High-risk Breast Cancer Susceptibility Research Articles

Effectiveness and tasks of breast MRI surveillance for high-risk women with cancer susceptibility genes other than BRCA1/2: a single institution study.

In Japan, with the introduction of multigene panel testing, there is an urgent need to build a new medical system for hereditary breast cancer patients that covers pathogenic variants other than BRCA1/2. The aim of this study was to reveal the current status of breast MRI surveillance for high-risk breast cancer susceptibility genes other than BRCA1/2 and the characteristics of detected breast cancer. We retrospectively examined 42 breast MRI surveillance with contrast performed on patients with hereditary tumors other than BRCA1/2 pathogenic variants at our hospital from 2017 to 2021. MRI exams were evaluated independently by two radiologists. Final histopathological diagnosis for malignant lesions were obtained from surgical specimen. A total of 16 patients included TP53, CDH1, PALB2, ATM pathogenic variants and 3 variant of unknown significance. 2 patients with TP53 pathogenic variants were detected breast cancer by annual MRI surveillance. The rate of cancer detection was 12.5% (2/16). One patient was detected synchronous bilateral breast cancer and unilateral multiple breast cancers (3 lesions in 1 patient), so there were 4 malignant lesions in total. Surgical pathology of 4 lesions were 2 ductal carcinoma in situ, 1 invasive lobular carcinoma, and 1 invasive ductal carcinoma. MRI findings of 4 malignant lesions were detected as 2 non mass enhancement, 1 focus and 1 small mass. All of 2 patients with PALB2 pathogenic variants had previously developed breast cancer. Germline TP53 and PALB2 were strongly associated with breast cancer, suggesting that MRI surveillance is essential for breast cancer-related hereditary predisposition.

Epidemiological and ES cell-based functional evaluation of BRCA2 variants identified in families with breast cancer.

The discovery of high-risk breast cancer susceptibility genes, such as Breast cancer associated gene 1 (BRCA1) and Breast cancer associated gene 2 (BRCA2) has led to accurate identification of individuals for risk management and targeted therapy. The rapid decline in sequencing costs has tremendously increased the number of individuals who are undergoing genetic testing world-wide. However, given the significant differences in population-specific variants, interpreting the results of these tests can be challenging especially for novel genetic variants in understudied populations. Here we report the characterization of novel variants in the Malaysian and Singaporean population that consist of different ethnic groups (Malays, Chinese, Indian, and other indigenous groups). We have evaluated the functional significance of 14 BRCA2 variants of uncertain clinical significance by using multiple in silico prediction tools and examined their frequency in a cohort of 7840 breast cancer cases and 7928 healthy controls. In addition, we have used a mouse embryonic stem cell (mESC)-based functional assay to assess the impact of these variants on BRCA2 function. We found these variants to be functionally indistinguishable from wild-type BRCA2. These variants could fully rescue the lethality of Brca2-null mESCs and exhibited no sensitivity to six different DNA damaging agents including a poly ADP ribose polymerase inhibitor. Our findings strongly suggest that all 14 evaluated variants are functionally neutral. Our findings should be valuable in risk assessment of individuals carrying these variants.

Under-ascertainment of breast cancer susceptibility gene carriers in a cohort of New Zealand female breast cancer patients

BackgroundDiagnostic screening for pathogenic variants in breast cancer susceptibility genes, including BRCA1, BRCA2, PALB2, PTEN and TP53, may be offered to New Zealanders from suspected high-risk breast (and ovarian) cancer families. However, it is unknown how many high-risk pathogenic variant carriers in New Zealand are not offered genetic screening using existing triage tools and guidelines for breast (and ovarian) cancer patients.MethodsPanel-gene sequencing of the coding and non-coding regions of the BRCA1 and BRCA2 genes, and the coding regions and splice sites of CDH1, PALB2, PTEN and TP53, was undertaken for an unselected cohort of 367 female breast cancer patients. A total of 1685 variants were evaluated using the ENIGMA and the ACMG/AMP variant classification guidelines.ResultsOur study identified that 13 (3.5%) breast cancer patients carried a pathogenic or likely pathogenic variant in BRCA1, BRCA2, PALB2, or PTEN. A significantly higher number of pathogenic variant carriers had grade 3 tumours (10/13) when compared to non-carriers; however, no other clinicopathological characteristics were found to be significantly different between (likely) pathogenic variant carriers and non-carriers, nor between variant of unknown significance carriers and non-carriers. Notably, 46% of the identified (likely) pathogenic variant carriers had not been referred for a genetic assessment and consideration of genetic testing.ConclusionOur study shows a potential under-ascertainment of women carrying a (likely) pathogenic variant in a high-risk breast cancer susceptibility gene. These results suggest that further research into testing pathways for New Zealand breast cancer patients may be required to reduce the impact of hereditary cancer syndromes for these individuals and their families.

