Detecting BRCA2 Protein Truncation in Tissue Biopsies to Identify Breast Cancers That Arise in BRCA2 Gene Mutation Carriers

Purpose Mutations in the BRCA2 gene are dominantly inherited but cause cancers when the wild-type allele has loss of heterozygosity (LOH) within the cancer. Because most disease-associated BRCA2 mutations are protein-truncating mutations, a test for truncated BRCA2 proteins should identify most BRCA2 hereditary cancers. Methods We have developed a tissue truncation test to identify truncated BRCA2 proteins in breast cancer tissue biopsies in vivo that does not use amplification or genetic manipulations. N-terminal and C-terminal antibodies are used to visualize protein truncation by demonstrating that the beginning of the protein is present but the end (ie, terminus) is absent. Results A quantitative C-terminal immunostaining score or a C-terminal to N-terminal truncation ratio correctly classified 20 of 21 breast cancers arising in BRCA2 mutation carriers and 57 of 58 cancers arising outside the context of a multiple-case breast cancer family. This represents a sensitivity of 95% and a specificity of 98%. Because of the presence of C-terminal BRCA2 protein and atypical clinical features of the misclassified cancer in a BRCA2 mutation carrier, we performed polymerase chain reaction and sequence analyses on this cancer. The results showed continued presence of the BRCA2 wild-type allele in the cancer, which indicated that intact BRCA2 protein was present in this cancer. Conclusion This immunohistochemistry-based test (which takes only 4 hours) appears to identify BRCA2 hereditary cancer with high accuracy. The test also appears to diagnose the biochemical loss of BRCA2 protein in cancers (ie, BRCA2-mutant genotype), which will usually but not always agree with the presence of a germline BRCA2 mutation found by susceptibility testing by DNA sequencing of blood samples.

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Common variants of the BRCA1 wild-type allele modify the risk of breast cancer in BRCA1 mutation carriers

Human Molecular Genetics ◽

10.1093/hmg/ddr388 ◽

2011 ◽

Vol 20 (23) ◽

pp. 4732-4747 ◽

Cited By ~ 21

Author(s):

David G. Cox ◽

Jacques Simard ◽

Daniel Sinnett ◽

Yosr Hamdi ◽

Penny Soucy ◽

...

Keyword(s):

Breast Cancer ◽

Brca1 Mutation ◽

Wild Type Allele ◽

Common Variants ◽

Wild Type ◽

Type Allele ◽

Mutation Carriers

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Loss of heterozygosity at the BRCA2 locus is a common finding in prostate cancer in men with a germline BRCA2 mutation

Journal of Clinical Oncology ◽

10.1200/jco.2007.25.18_suppl.10539 ◽

2007 ◽

Vol 25 (18_suppl) ◽

pp. 10539-10539

Author(s):

S. Dawson ◽

A. Willems ◽

H. Thorne ◽

H. Samaratunga ◽

Y. C. Antill

Keyword(s):

