A low frequency of non-founder BRCA1 mutations in Ashkenazi Jewish breast-ovarian cancer families

The Risks of Breast and Ovarian Cancer Associated with the Ashkenazi Jewish Founder Allele BRCA2 6174delT

Approximately one percent of the Ashkenazi Jewish population carries the BRCA2 6174delT (c.5946del) pathogenic variant. It is important to have accurate knowledge of the risks of breast and ovarian cancer associated with this specific variant so that women may be counselled accordingly. In this prospective study, we estimated the risks of breast and ovarian cancer associated with the 6174delT variant compared with the risks for other pathogenic variants in the BRCA2 gene. The annual risk for developing breast cancer was significantly lower in 246 women who carried the 6174delT variant compared with 721 non-Jewish women who carried a variant at any other locus in BRCA2 (1.2% per year vs. 2.4% per year, p=0.003). We estimated the cumulative risk of breast cancer from age 30 to 70 to be 39% for carriers of the BRCA2 6174delT variant and 61% for carriers of other BRCA2 variants. The annual risk for ovarian or fallopian tube cancer was 0.51% per year for the 233 women who carried the 6174delT variant compared to 0.22% per year for the 1128 carriers of other BRCA2 variants; the difference was not significant. Lower risks for breast cancer associated with 6174delT may not impact screening and prevention choices, however, the discussion should be based on accurate risk assessment.

Hereditary breast and ovarian cancer (HBOC): review of its molecular characteristics, screening, treatment, and prognosis

Breast cancer is a common cancer affecting a large number of patients. Notably, 5–10% of all breast cancer patients are genetically predisposed to cancers. Although the most common breast cancer susceptibility genes are BRCA1 and BRCA2, which are also associated with the risk of developing ovarian and pancreatic cancer, advances in next-generation sequencing (NGS) analysis technology enabled the discovery of several non-BRCA genes responsible for breast and ovarian cancers. Studies on hereditary breast and ovarian cancer (HBOC) involve not only determining the predisposition to developing cancer, but also considering the current treatment for breast cancer, prevention of next cancer, risk diagnosis, and adoption of protective measures for relatives. We present a comprehensive review of HBOC, which will be a useful resource in the clinical setting. Many hereditary tumors, including HBOC, are syndromes characterized by the development of different types of cancer in succession. Taking advantage of knowing predisposition of susceptibility to cancer, it is important to continue and update cancer management protocols, which includes the adoption of preventive measures, countermeasures, and treatments, to accurately assess and prevent the impact of cancer on the quality of life of the next generation of patients.

BRCA mutations in a cohort of Iraqi patients presenting to a tertiary referral center

BACKGROUND

Unique pathogenic mutations in BRCA1 and 2 genes have been reported in different populations of patients originating from the Middle East region. Limited data are available for the Iraqi population. For many reasons a large number of Iraqi patients present to Lebanon for medical care. This is the first report of BRCA full gene sequencing conducted in a cohort of high-risk patients originating from Iraq.

METHODS

This is a retrospective review of Iraqi patients diagnosed with breast or ovarian cancer referred for BRCA mutation testing at the American University of Beirut from January 2012 to October 2018.

RESULTS

Of the 42 Iraqi women who underwent genetic testing at our institution, 3 BRCA pathogenic variants were found. Two mutations in BRCA1 c.224_227delAAAG and c.5431C > T and one mutation in BRCA2 c.5576_5579delTTAA were identified. Three other patients had sequence changes considered as variants of undetermined significance.

CONCLUSION

In this cohort of high-risk patients, one out of the three pathogenic BRCA variants detected has not previously been reported in the Middle Eastern population. Further studies are required to delineate the spectrum of BRCA mutations in the Iraqi population.

