Cancer predisposing missense and protein truncating BARD1 mutations in non‐BRCA1 or BRCA2 breast cancer families

Fifteen years ago BRCA1 and BRCA2 were reported as high penetrant breast cancer predisposing genes. However, mutations in these genes are found in only a fraction of high risk families. BARD1 is a candidate breast cancer gene, but only a limited number of missense mutations with rather unclear pathogenic consequences have been reported.We screened 196 high risk breast cancer families for the occurrence of BARD1 variants. All genetic variants were analyzed using clinical information as well as IN SILICO predictive tools, including protein modeling. We found three candidate pathogenic mutations in seven families including a first case of a protein truncating mutation (p.Glu652fs) removing the entire second BRCT domain of BARD1. In conclusion, we provide evidence for an increased breast cancer risk associated to specific BARD1 germline mutations. However, these BARD1 mutations occur in a minority of hereditary breast cancer families. ©2010 Wiley‐Liss, Inc.     

Identification of a founder BRCA1 mutation in the Moroccan population

Breast cancer (BC) is the most frequent cancer among women in Morocco. However, the role of the most prevalent BC‐predisposing genes, BRCA1 and BRCA2, has been largely unexplored. To help define the role of BRCA1 in BC in Morocco, we characterized the first potential BRCA1 founder mutation in this population. Genetic testing of BRCA1 and BRCA2 in BC high‐risk families identified mutation BRCA1 c.5309G>T, p.(Gly1770Val) or G1770V in five independent families from Morocco, suggesting a founder effect. To confirm this hypothesis, haplotype construction was performed using seven intragenic and flanking BRCA1 microsatellite markers. Clinical data were also compiled. Clinical data from carriers of mutation G1770V correspond to data from carriers of BRCA1 pathogenic mutations. Microsatellite analysis showed a common haplotype for the five families in a region comprising 1.54 Mb, confirming G1770V as the first specific founder BRCA1 mutation in the Moroccan population. Our findings contribute to a better understanding of BC genetics in the Moroccan population. Nevertheless, comprehensive studies of mutation G1770V in large series of BC patients from Morocco are needed to assess the real prevalence of this mutation and to improve genetic testing and risk assessment in this population.     

Prevalence of BRCA1/2 large genomic rearrangements in Chinese women with sporadic triple‐negative or familial breast cancer

The prevalence of BRCA1/2 large genomic rearrangements (LGRs) and their underlying mechanisms have not been fully evaluated in Chinese women with breast cancer. In this study, we determined the prevalence of BRCA1/2 LGRs in 834 patients with familial breast cancer (FBC) and 660 patients with sporadic triple‐negative breast cancer (TNBC) who were negative for BRCA1/2 small‐range mutations using the multiplex ligation‐dependent probe amplification method. We found that 20 index patients (2.4%) in the FBC group carried a BRCA1 or BRCA2 LGR, and the frequencies of BRCA1 and BRCA2 LGRs were 1.6% and 0.8%, respectively. Seven index patients (1.1%) carried a BRCA1 LGR in 660 sporadic TNBC patients, whereas no BRCA2 LGRs were found in these patients. Among the BRCA1/2 LGRs, 48.1% (13/27) were novel, and the breakpoints of the majority of the LGRs were identified. ΨBRCA1‐mediated homologous recombination (HR) and Alu‐mediated HR/non‐homologous end‐joining (NHEJ) accounted for 40% and 30% of the BRCA1 LGRs, respectively. Alu‐mediated HR accounted for 71.4% of the BRCA2 LGRs, and the remaining one‐third was generated through Long interspersed nuclear elements (LINE)‐mediated NHEJ. Our findings suggest that both FBC patients and sporadic TNBC patients should be tested for BRCA1/2 LGRs.     