Prostate Cancer ◽

Loss Of Heterozygosity ◽

Brca2 Mutation ◽

Common Finding ◽

Wild Type Allele ◽

Wild Type ◽

Prostate Tumorigenesis ◽

Type Allele ◽

Brca1 Carriers ◽

Male Carriers

10539 Background: The prevalence of prostate cancer (PC) is higher in men with a germline mutation in BRCA2 and to a lesser extent BRCA1. It is unclear as to whether a causal relationship exists between these mutations and PC tumorigenesis. The primary aim of this pilot study was to examine for loss of heterozygosity (LOH) in PC samples from men with a known BRCA1/2 mutation. Secondary aims included assessment of the clinical and pathological features of PC in these individuals. Methods: Subjects were male carriers of a germline BRCA1/2 mutation enrolled in kConFab with a diagnosis of PC. LOH analysis was performed using multiplex ligation-dependent probe amplification and confirmed using PCR and sequencing. Clinical data was obtained on all individuals together with histopathology review. Results: In total, 134 pedigrees from BRCA1/2 mutation positive families known to include = 1men with PC were reviewed; 192 men were identified as having PC, however, only 26 were found to carry a pathogenic family specific mutation. Of these, 14 were ineligible as prostate tissue was unavailable. LOH was therefore assessed in 12 subjects (3 BRCA1 and 9 BRCA2). LOH at the BRCA2 locus was seen in 8/9 (89%) subjects with a BRCA2 mutation whilst the ninth showed no LOH. None of the samples from BRCA1 carriers were found to have LOH at the BRCA1 locus. For samples showing LOH, sequencing confirmed loss of the wild-type allele. No unique clinical or histopathological subtype was identified. Conclusions: LOH appears to occur very frequently at the BRCA2 locus in PC arising in men known to carry a germline BRCA2 mutation with LOH heavily biased towards loss of the wild-type allele. Whilst the cohort studied is small, these two results strongly indicate that BRCA2 is a tumour suppressor of PC and is the first gene shown to have this property. In contrast, failure to identify LOH in the BRCA1 samples suggests that BRCA1 is unlikely to be integral in the development of PC. These results should be confirmed in a larger cohort and further research into the mechanisms of BRCA2 induced prostate tumorigenesis is warranted. No significant financial relationships to disclose.

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Correlation of breast cancer risk in European BRCA2 mutation carriers with birth cohort.

Journal of Clinical Oncology ◽

10.1200/jco.2012.30.15_suppl.1537 ◽

2012 ◽

Vol 30 (15_suppl) ◽

pp. 1537-1537

Author(s):

Muy-Kheng Maria Tea ◽

Regina Kroiss ◽

Daniela Muhr ◽

Christine Fuerhauser-Rappaport ◽

Teresa M. U. Wagner ◽

...

Keyword(s):

Breast Cancer ◽

Cancer Risk ◽

Birth Cohort ◽

Brca2 Mutation ◽

Molecular Genetic ◽

Brca2 Gene ◽

Cancer Gene ◽

Mutation Carriers ◽

Study Population ◽

Breast Cancer Gene

1537 Background: Mutations in the Breast Cancer Gene 1 (BRCA1) and Breast Cancer Gene 2 (BRCA2) lead to an elevated risk of developing breast (BC) and ovarian cancer (OC). However, risk estimates vary, depending on the study population. Furthermore, there are indications that birth cohort can influence the cancer risk. We investigated the risks for BC and OC associated with BRCA2 mutations in a cohort of female mutation carriers of a genetically heterogeneous central European population who were identified by molecular genetic testing in our institute. Methods: This study included 171 Caucasian women from Austria who underwent genetic counseling and where molecular genetic analysis identified a mutation in the BRCA2 gene at the Medical University of Vienna, Division of Senology, in Austria. A total of 57 healthy and 114 affected BRCA2-carriers were detected. The risk was estimated using the product limit method. The log rank test was used to compare different strata. Results: The risk of developing cancer to age 70 was found to be 85% for BC (95% CI 77–93%) and 31% for OC (95% CI 16–46%) in our BRCA2 study population. Female BRCA2-carriers born in 1958 or later were at a significantly higher risk of developing BC (p<0.001; 88% vs. 46% to age 40) but not of OC (p is not significant; 0% vs. 2% to age 40) compared to mutation carriers born earlier. Conclusions: We conclude that female BRCA2 mutation carriers should also be counseled about their cohort-dependent cancer risk, especially for breast cancer. Further research about variables that may affect cancer risk like lifestyle-related factors should be considered.