Abstract 2335: Heterozygous PALB2 mutations cause replication stress and DNA repair defects in carrier derived lymphoblastoid cell lines

Abstract During the last decade, PALB2 has been defined as a high-risk breast cancer susceptibility gene alongside BRCA1 and BRCA2. Heterozygous mutation in PALB2 increases the lifetime breast cancer risk of female carriers to an average of 53%, but the risk estimate is affected by family history, studied population, and the specific pathogenic variant. We have previously shown that lymphoblastoid cell lines (LCLs) of persons heterozygous for PALB2 c.1592delT, a Finnish founder mutation, show defects in DNA replication and damage response. Now we examine how various heterozygous, protein-truncating PALB2 founder mutations from different populations affect cell function, and whether the observed phenotype correlates with disease risk. The study cohorts come from Canada, Australia, and Finland and consist of 80 LCLs of PALB2 mutation carriers (c.1592delT, c.2323C>T, c.3113G>A or c.3323delA) and suitable population controls. There is some evidence that these variants are associated with different magnitudes of breast cancer risk, and PALB2 c.3113G>A has been associated with an exceptionally high cancer risk of 91% (95% CI 44-100) to age 70. Utilizing these LCLs, we have studied DNA damage response, cell cycle progression, and DNA replication with various methods. DNA fiber assay results show that PALB2 mutation carriers elongate their DNA more slowly during replication, likely due to increased fork stalling, but compensate this by increased dormant origin firing. The strongest replication phenotype was observed for PALB2 c.3113G>A carriers. High content analysis shows that most of the mutation carriers had compromised RAD51 foci formation after DNA damage, whereas 53BP1 foci levels were elevated. These results indicate that during DNA double-strand break repair, heterozygous PALB2 mutation carriers may rely more on alternative, error-prone pathways that are independent of RAD51, thus contributing to genomic instability. Additionally, we are currently performing RNA-Seq to determine if the LCLs show adaptation of their gene expression in response to pathogenic PALB2 variants. Citation Format: Niina Laurila, Kerstin Borgmann, Muthiah Bose, Felix Meyer, Katri Pylkäs, Bing Xia, William Foulkes, Melissa Southey, Helmut Pospiech, Robert Winqvist. Heterozygous PALB2 mutations cause replication stress and DNA repair defects in carrier derived lymphoblastoid cell lines [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2335.

Functional analysis of genetic variants in the high-risk breast cancer susceptibility gene PALB2

Heterozygous carriers of germ-line loss-of-function variants in the DNA repair gene PALB2 are at a highly increased lifetime risk for developing breast cancer. While truncating variants in PALB2 are known to increase cancer risk, the interpretation of missense variants of uncertain significance (VUS) is in its infancy. Here we describe the development of a relatively fast and easy cDNA-based system for the semi high-throughput functional analysis of 48 VUS in human PALB2. By assessing the ability of PALB2 VUS to rescue the DNA repair and checkpoint defects in Palb2 knockout mouse embryonic stem (mES) cells, we identify various VUS in PALB2 that impair its function. Three VUS in the coiled-coil domain of PALB2 abrogate the interaction with BRCA1, whereas several VUS in the WD40 domain dramatically reduce protein stability. Thus, our functional assays identify damaging VUS in PALB2 that may increase cancer risk.