Functional Analysis of BARD1 Missense Variants in Homology‐Directed Repair of DNA Double Strand Breaks

Genes associated with hereditary breast and ovarian cancer (HBOC) are often sequenced in search of mutations that are predictive of susceptibility to these cancer types, but the sequence results are frequently ambiguous because of the detection of missense substitutions for which the clinical impact is unknown. The BARD1 protein is the heterodimeric partner of BRCA1 and is included on clinical gene panels for testing for susceptibility to HBOC. Like BRCA1, it is required for homology‐directed DNA repair (HDR). We measured the HDR function of 29 BARD1 missense variants, 27 culled from clinical test results and two synthetic variants. Twenty‐three of the assayed variants were functional for HDR; of these, four are known neutral variants. Three variants showed intermediate function, and three others were defective in HDR. When mapped to BARD1 domains, residues crucial for HDR were located in the N‐ and C‐ termini of BARD1. In the BARD1 RING domain, critical residues mapped to the zinc‐coordinating amino acids and to the BRCA1‐BARD1 binding interface, highlighting the importance of interaction between BRCA1 and BARD1 for HDR activity. Based on these results, we propose that the HDR assay is a useful complement to genetic analyses to classify BARD1 variants of unknown clinical significance.     

Germline RAD51C mutations in ovarian cancer susceptibility

Several genes might explain BRCA1/2 negative breast and ovarian family cases. Deleterious mutations in few genes involved in the Fanconi complex are responsible for Fanconi anemia at the homozygous state and breast cancer (BC) susceptibility at the heterozygous state (BRCA2, PALB2, BRIP1). RAD51C plays an important role in the double‐strand break repair pathway and a biallelic missense mutation in the RAD51C gene was found in a Fanconi anemia‐like disorder. Subsequently, six monoallelic pathogenic mutations were identified after screening 480 BRCA1/2 negative breast and ovarian cancer (BC/OC) pedigrees. Several reports were unsuccessful to replicate these results. To investigate whether germline mutations in RAD51C are associated with an increased risk of developing BC/OC, we screened, by Sanger sequencing of the coding sequence, 117 index cases of breast and ovarian families from French or European origin, and negative for BRCA1/2 mutations. In our study, we found 3 pathogenic mutations among 117 families screened which corresponds to a 2.6% frequency. Our results confirm that RAD51C is a susceptibility gene for ovarian and BC and that this gene should be screened for mutations in families with multiple BC/OC.     

Mutational spectrum in a worldwide study of 29,700 families with BRCA1 or BRCA2 mutations

The prevalence and spectrum of germline mutations in BRCA1 and BRCA2 have been reported in single populations, with the majority of reports focused on White in Europe and North America. The Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) has assembled data on 18,435 families with BRCA1 mutations and 11,351 families with BRCA2 mutations ascertained from 69 centers in 49 countries on six continents. This study comprehensively describes the characteristics of the 1,650 unique BRCA1 and 1,731 unique BRCA2 deleterious (disease‐associated) mutations identified in the CIMBA database. We observed substantial variation in mutation type and frequency by geographical region and race/ethnicity. In addition to known founder mutations, mutations of relatively high frequency were identified in specific racial/ethnic or geographic groups that may reflect founder mutations and which could be used in targeted (panel) first pass genotyping for specific populations. Knowledge of the population‐specific mutational spectrum in BRCA1 and BRCA2 could inform efficient strategies for genetic testing and may justify a more broad‐based oncogenetic testing in some populations.     

High proportion of novel mutations of<Emphasis Type="Italic"> BRCA1</Emphasis> and<Emphasis Type="Italic"> BRCA2</Emphasis> in breast/ovarian cancer patients from Castilla-León (central Spain)

A total of 264 unrelated breast/ovarian cancer patients and 45 healthy individuals with familial antecedents referred for genetic testing were scanned for germ-line mutations in BRCA1 and BRCA2 by conformation-sensitive gel electrophoresis (CSGE) and heteroduplex analysis by capillary array electrophoresis (HA-CAE). We detected 101 distinct mutations (41 in BRCA1 and 60 in BRCA2); ten of them have not been previously reported. These mutations were c.2411_2429dup19, c.2802_2805delCAAA and c.5294A>G (p.E1725E) of BRCA1; and c.667C>T (p.Q147X), c.2683C>T (p.Q819X), c.5344_5347delAATA, c.5578_5579delAA;insT, c.8260_8261insGA, c.744+14C>T and c.8099A>G (p.Y2624C) of BRCA2. Twenty-four different mutations, including seven of the new mutations (five frameshift and two nonsense), were classified as pathogenic. These 24 alterations were found in 39 families (12.6% of all families). A remarkable proportion of deleterious mutations were found in BRCA2: 25 families carried a mutation in BRCA2 (BRCA2+; 64.1%) compared with 14 families BRCA1+ (35.9%). The highest incidences of deleterious mutations were found in families with three or more cases of site-specific breast cancer (BC) (27.4%) and families with BC and ovarian cancer (22.2%). Finally, four recurrent mutations, 3036_3039delACAA, c.5374_5377delTATG of BRCA2, as well as c.5272-1G>A and c.5242C>A (p.A1708E) of BRCA1, accounted for 44% of all of the deleterious mutations.     