Multi-Gene Panel Testing of 23,179 Individuals for Hereditary Cancer Risk Identifies Pathogenic Variant Carriers Missed by Current Genetic Testing Guidelines

Recent advancements in next-generation sequencing have greatly expanded the use of multi-gene panel testing for hereditary cancer risk. Although genetic testing helps guide clinical diagnosis and management, testing recommendations are based on personal and family history of cancer and ethnicity, and many carriers are being missed. Herein, we report the results from 23,179 individuals who were referred for 30-gene next-generation sequencing panel testing for hereditary cancer risk, independent of current testing guidelines-38.7% of individuals would not have met National Comprehensive Cancer Network criteria for genetic testing. We identified a total of 2811 pathogenic variants in 2698 individuals for an overall pathogenic frequency of 11.6% (9.1%, excluding common low-penetrance alleles). Among individuals of Ashkenazi Jewish descent, three-quarters of pathogenic variants were outside of the three common BRCA1 and BRCA2 founder alleles. Across all ethnic groups, pathogenic variants in BRCA1 and BRCA2 occurred most frequently, but the contribution of pathogenic variants in other genes on the panel varied. Finally, we found that 21.7% of individuals with pathogenic variants in genes with well-established genetic testing recommendations did not meet corresponding National Comprehensive Cancer Network criteria. Taken together, the results indicate that more individuals are at genetic risk for hereditary cancer than are identified by current testing guidelines and/or use of single-gene or single-site testing.

Prevalence of nonfounder BRCA1/2 mutations in Ashkenazi Jewish patients presenting for genetic testing at a hereditary breast and ovarian cancer center

BACKGROUND

Genetic assessment in Ashkenazi Jewish (AJ) patients often is limited to BRCA1/2 founder mutation testing. With access to time-efficient and cost-efficient multigene panel testing, some advocate expanding genetic testing in this population. However, to the best of the authors' knowledge, rates of nonfounder BRCA1/2 mutations and mutations in cancer-associated genes other than BRCA1/2 among AJ are not known. In the current study, the authors sought to assess the prevalence of mutations other than BRCA1/2 founder mutations among AJ patients undergoing genetic assessment.

METHODS

The authors reviewed the medical records for all AJ patients who underwent genetic assessment at a single institution between June 2013 and December 2016. Mutations were categorized as 1) BRCA1/2 AJ founder mutations (BRCA1 185delAG, BRCA1 5382insC, or BRCA2 6174delT); 2) nonfounder BRCA1/2 mutations; or 3) mutations in non-BRCA1/2 cancer-associated genes.

RESULTS

A total of 732 AJ patients underwent genetic assessment. Of these, 371 patients (51%) had a personal history of breast or ovarian cancer, 540 patients (73.8%) had a family history of breast cancer, and 132 patients (18%) had a family history of ovarian cancer. In the study population, 101 patients (13.8%) were found to have a pathogenic mutation, 78 patients (10.7%) had a BRCA1/2 founder mutation, 3 patients (0.4%) had a nonfounder BRCA1/2 mutation, and 20 patients (2.7%) had a mutation in a non-BRCA1/2 cancer-associated gene. Non-BRCA1/2 cancer-associated genes harboring mutations included RAD51D, TP53, mutS homolog 6 (MSH6), checkpoint kinase 2 (CHEK2), adenomatous polyposis coli (APC), and Fanconi anemia group C protein (FANCC).

CONCLUSIONS

Among AJ patients found to have a pathogenic mutation on genetic assessment, approximately 22.8% had a mutation that would be missed with BRCA1/2 AJ founder mutation testing. Comprehensive multigene panel sequencing can provide clinically relevant genetic information for AJ patients and should be considered for genetic assessment in this population.

Cancer Susceptibility Genetic Testing in a High-Risk Cohort of Urban Ashkenazi Jewish Individuals

Prior to 2013, genetic testing for Ashkenazi Jewish (AJ) individuals primarily consisted of the three-site BRCA1/BRCA2 AJ panel, full sequencing of BRCA1/2, or the Lynch syndrome mismatch repair genes. Multigene panel testing became more widely available in 2013, but limited data are available regarding the impact of multigene panel testing for AJ individuals. Here, we report the frequency of cancer susceptibility gene mutations in a cohort of 427 AJ individuals seen in the Cancer Risk Clinic at The University of Chicago. We found that 29% of affected and 37% of unaffected individuals carried a pathogenic mutation (32% of overall cohort), primarily known familial mutations in BRCA1/2. A minority of mutations were identified in non-BRCA1/2 genes and consisted mainly of AJ founder mutations in CHEK2, APC, and the mismatch repair genes. A panel of AJ founder mutations would have identified the majority (94%) of mutations in clinically actionable genes in both affected and unaffected patients. Based on recent cost-effectiveness studies, offering all AJ individuals a founder mutation panel may be a cost-effective cancer prevention strategy.