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Update on chemoprevention in BRCA1 and BRCA2 mutation carriers

Breast Cancer Online ◽

10.1017/s1470903105002890 ◽

2005 ◽

Vol 8 (9) ◽

Author(s):

M. Stumacher ◽

S. M. Domchek

Keyword(s):

Breast Cancer ◽

Prophylactic Mastectomy ◽

Brca Mutation ◽

Brca2 Mutation ◽

Breast Cancers ◽

Brca1 And Brca2 ◽

Prophylactic Oophorectomy ◽

Estrogen Exposure ◽

Mutation Carriers ◽

Increased Risk

Chemoprevention with tamoxifen and oophorectomy are thought to be effective in decreasing the incidence of breast cancer in women at increased risk for the disease. There is mounting data supporting the idea that hormonal interventions that reduce estrogen exposure to breast epithelium, such as prophylactic oophorectomy and tamoxifen, are effective in breast cancer prevention in both BRCA1 and BRCA2 mutations carriers. Several recent studies directly address the protective effect of tamoxifen and oophorectomy in BRCA mutation carriers and suggest that these endocrine manipulations decrease the risk of primary and secondary breast cancers. Ongoing studies aim to better define the effect of tamoxifen in these very high-risk women and determining whether factors, such as earlier age of use or prior prophylactic oophorectomy, impact tamoxifen's effect. Based on existing data, we recommend that women with deleterious mutations in BRCA1 or BRCA2 be informed of the beneficial effect of oophorectomy on breast cancer risk and that women who choose breast cancer screening instead of prophylactic mastectomy be offered tamoxifen as a prevention option.

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Characteristics of breast cancer in BRCA1/BRCA2 mutation carriers and non-carriersfrom a genetic counseling unit in Croatia

Libri Oncologici Croatian Journal of Oncology ◽

10.20471/lo.2020.48.02-03.10 ◽

2020 ◽

Vol 48 (2-3) ◽

pp. 54-60

Author(s):

Snježana Ramić ◽

◽

Gabriela Alfier ◽

Iva Kirac ◽

Ivan Milas ◽

...

Keyword(s):

Breast Cancer ◽

Family History ◽

Brca2 Mutation ◽

Significant Risk ◽

Brca2 Gene ◽

Cancer Risk Assessment ◽

Luminal B ◽

Mutation Carriers ◽

Breast Cancer Risk Assessment ◽

Brca1 Brca2

Breast cancer (BC) represents 25% of all malignancies in Croatian women, and in 18.8% of cases, it is diagnosed before the age of 50. Croatia launched BRCA testing of people at increased family risk. Hereditary BC is mainly caused by a pathogenic mutation in the BRCA1 or BRCA2 gene and is a significant risk factor for developing breast and ovarian cancer. The present study included 127 women diagnosed with BC, with a strong family history of BC and the known status of the germline mutations in the BRCA1/BRCA2 genes. The majority of women were BRCA1/2 mutation non-carriers, while 15.7% were BRCA1/2 mutation carriers, and 4% had a variant of unknown significance (VUS). BRCA1/2 mutation carriers were younger than non-carriers (median 38.5 years vs. 44 years) (P=.01) and had tumors of higher histological grade (P<.001). The intrinsic subtype of BC differs significantly depending on the type of mutation (P<.001). Triple-negative BC prevailed (87.5%) in BRCA1 mutation carriers, and 12.5% had a luminal B/HER2-negative BC. Four patients were BRCA2 mutation carriers, and two of them had luminal B/HER2-positive BC. Most BRCA1/2 non-carriers (69.2%) and all VUS-carriers have luminal B/HER2-negative BC. Our results show that BRCA1/2 mutation testing is essential for women with a family history burden. It is a piece of valuable information in breast cancer risk assessment and contributes to early diagnosis.

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Breast cancer detection among Irish BRCA1 and BRCA2 mutation carriers.

Journal of Clinical Oncology ◽

10.1200/jco.2012.30.15_suppl.e12038 ◽

2012 ◽

Vol 30 (15_suppl) ◽

pp. e12038-e12038 ◽

Cited By ~ 1

Author(s):

Elaine Walsh ◽

Michael P. Farrell ◽

Fergal Gallagher ◽

Roisin Clarke ◽

Carmel Nolan ◽

...