BRCA1 and BRCA2 mutation analysis in breast-ovarian cancer families from northeastern Poland

Sixty high-risk breast and/or ovarian cancer families from North-Eastern Poland were screened for germline mutations in BRCA1 (MIM# 113705) and BRCA2 (MIM# 600185), using a combination of protein truncation test, denaturing high-performance liquid chromatography and direct sequencing. Sixteen (27%) of the families were found to carry nine different BRCA mutations, including 14 families with BRCA1 mutation and two families with BRCA2 mutation. The results suggest the presence of two strong BRCA1 founder mutations in the Polish population - 5382insC (6 families) and 300T>G (Cys61Gly; 3 families). The remaining seven mutations were found in single families and included three previously reported BRCA1 mutations (185delAG, 2682C>T [Gln855Ter] and 3819del5), a novel BRCA1 mutation (IVS14+1G>A), as well as two BRCA2 mutations (4088delA and 7985G>A [Trp2586Ter]) not previously observed in Polish families. We confirm the strong influence of two Central-Eastern European BRCA1 founder mutations in familial breast and/or ovarian cancer in Poland. We also conclude that the Polish population has a more dispersed BRCA mutation spectrum than had been earlier thought. This warrants further careful BRCA mutation screening in order to optimise genetic counselling and disease prevention in affected families.     

BRCA1/2 testing: uptake, phenocopies, and strategies to improve detection rates in initially negative families

Fischer C, Engel C, Sutter C, Zachariae S, Schmutzler R, Meindl A, Heidemann S, Grimm T, Goecke TO, Debatin I, Horn D, Wieacker P, Gadzicki D, Becker K, Schäfer D, Stock F, Voigtländer T, on behalf of the German Consortium for Hereditary Breast and Ovarian Cancer. BRCA1/2 testing: uptake, phenocopies, and strategies to improve detection rates in initially negative families. In families with clustering of breast and ovarian cancer, molecular testing of the major susceptibility genes BRCA1/2 helps to identify patients with disease mutations and healthy persons at high risk who can participate in targeted intervention programs. We investigated 5559 families from the German Consortium for Hereditary Breast and Ovarian Cancer included between 1997 and 2008 and treated under clinical routine conditions. In each family an index patient/person had been screened for deleterious mutations in BRCA1/2. Healthy relatives agreed to predictive testing in 888 of 1520 BRCA1/2 mutation‐positive families (58%). Of 2646 eligible unaffected first‐degree relatives 1143 decided to be tested (43%). In 325 families with BRCA1/2‐positive index patients one related BC/OC patient was tested and 39 (12.0%; 95% confidence interval: 8.7–16.0%) discrepant cases found. A second related individual was screened in 163 of 3388 (4.9%) families with BRCA1/2‐negative index patient and in eight families a BRCA1/2 mutation was found. In BRCA1/2 mutation‐positive families, BC/OC patients lacking the familial mutation have to be expected at a rather high rate. In families with BRCA1/2‐negative index patient we recommend a second screening if another patient with a high probability of carrying a BRCA1/2 mutation is available.     

Comprehensive profiling of BRCA1 and BRCA2 variants in breast and ovarian cancer in Chinese patients