No Evidence for the Pathogenicity of the BRCA2 c.6937 + 594T>G Deep Intronic Variant: A Case-Control Analysis

BACKGROUND

The role of deep intronic variants in hereditary cancer susceptibility has been largely understudied. Previously, the BRCA2 c.6937 + 594T>G variant has been shown to preferentially promote the inclusion of a 95 nucleotide cryptic exon and to introduce a premature termination codon. Our objective was to further assess the pathogenicity of the BRCA2 c.6937 + 594T>G deep intronic variant.

PATIENTS AND METHODS

We examined the association between BRCA2 c.6937 + 594T>G and breast cancer (BC) risk in 464 BC cases and 497 noncancer controls from Puerto Rico.

RESULTS

The overall frequency of the G allele was 2.1% in this population. There was no association between the TG/GG genotypes and BC risk in the uncorrected model and after correcting for confounders. There was only one carrier of the GG genotype. This individual did not have personal or family history of cancer and did not meet the National Comprehensive Cancer Network criteria for hereditary cancer genetic testing.

CONCLUSIONS

Although previous work has demonstrated that the BRCA2 c.6937 + 594T>G variant affects splicing, this association study does not support a pathogenic role for the BRCA2 c.6937 + 594T>G intronic variant in breast and ovarian cancer syndrome susceptibility. Furthermore, it emphasizes the need to take into account multiple diverse populations in association studies for the assessment of variant pathogenicity.

Mutational analysis of BRCA1 and BRCA2 genes in Peruvian families with hereditary breast and ovarian cancer

Background

Breast cancer is one of the most prevalent malignancies in the world. In Peru, breast cancer is the second cause of death among women. Five to ten percent of patients present a high genetic predisposition due to BRCA1 and BRCA2 germline mutations.

Methods

We performed a comprehensive analysis of BRCA1 and BRCA2 genes by Sanger sequencing and multiplex ligation‐dependent probe amplification (MLPA) to detect large rearrangements in patients from 18 families, which met the criteria for hereditary breast cancer.

Results

In this series, we found four pathogenic mutations, three previously reported (BRCA1: c.302‐1G>C and c.815_824dup10; BRCA2: c.5946delT) and a duplication of adenines in exon 15 in BRCA1 gene (c.4647_4648dupAA, ClinVar SCV000256598.1). We also found two exonic and four intronic variants of unknown significance and 28 polymorphic variants.

Conclusion

This is the first report to determine the spectrum of mutations in the BRCA1/BRCA2 genes in Peruvian families selected by clinical and genetic criteria. The alteration rate in BRCA1/BRCA2 with proven pathogenic mutation was 22.2% (4 out 18) and this finding could be influenced by the reduced sample size or clinical criteria. In addition, we found three known BRCA1/BRCA2 mutations and a BRCA1 c.4647_4648dupAA as a novel pathogenic mutation.

Early onset breast cancer in Ashkenazi women carriers of founder BRCA1/2 mutations: beyond 10 years of follow-up

This study uncovers disease characteristics by long-term follow-up in Ashkenazi early onset breast cancer (EOBC) patients, carriers of founder BRCA1/2 mutations compared to non-carriers of such mutations. An archives-retrospective design was conducted to study the pathological and clinical characteristics of 149 Ashkenazi Jewish EOBC patients (<42 years) who were referred consecutively to the oncogenetic clinic by the oncology centre at Rambam HealthCare Campus, as from 1995, with a mean follow-up of 13.61 years. Of 149 patients, 33 (22.1%) and 15 (10.1%) carried the founder BRCA1 (185delAG; 5382insC) and BRCA2 (6174delT) mutations, respectively; and 101 (67.8%) were non-carriers of these mutations. Contralateral breast-cancer was predominant among BRCA1/2 carriers compared to non-carriers (14, 58.3%; 6, 60%; 7, 8.1%; respectively, p < .001). Ovarian cancer was diagnosed in two BRCA1 carriers and one non-carrier. Oestrogen and/or progesterone receptor negative tumours were majorly detected in BRCA1 carriers (n = 16, 57.1%) compared to BRCA2 carriers (n = 4, 30.8%) and non-carriers (n = 23, 25.3%) (p = .007). BRCA1 carriers and non-carriers developed contralateral breast cancer at an earlier age than BRCA2 carriers. BRCA2 carriers portrayed similar tumour characteristics to non-carriers. EOBC BRCA1/2 carriers are at risk to develop bilateral disease; however, they are similarly susceptible for local recurrence, distant metastases and mortality.