Keyword(s):

Breast Cancer ◽

Brca Mutation ◽

Brca2 Mutation ◽

Interval Cancer ◽

Breast Cancers ◽

Interval Cancers ◽

Brca1 And Brca2 ◽

Clinical Breast Exam ◽

Mutation Carriers ◽

Clinical Breast

e12038 Background: High-risk breast cancer screening for BRCA1/2 mutations carriers with clinical breast exam, mammography and MRI have sensitivities approaching 100%. Even with intensive screening BRCA mutation carriers can present with self-detected interval cancers. We investigate screening practices and presentation among a cohort of Irish BRCA1/2 mutation carriers. Methods: Females with breast cancer belonging to kindreds now known to harbour BRCA1/2 mutations were retrospectively identified. Records were reviewed for BRCA mutation, demographics, breast cancer diagnosis, stage, histology and screening. We assessed screening modalities and whether breast cancers were diagnosed at screening or as interval cancers. Results: 53 cases of breast cancer were diagnosed from 1968-2010 among 53 Irish hereditary breast ovarian cancer kindreds. BRCA mutation status was unknown at time of diagnosis but subsequently confirmed. Detection method was identified in 50% of patients: 84% by clinical breast exam (CBE), 4% mammography, 4% MRI and 8% by a combination of CBE and mammography. Fifteen women (28%) developed second breast cancer; 9(60%) were undergoing screening, 2 were not and 27% were unknown. 22% were detected by CBE alone; 34% mammography; 22% a combination of mammography and CBE and 22% by MRI. In 41%, histology changed between first and second diagnosis. Two women developed a third breast cancer. In one, her second was an interval cancer despite being in a screening programme. Her third was radiologically detected. Conclusions: In this cohort of Irish BRCA1/2 mutation carriers almost 25% of second breast cancers were not detected by screening. 4% of cases were phenocopies and in 41% histology changed between first and second diagnosis. [Table: see text]

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CHEK2 variants in susceptibility to breast cancer and evidence of retention of the wild type allele in tumours

British Journal of Cancer ◽

10.1038/sj.bjc.6600637 ◽

2002 ◽

Vol 87 (12) ◽

pp. 1445-1448 ◽

Cited By ~ 41

Author(s):

N Sodha ◽

S Bullock ◽

R Taylor ◽

G Mitchell ◽

B Guertl-Lackner ◽

...

Keyword(s):

Breast Cancer ◽

Wild Type Allele ◽

Wild Type ◽

Type Allele

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BRCA1-Associated Breast Cancers Present Differently From BRCA2-Associated and Familial Cases: Long-Term Follow-Up of the Dutch MRISC Screening Study

Journal of Clinical Oncology ◽

10.1200/jco.2009.27.2294 ◽

2010 ◽

Vol 28 (36) ◽

pp. 5265-5273 ◽

Cited By ~ 126

Author(s):

Adriana J. Rijnsburger ◽

Inge-Marie Obdeijn ◽

Reinoutje Kaas ◽

Madeleine M.A. Tilanus-Linthorst ◽

Carla Boetes ◽

...

Keyword(s):

