Spectrum of Germline BRCA1 and BRCA2 Variants of Uncertain Significance in Breast/Ovarian Cancer: Mysterious Signals From the Genome.

Fanale Daniele D Fiorino Alessia A Incorvaia Lorena L Dimino Alessandra A Filorizzo Clarissa C Bono Marco M Cancelliere Daniela D Calò Valentina V Brando Chiara C Corsini Lidia Rita LR Sciacchitano Roberta R Magrin Luigi L Pivetti Alessia A Pedone Erika E Madonia Giorgio G Cucinella Alessandra A Badalamenti Giuseppe G Russo Antonio A Bazan Viviana V

Frontiers in oncology 20210611

About 10-20% of breast/ovarian (BC/OC) cancer patients undergoing germline BRCA1/2 genetic testing have been shown to harbor Variants of Uncertain Significance (VUSs). Since little is known about the prevalence of germline BRCA1/2 VUS in Southern Italy, our study aimed at describing the spectrum of these variants detected in BC/OC patients in order to improve the identification of potentially high-risk BRCA variants helpful in patient clinical management. Eight hundred and s ...[more]

PMID: 34178674

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Project description:Mutations in BRCA1 and BRCA2 are responsible for a large proportion of breast-ovarian cancer families. Protein-truncating mutations have been effectively used in the clinical management of familial breast cancer due to their deleterious impact on protein function. However, the majority of missense variants identified throughout the genes continue to pose an obstacle for predictive informative testing due to low frequency and lack of information on how they affect BRCA1/2 function. Phosphorylation of BRCA1 and BRCA2 play an important role in their function as regulators of DNA repair, transcription and cell cycle in response to DNA damage but whether missense variants of uncertain significance (VUS) are able to disrupt this important process is not known. Here we employed a novel approach using NetworKIN which predicts in vivo kinase-substrate relationship, and evolutionary conservation algorithms SIFT, PolyPhen and Align-GVGD. We evaluated whether 191 BRCA1 and 43 BRCA2 VUS from the Breast Cancer Information Core (BIC) database can functionally alter the consensus phosphorylation motifs and abolish kinase recognition and binding to sites known to be phosphorylated in vivo. Our results show that 13.09% (25/191) BRCA1 and 13.95% (6/43) BRCA2 VUS altered the phosphorylation of BRCA1 and BRCA2. We highlight six BRCA1 (K309T, S632N, S1143F, Q1144H, Q1281P, S1542C) and three BRCA2 (S196I, T207A, P3292L) VUS as potentially clinically significant. These occurred rarely (n<2 in BIC), mutated evolutionarily conserved residues and abolished kinase binding to motifs established in the literature involved in DNA repair, cell cycle regulation, transcription or response to DNA damage. Additionally in vivo phosphorylation sites identified via through-put methods are also affected by VUS and are attractive targets for studying their biological and functional significance. We propose that rare VUS affecting phosphorylation may be a novel and important mechanism for which BRCA1 and BRCA2 functions are disrupted in breast cancer.

Project description:A population-based series of 649 unselected incident cases of ovarian cancer diagnosed in Ontario, Canada, during 1995-96 was screened for germline mutations in BRCA1 and BRCA2. We specifically tested for 11 of the most commonly reported mutations in the two genes. Then, cases were assessed with the protein-truncation test (PTT) for exon 11 of BRCA1, with denaturing gradient gel electrophoresis for the remainder of BRCA1, and with PTT for exons 10 and 11 of BRCA2. No mutations were found in all 134 women with tumors of borderline histology. Among the 515 women with invasive cancers, we identified 60 mutations, 39 in BRCA1 and 21 in BRCA2. The total mutation frequency among women with invasive cancers, 11.7% (95% confidence interval [95%CI] 9.2%-14.8%), is higher than previous estimates. Hereditary ovarian cancers diagnosed at age <50 years were mostly (83%) due to BRCA1, whereas the majority (60%) of those diagnosed at age >60 years were due to BRCA2. Mutations were found in 19% of women reporting first-degree relatives with breast or ovarian cancer and in 6.5% of women with no affected first-degree relatives. Risks of ovarian, breast, and stomach cancers and leukemias/lymphomas were increased nine-, five-, six- and threefold, respectively, among first-degree relatives of cases carrying BRCA1 mutations, compared with relatives of noncarriers, and risk of colorectal cancer was increased threefold for relatives of cases carrying BRCA2 mutations. For carriers of BRCA1 mutations, the estimated penetrance by age 80 years was 36% for ovarian cancer and 68% for breast cancer. In breast-cancer risk for first-degree relatives, there was a strong trend according to mutation location along the coding sequence of BRCA1, with little evidence of increased risk for mutations in the 5' fifth, but 8.8-fold increased risk for mutations in the 3' fifth (95%CI 3.6-22.0), corresponding to a carrier penetrance of essentially 100%. Ovarian, colorectal, stomach, pancreatic, and prostate cancer occurred among first-degree relatives of carriers of BRCA2 mutations only when mutations were in the ovarian cancer-cluster region (OCCR) of exon 11, whereas an excess of breast cancer was seen when mutations were outside the OCCR. For cancers of all sites combined, the estimated penetrance of BRCA2 mutations was greater for males than for females, 53% versus 38%. Past studies may have underestimated the contribution of BRCA2 to ovarian cancer, because mutations in this gene cause predominantly late-onset cancer, and previous work has focused more on early-onset disease. If confirmed in future studies, the trend in breast-cancer penetrance, according to mutation location along the BRCA1 coding sequence, may have significant impact on treatment decisions for carriers of BRCA1-mutations. As well, BRCA2 mutations may prove to be a greater cause of cancer in male carriers than previously has been thought.