The identification and interpretation of germline BRCA1/2 variants become increasingly important in breast and ovarian cancer (OC) treatment. However, there is no comprehensive analysis of the germline BRCA1/2 variants in a Chinese population. Here we performed a systematic review and meta‐analysis on such variants from 94 publications. A total of 2,128 BRCA1/2 variant records were extracted, including 601 from BRCA1 and 632 from BRCA2. In addition, 414, 734, 449, and 307 variants were also recorded in the BIC, ClinVar, ENIGMA, and UMD databases, respectively, and 579 variants were newly reported. Subsequent analysis showed that the overall germline BRCA1/2 pathogenic variant frequency was 5.7% and 21.8% in Chinese breast and OC, respectively. Populations with high‐risk factors exhibited a higher pathogenic variant percentage. Furthermore, the variant profile in Chinese is distinct from that in other ethnic groups with no distinct founder pathogenic variants. We also tested our in‐house American College of Medical Genetics‐guided pathogenicity interpretation procedure for Chinese BRCA1/2 variants. Our results achieved a consistency of 91.2–97.6% (5‐grade classification) or 98.4–100% (2‐grade classification) with public databases. In conclusion, this study represents the first comprehensive meta‐analysis of Chinese BRCA1/2 variants and validates our in‐house pathogenicity interpretation procedure, thereby providing guidance for further PARP inhibitor development and companion diagnostics in the Chinese population.     

High proportion of missense mutations of the BRCA1 and BRCA2 genes in Japanese breast cancer families

Mutations in either of two recently identified genes, BRCA1 and BRCA2, are thought to be responsible for approximately two-thirds of all cases of autosomal-dominantly inherited breast cancer. To examine the nature and frequency of BRCA1 and BRCA2 mutations in Japanese families exhibiting a high incidence of breast cancer, we screened 78 unrelated families in this category for mutations of these two genes. Examining the entire coding sequences as well as exon–intron boundaries of both genes by polymerase chain reaction (PCR) single-strand conformation polymorphism (SSCP) and multiplex-SSCP analysis, we identified possible disease-causing alterations in BRCA1 among affected members of 15 families and in BRCA2 in another 14 families. In 15 of those 29 families, the affected individuals carried missense mutations, although most germline mutations reported worldwide have been deletions or nonsense mutations. Our results, indicating that missense mutations of BRCA1 and BRCA2 tend to predominate over frameshifts or nonsense mutations in Japanese breast cancer families, will contribute signifi-cantly to an understanding of mammary tumorigenesis in Japan, and will be of vital importance for future genetic testing. Received: September 4, 1997 / Accepted: October 28, 1997     

Angiogenetic axis angiopoietins/Tie2 and VEGF in familial breast cancer

Angiogenesis leads to the formation of blood vessels from pre-existing ones, allowing tumor growth. Vascular endothelial growth factor (VEGF) and Angiopoietins (Ang-1, Ang-2) have a pivotal role in tumor angiogenesis but few data regarding their role in hereditary breast cancer are available. The aim of the present study was to analyze Ang-1, Ang-2, tyrosine-protein kinase receptor Tie2 and VEGF expression and their correlation in a cohort of familial and sporadic breast cancers in order to verify whether the presence of germline mutations in BRCA may have a role in tumor microenvironment regulation. Tumor samples from a cohort of 41 patients with a first diagnosis and a family history of breast cancer and 19 patients with sporadic breast cancers were enrolled. The expression of Tie2, Ang-1, Ang-2 and VEGF were analyzed by quantitative real-time PCR. Patients harboring BRCA mutations had higher levels of Ang-1 (P=0.05), Ang-2 (P=0.02) and VEGF (P=0.04) mRNA compared with those without BRCA mutations (BRCAX). The same was observed in triple-negative breast cancer (TNBC). Moreover, a positive correlation between Ang-2 and VEGF was found in both the familial breast cancer group (BRCA carriers: r=0.83; P<0.0001 and BRCAX: r=0.58; P=0.008) and in TNBC (r=0.62; P=0.007). The higher levels of Ang-1, Ang-2 and VEGF mRNA found in BRCA carriers and TNBCs suggest that they could be attractive angiogenic therapeutic targets in these breast cancers.     