Twenty Years of BRCA1 and BRCA2 Molecular Analysis at MMCI - Current Developments for the Classification of Variants.

Deleterious mutations in the BRCA1 and BRCA2 genes account for a considerable proportion of dominantly inherited breast and ovarian cancer susceptibility. The laboratory interpretation has always been dependent on the information available at the time of the report conclusion. The aim of this study has been to review the results from the BRCA testing at Masaryk Memorial Cancer Institute (MMCI). Patients with suspected hereditary predisposition to breast/ovarian cancer, belonging to 7,400 families, were referred by genetic counsellors for BRCA1 and BRCA2 mutation testing at the MMCI from 1999 to the beginning of 2018. Various methods have been used over 20 years of laboratory practice - starting with the Protein Truncation Test and Heteroduplex Analysis via the High Resolution Melting analysis and Sanger sequencing up to Next Generation Sequencing. BRCA1 and BRCA2 mutation screening resulted in the identification of 1,021 families with a germline high-risk BRCA1 mutation and 497 families carrying a high-risk BRCA2 mutation, representing a mutation detection rate of 20.5%. A broad spectrum of unique mutations classified as pathogenic or likely pathogenic has been detected in both genes - 124 in the BRCA1 and 123 in the BRCA2 gene. Other sequence variants (96 unique variants in the BRCA1 and 126 in the BRCA2 gene) have been revised and classified as benign or likely benign. The other 82 unique variants remain classified as of uncertain significance mainly due to a lack of information for inclusion in other groups. All the results are summarised in the tables, including the reasons for their classification. The clinical classification of rare sequence variants identified in the high-risk breast cancer susceptibility genes BRCA1 and BRCA2 is essential for appropriate genetic counselling. Here we present an overview of BRCA mutation frequencies in our region and the retrospective evaluation and eventually reclassification of previously reported rare variants in light of recent findings.

Nasledni karcinom dojke i jajnika - genetičko testiranje u Srbiji

Breast cancer makes up 25% of all new cancers in women globally. Even though it usually occurs by chance (sporadic breast cancer), 5-10% of all breast cancer cases belong to hereditary breast cancer. It is usually characterized by many cancer cases (breast and/or ovarian), earlier age of onset, multiple primary and bilateral or multifocal cancers. Up to 30% of hereditary breast and ovarian cancers harbor a mutation in high risk breast cancer susceptibility genes BRCA1 or BRCA2. Besides BRCA genes, there are also other genes with the smaller effect on the risk. Since May 2016, 161 patients have been tested for the presence of mutations in the 19-gene panel at the Institute for Oncology and Radiology of Serbia. The majority of the mutations were in BRCA1 (15/161), BRCA2 (7/161) and PALB2 (7/161). Pathogenic mutations were also detected in ATM (2/161), CHEK2 (4/161) and TP53 (1/161). Variants of unclassified significance (VUS) were detected in BRCA2 (6/161), ATM (5/161), PMS2 (6/161), NBN (5/161) and PALB2 (5/161). 25 family members were tested for particular family mutation using targeted Sanger sequencing. Additional 6 mutations were detected in BRCA1, 1 in BRCA2, 3 in PALB2, 1 in CHEK2 and 1 in ATM gene. New sequencing technology lowered the cost of genetic testing and enabled higher access to genetic testing and genetic counseling for middle and lower-income countries. Our results of multi-gene germline testing showed the importance of widening the spectrum of the genes that should be offered for detecting hereditary predisposition in Serbia.

Germline RECQL mutations are associated with breast cancer susceptibility.