Breast Cancer ◽

Brca2 Mutation ◽

Risk Groups ◽

Long Term Results ◽

Breast Cancers ◽

Moderate Risk ◽

Mutation Carriers ◽

Screening Study

Purpose The Dutch MRI Screening Study on early detection of hereditary breast cancer started in 1999. We evaluated the long-term results including separate analyses of BRCA1 and BRCA2 mutation carriers and first results on survival. Patients and Methods Women with higher than 15% cumulative lifetime risk (CLTR) of breast cancer were screened with biannual clinical breast examination and annual mammography and magnetic resonance imaging (MRI). Participants were divided into subgroups: carriers of a gene mutation (50% to 85% CLTR) and two familial groups with high (30% to 50% CLTR) or moderate risk (15% to 30% CLTR). Results Our update contains 2,157 eligible women including 599 mutation carriers (median follow-up of 4.9 years from entry) with 97 primary breast cancers detected (median follow-up of 5.0 years from diagnosis). MRI sensitivity was superior to that of mammography for invasive cancer (77.4% v 35.5%; P < .00005), but not for ductal carcinoma in situ. Results in the BRCA1 group were worse compared to the BRCA2, the high-, and the moderate-risk groups, respectively, for mammography sensitivity (25.0% v 61.5%, 45.5%, 46.7%), tumor size at diagnosis ≤ 1 cm (21.4% v 61.5%, 40.9%, 63.6%), proportion of DCIS (6.5% v 18.8%, 14.8%, 31.3%) and interval cancers (32.3% v 6.3%, 3.7%, 6.3%), and age at diagnosis younger than 30 years (9.7% v 0%). Cumulative distant metastasis-free and overall survival at 6 years in all 42 BRCA1/2 mutation carriers with invasive breast cancer were 83.9% (95% CI, 64.1% to 93.3%) and 92.7% (95% CI, 79.0% to 97.6%), respectively, and 100% in the familial groups (n = 43). Conclusion Screening results were somewhat worse in BRCA1 mutation carriers, but 6-year survival was high in all risk groups.

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BRCA2 gene mutations and coagulation-associated biomarkers

Thrombosis and Haemostasis ◽

10.1160/th15-06-0520 ◽

2016 ◽

Vol 115 (02) ◽

pp. 415-423 ◽

Cited By ~ 2

Author(s):

Daniel Acosta ◽

Juana María Santos-Sancho ◽

Javier Modrego ◽

Trinidad Caldés ◽

Miguel de la Hoya ◽

...

Keyword(s):

Breast Cancer ◽

Plasma Levels ◽

Brca2 Mutation ◽

Gene Mutations ◽

Brca2 Gene ◽

Cancer Development ◽

Vitamin D Binding Protein ◽

Mutation Carriers ◽

Alpha1 Antitrypsin ◽

Brca2 Mutations

SummaryThromboembolic events are the second cause of death in cancer patients, although the mechanisms underlying this increased thromboembolic risk remain unclear. The aims of this study were to examine whether BRCA2 gene mutations may modify the circulating levels of thrombocoagulation biomarkers and whether breast cancer development may influence changes in such circulating biomarkers. The study was performed in 25 women with mutations in the BRCA2 gene (n=12 breast cancer, n=13 breast cancer-free) and in 13 BRCA2 nonmutant controls. Results revealed that plasma levels of fibrinogen gamma chain isotypes 2 and 3, haptoglobin isotypes 4 and 5, serotransferrin isotypes 3 and 4 and convertase C3/C5 isotypes 4 and 5 were significantly higher in BRCA2 mutation carriers compared to controls. However, plasma levels of vitamin D binding protein isotype 1 and alpha1-antitrypsin isotypes 2, 3 and 4 were significantly decreased in BRCA2 mutation carriers compared to controls. Plasma expression of PF4 and P-selectin was significantly higher in BRCA2 mutations carriers than in controls. BRCA2 truncated mutations conserving a binding region for RAD51 were associated with increased plasma levels of alpha1-antitrypsin isotypes 3 and 4 with respect to women showing BRCA2 mutations that loss the binding RD51 region to BRCA2. Only plasma levels of vitamin D binding protein isotypes 1 and 3 were significantly reduced and alpha 1-antitrypsin isotype 1 was increased in cancer-free BRCA2 mutation carriers compared to BRCA2 mutation carriers with breast cancer. The presence of BRCA2 mutations is associated with increased plasma levels of thrombo-coagulating-related proteins, which are independent to breast cancer development.

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