Project description:Background:The spectrum of BRCA mutations that predispose to development of breast/ovarian cancer in Indian population remains unexplored. We report incidence and various types of pathogenic, likely pathogenic and variants of unknown significance (VUS) mutations in BRCA1 and BRCA2 genes observed at a tertiary cancer center in North India. Materials and methods:A total of 206 unrelated breast and/or ovarian cancer patients, who met the National Comprehensive Cancer Network (NCCN) guidelines for genetic testing, were screened for germline BRCA1/BRCA 2 mutations on high-throughput sequencing platform; large genomic rearrangements were assessed by multiple ligation probe assay. Mutations were mined in mutational databases, PubMed, and discerned into classes. Furthermore, the clinicopathological correlation of BRCA mutation status with prognostic markers in breast cancer and tumor histology in ovarian cancer was performed. Results:In total, 45/206 and 17/206 cases showed positivity for BRCA1 and BRCA2 mutations, respectively, whereas 1/206 was positive for a mutation in both the genes. Altogether, 33 distinct BRCA1 mutations were observed, among which 27 were deleterious (12 frameshifts, 8 nonsense, 1 missense, 3 splice-site variants, 2 big deletions and 1 large duplication) and 6 were VUS. Five novel BRCA1 mutations (c.541G>T, c.1681delT, c.2295delG, c.4915C>T and exon 23 deletion) were identified. Seven mutations (c.2214_2215insT, c.2295delG, c.3607C>T,c.4158_4162delCTCTC, c.4571C>A, splicesite_3 (C>T) and exon 21-23 duplication) occurred more than once, whereas 16 distinct BRCA2 mutations were noted - 9 were lethal (6 frameshifts, 2 nonsense and 1 big deletion) and 7 VUS. One unique pathogenic BRCA2 mutation (c.932_933insT) was recognized. Two mutations (c.9976A>T and c.10089A>G) recurred twice. No significant difference in hormone receptor status was observed among BRCA1 carriers, BRCA2 carriers and noncarriers. Conclusion:We have documented various pathogenic and VUS mutations in BRCA1 and BRCA2 genes observed in the cohort. Six novel mutations were identified. The knowledge shared would assist genetic testing in enabling more focused site-specific screening for mutations in biological relatives.

Project description:BACKGROUND:BRCA1/2 germline mutation related cancers are candidates for new immune therapeutic interventions. This study was a hypothesis generating exploration of genomic data collected at diagnosis for 19 patients. The prominent tumor mutation burden (TMB) in hereditary breast and ovarian cancers in this cohort was not correlated with high global immune activity in their microenvironments. More information is needed about the relationship between genomic instability, phenotypes and immune microenvironments of these hereditary tumors in order to find appropriate markers of immune activity and the most effective anticancer immune strategies. METHODS:Mining and statistical analyses of the original DNA and RNA sequencing data and The Cancer Genome Atlas data were performed. To interpret the data, we have used published literature and web available resources such as Gene Ontology, The Cancer immunome Atlas and the Cancer Research Institute iAtlas. RESULTS:We found that BRCA1/2 germline related breast and ovarian cancers do not represent a unique phenotypic identity, but they express a range of phenotypes similar to sporadic cancers. All breast and ovarian BRCA1/2 related tumors are characterized by high homologous recombination deficiency (HRD) and low aneuploidy. Interestingly, all sporadic high grade serous ovarian cancers (HGSOC) and most of the subtypes of triple negative breast cancers (TNBC) also express a high degree of HRD. CONCLUSIONS:TMB is not associated with the magnitude of the immune response in hereditary BRCA1/2 related breast and ovarian cancers or in sporadic TNBC and sporadic HGSOC. Hereditary tumors express phenotypes as heterogenous as sporadic tumors with various degree of "BRCAness" and various characteristics of the immune microenvironments. The subtyping criteria developed for sporadic tumors can be applied for the classification of hereditary tumors and possibly also characterization of their immune microenvironment. A high HRD score may be a good candidate biomarker for response to platinum, and potentially PARP-inhibition. TRIAL REGISTRATION:Phase I Study of the Oral PI3kinase Inhibitor BKM120 or BYL719 and the Oral PARP Inhibitor Olaparib in Patients With Recurrent TNBC or HGSOC (NCT01623349), first posted on June 20, 2012. The design and the outcome of the clinical trial is not in the scope of this study.

Dataset Information

Prevalence and Spectrum of Germline BRCA1 and BRCA2 Variants of Uncertain Significance in Breast/Ovarian Cancer: Mysterious Signals From the Genome.

Publications

Prevalence and Spectrum of Germline <i>BRCA1</i> and <i>BRCA2</i> Variants of Uncertain Significance in Breast/Ovarian Cancer: Mysterious Signals From the Genome.

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