Several moderate- and high-risk breast cancer susceptibility genes have been discovered, but more are likely to exist. To discover new breast cancer susceptibility genes, we used 2 populations (from Poland and Quebec, Canada) and applied whole-exome sequencing in a discovery phase (n = 195), followed by validation. We identified rare recurrent RECQL mutations in each population. In Quebec, 7 of 1,013 higher-risk breast cancer cases and 1 of 7,136 newborns carried the c.634C>T (p.Arg215*) variant (P = 0.00004). In Poland, 30 of 13,136 unselected breast cancer cases and 2 of 4,702 controls carried the c.1667_1667+3delAGTA (p.K555delinsMYKLIHYSFR) variant (P = 0.008). RECQL is implicated in resolving stalled DNA replication forks to prevent double-stranded DNA (dsDNA) breaks. This function is related to that of other known breast cancer susceptibility genes, many of which are involved in repairing dsDNA breaks. We conclude that RECQL is a breast cancer susceptibility gene.

Journeys into the genome of cancer cells

I come from a family in which there have been no scientists or doctors. I was interested, however, in biology at school and started my scientific career by training in medicine at Oxford University and Guys Hospital, London. Practising as a doctor reinforced my curiosity about the biological processes underlying human disease. As a consequence, I pursued a clinical vocation in histopathology, a discipline that couples exposure to the sights and smells of the autopsy room with a daily journey into the often beautiful, sometimes ugly world of healthy and diseased human tissues under the microscope. After an introduction to general histopathology in Nick Wright's department at the Hammersmith Hospital, London, I completed my postgraduate medical training in neuropathology with Peter Lantos at the Maudsley Hospital, London.Peering at the nuclei of cancer cells under the microscope, for me it was a matter of fascination that hidden within them were the key events converting normal cells into cancer cells, and frustration because they were out of reach. Many of the tissue samples examined by pathologists are from cancers. The clonal theory of cancer development and the general role of DNA mutations in generating cancer cell clones had been established by 1986 when I was working as a junior pathologist. Indeed, the first mutated cancer gene, HRAS , had recently been identified through application of the, then new, technologies of recombinant DNA technology. Peering at the nuclei of cancer cells under the microscope, for me it was a matter of fascination that hidden within them were the key events converting normal cells into cancer cells, and frustration because they were out of reach. So, I took 3 years break from medicine to study for a PhD, learning the methods and thinking of molecular oncology in Colin Cooper's laboratory at the Institute …

The application of nonsense-mediated mRNA decay inhibition to the identification of breast cancer susceptibility genes

BackgroundIdentification of novel, highly penetrant, breast cancer susceptibility genes will require the application of additional strategies beyond that of traditional linkage and candidate gene approaches. Approximately one-third of inherited genetic diseases, including breast cancer susceptibility, are caused by frameshift or nonsense mutations that truncate the protein product [1]. Transcripts harbouring premature termination codons are selectively and rapidly degraded by the nonsense-mediated mRNA decay (NMD) pathway. Blocking the NMD pathway in any given cell will stabilise these mutant transcripts, which can then be detected using gene expression microarrays. This technique, known as gene identification by nonsense-mediated mRNA decay inhibition (GINI), has proved successful in identifying sporadic nonsense mutations involved in many different cancer types. However, the approach has not yet been applied to identify germline mutations involved in breast cancer. We therefore attempted to use GINI on lymphoblastoid cell lines (LCLs) from multiple-case, non- BRCA1/2 breast cancer families in order to identify additional high-risk breast cancer susceptibility genes.MethodsWe applied GINI to a total of 24 LCLs, established from breast-cancer affected and unaffected women from three multiple-case non-BRCA1/2 breast cancer families. We then used Illumina gene expression microarrays to identify transcripts stabilised by the NMD inhibition.ResultsThe expression profiling identified a total of eight candidate genes from these three families. One gene, PPARGC1A, was a candidate in two separate families. We performed semi-quantitative real-time reverse transcriptase PCR of all candidate genes but only PPARGC1A showed successful validation by being stabilised in individuals with breast cancer but not in many unaffected members of the same family. Sanger sequencing of all coding and splice site regions of PPARGC1A did not reveal any protein truncating mutations. Haplotype analysis using short tandem repeat microsatellite markers did not indicate the presence of a haplotype around PPARGC1A which segregated with disease in the family.ConclusionsThe application of the GINI method to LCLs to identify transcripts harbouring germline truncating mutations is challenging due to a number of factors related to cell type, microarray sensitivity and variations in NMD efficiency.