BARD1 homozygous deletion,a possible alternative to BRCA1 mutation in basal breast cancer

Hereditary breast cancers (BCs) are incompletely explained by BRCA genes abnormalities, as ～70% of them are not associated with known genetic alterations. Array‐based comparative genomic hybridization (aCGH) of tumors provides an opportunity for identifying new BC susceptibility genes. By analyzing our database of high‐resolution aCGH profiles of 330 BCs, we identified a case with homozygous deletion of the entire BARD1 gene. The BARD1‐deleted case displayed a familial history of BC and other clinico‐pathological features of BRCAness, and a 17% probability of BRCA1/2 mutation. Analysis of constitutional DNA showed a BARD1 germline heterozygous deletion without BRCA1/2 mutation. Gene expression analysis using DNA microarrays classified the tumor as basal‐like, with very low BARD1 and ID4 expression, but high expression of BRCA1, RAD51, PARP1, CHEK1, and FANCA. The tumor displayed a BRCA1‐mutated expression profile. This is the first report of a non‐BRCA1/2‐mutated BC with somatic homozygous and germ‐line heterozygous deletion of the entire BARD1 gene. This observation suggests that BARD1 might be a BC susceptibility gene that follows the Knudson rule. Identification of BARD1 deletion could have clinical applications including screening for hereditary forms. © 2010 Wiley‐Liss, Inc.     

The role of targeted BRCA1/BRCA2 mutation analysis in hereditary breast/ovarian cancer families of Portuguese ancestry

We report the analysis of altogether 1050 suspected hereditary breast/ovarian cancer (HBOC) families, 524 fully screened for BRCA1/BRCA2 mutations and 526 tested only for the most common mutations. Of the 119 families with pathogenic mutations, 40 (33.6%) had the BRCA2 c.156_157insAlu rearrangement and 15 (12.6%) the BRCA1 c.3331_3334del mutation, the former being specific of Portuguese ancestry and the latter showing a founder effect in Portugal. Interestingly, the two most common mutations were found in a significant proportion of the HBOC families with an a priori BRCAPRO mutation probability <10%. We recommend that all suspected HBOC families from Portugal or with Portuguese ancestry, even those fulfilling moderately stringent clinical‐criteria for genetic testing, should be specifically analyzed for the two most common BRCA1/BRCA2 founder mutations, and we here present a simple method for this first tier test. Screening of the entire coding regions of BRCA1 and BRCA2 should subsequently be offered to those families with a mutation probability ≥10% if none of those founder mutations are found.     

Prevalence,spectrum, and founder effect of BRCA1 and BRCA2 mutations in epithelial ovarian cancer from the Middle East

Germline mutations in breast cancer susceptibility gene 1 and 2 have previously been estimated to contribute to 13–18% of all epithelial ovarian cancer (EOC). To characterize the prevalence and effect of BRCA1 and BRCA2 mutations in Middle Eastern EOC patients, BRCA mutation screening was performed in 407 unselected ovarian cancer patients using targeted capture and/or Sanger sequencing. A total of 19 different pathogenic variants (PVs) were identified in 50 (12.3%) women. Nine PVs were recurrent accounting for 80% of cases with PVs (40/50) in the entire cohort. Founder mutation analysis revealed only two mutations (c.4136_4137delCT and c.1140dupG) sharing the same haplotypes thus representing founder mutations in the Middle Eastern population. Identification of the mutation spectrum, prevalence, and founder effect in Middle Eastern population facilitates genetic counseling, risk assessment, and development of a cost‐effective screening strategy.     

BRCA1 Germ‐Line Mutations and Tumor Characteristics in Eastern Chinese Women with Familial Breast Cancer

Although several studies detected the BRCA1 germ‐line mutations in Chinese women with familial breast cancer, most of them did not employ conventional full gene sequencing, especially in eastern China. In addition, the clinicopathological features of BRCA1‐associated breast cancer in Chinese women were not well investigated. In this study, we screened the complete coding regions and exon‐intron boundaries of BRCA1 by polymerase chain reaction (PCR)‐sequencing assay. Immunohistochemistry analyses were performed on tumor samples to detect the expression of estrogen receptor (ER), progesterone receptor (PR), P53, and human epidermal growth factor receptor‐2 (HER‐2). Breast cancer patients having one or more affected relatives referred from the Zhejiang Cancer Hospital, eastern China during 2008–2011 were selected for the study. A total of 62 familial breast cancer patients received the BRCA1 germ‐line mutation screening. Five deleterious mutations were detected in this cohort. The mutation rate was 11.3% (7/62). We found two novel mutations (3414delC and 5,280 C > T) and two recurrent mutations (5,273 G > A and 5589del8). BRCA1 mutation tumors tended to be negative for ER, PR, and HER‐2, and exhibited high histological grade compared with tumors without BRCA1 mutations. Our study suggests that recurrent mutations may exist in eastern Chinese women with familial breast cancer and PCR‐sequencing assay is a useful tool to screen these mutations. It also suggests that BRCA1‐associated breast cancers in Chinese women exhibit an aggressive phenotype. Anat Rec, 2013. © 2012 Wiley Periodicals, Inc.     

Novel BRCA1 and BRCA2 Tumor Test as Basis for Treatment Decisions and Referral for Genetic Counselling of Patients with Ovarian Carcinomas

With the recent introduction of Poly(ADP‐ribose) polymerase inhibitors, a promising novel therapy has become available for ovarian carcinoma (OC) patients with inactivating BRCA1 or BRCA2 mutations in their tumor. To select patients who may benefit from these treatments, assessment of the mutation status of BRCA1 and BRCA2 in the tumor is required. For reliable evaluation of germline and somatic mutations in these genes in DNA derived from formalin‐fixed, paraffin‐embedded (FFPE) tissue, we have developed a single‐molecule molecular inversion probe (smMIP)‐based targeted next‐generation sequencing (NGS) approach. Our smMIP‐based NGS approach provides analysis of both strands of the open reading frame of BRCA1 and BRCA2, enabling the discrimination between real variants and formalin‐induced artefacts. The single molecule tag enables compilation of unique reads leading to a high analytical sensitivity and enabling assessment of the reliability of mutation‐negative results. Multiplex ligation‐dependent probe amplification (MLPA) and Methylation‐specific multiplex ligation‐dependent probe amplification (MS‐MLPA) were used to detect exon deletions of BRCA1 and methylation of the BRCA1 promoter, respectively. Here, we show that this combined approach allows the rapid and reliable detection of both germline and somatic aberrations affecting BRCA1 and BRCA2 in DNA derived from FFPE OCs, enabling improved hereditary cancer risk assessment and clinical treatment of ovarian cancer patients.     

BRCA1 and BRCA2 Germline Mutations Screening in Algerian Breast/Ovarian Cancer Families

Background: Breast cancer is the leading cause of cancer death in women in Algeria. The contribution of BRCA1 and BRCA2 mutations to hereditary breast/ovarian cancer in Algerian population is largely unknown. Here, we describe analysis of BRCA1 and BRCA2 genes in 86 individuals from 70 families from an Algerian cohort with a personal and family history suggestive of genetic predisposition to breast cancer. Methods: The approach used is based on BRCA1 and BRCA2 mutations screening by High-Resolution Melting (HRM) curve analysis followed by direct sequencing. All samples for which no pathogenic mutation was found were analyzed by MLPA for large deletions or duplications. Results: Three distinct pathogenic mutations c.83_84delTG, c.181T>G, c.798_799delTT and two large rearrangements involving deletion of exon 2 and exon 8 respectively, were detected in BRCA1 gene. Moreover 17 unclassified variants and polymorphisms were detected in BRCA1 gene (6 described for the first time). Two pathogenic mutations, c.1310_1313delAAGA and c.5722_5723delCT and 40 unclassified variants and polymorphisms (14 never described before) were identified in BRCA2 gene. Conclusions: For the first time, we used HRM and MLPA to identify BRCA1 and BRCA2 mutations in Algerian patients with a personal and family history suggestive of genetic predisposition to breast cancer. The implications of these new findings in regard to genetic testing and counseling are substantial for the Algerian population.     

BRCA1 and BRCA2 mutations in Russian familial breast cancer

We have screened index cases from 25 Russian breast/ovarian cancer families for germ‐line mutations in all coding exons of the BRCA1 and BRCA2 genes, using multiplex heteroduplex analysis. In addition we tested 22 patients with breast cancer diagnosed before age 40 without family history and 6 patients with bilateral breast cancer. The frequency of families with germline mutations in BRCA was 16% (4/25). One BRCA1 mutation, 5382insC, was found in three families. The results of present study, and those of a separate study of 19 breast‐ovarian cancer families, suggest that BRCA1 5382insC is a founder mutation in the Russian population. Three BRCA2 mutations were found in patients with breast cancer without family history: two in young patients and one in patients with bilateral breast cancer. Four novel BRCA2 mutations were identified: three frameshift (695insT, 1528del4, 9318del4) and one nonsense (S1099X). © 2002 Wiley‐Liss, Inc.