BRCA1185delAG tumors may acquire therapy resistance through expression of RING-less BRCA1

Heterozygous germline mutations in breast cancer 1 (BRCA1) strongly predispose women to breast cancer. BRCA1 plays an important role in DNA double-strand break (DSB) repair via homologous recombination (HR), which is important for tumor suppression. Although BRCA1-deficient cells are highly sensitive to treatment with DSB-inducing agents through their HR deficiency (HRD), BRCA1-associated tumors display heterogeneous responses to platinum drugs and poly(ADP-ribose) polymerase (PARP) inhibitors in clinical trials. It is unclear whether all pathogenic BRCA1 mutations have similar effects on the response to therapy. Here, we have investigated mammary tumorigenesis and therapy sensitivity in mice carrying the Brca1185stop and Brca15382stop alleles, which respectively mimic the 2 most common BRCA1 founder mutations, BRCA1185delAG and BRCA15382insC. Both the Brca1185stop and Brca15382stop mutations predisposed animals to mammary tumors, but Brca1185stop tumors responded markedly worse to HRD-targeted therapy than did Brca15382stop tumors. Mice expressing Brca1185stop mutations also developed therapy resistance more rapidly than did mice expressing Brca15382stop. We determined that both murine Brca1185stop tumors and human BRCA1185delAG breast cancer cells expressed a really interesting new gene domain-less (RING-less) BRCA1 protein that mediated resistance to HRD-targeted therapies. Together, these results suggest that expression of RING-less BRCA1 may serve as a marker to predict poor response to DSB-inducing therapy in human cancer patients.

Germline BRCA1/2 mutation testing is indicated in every patient with epithelial ovarian cancer: A systematic review

The presence of a germline BRCA1/2 mutation improves options for tailored risk-reducing strategies and treatment in both breast and ovarian cancer patients and their relatives. Currently, referral for germline BRCA1/2 mutation testing of women with epithelial ovarian cancer (EOC) varies widely, based on different criteria, such as age of onset, family history of breast and/or ovarian cancer and histological type of EOC. The overall probability of a germline BRCA1/2 mutation in women with EOC is above 10%, and a substantial part of the germline BRCA1/2 mutation carriers is missed when applying these criteria for referral. Therefore, we strongly recommend referral of all women with EOC for genetic counselling and DNA analysis.

Ovarian Cancer and BRCA1/2 Testing: Opportunities to Improve Clinical Care and Disease Prevention

Without prevention or screening options available, ovarian cancer is the most lethal malignancy of the female reproductive tract. High-grade serous ovarian cancer (HGSOC) is the most common histologic subtype, and the role of germline BRCA1/2 mutation in predisposition and prognosis is established. Given the targeted treatment opportunities with PARP inhibitors, a predictive role for BRCA1/2 mutation has emerged. Despite recommendations to provide BRCA1/2 testing to all women with histologically confirmed HGSOC, uniform implementation remains challenging. The opportunity to review and revise genetic screening and testing practices will identify opportunities, where universal adoption of BRCA1/2 mutation testing will impact and improve treatment of women with ovarian cancer. Improving education and awareness of genetic testing for women with cancer, as well as the broader general community, will help focus much-needed attention on opportunities to advance prevention and screening programs in ovarian cancer. This is imperative not only for women with cancer and those at risk of developing cancer but also for their first-degree relatives. In addition, BRCA1/2 testing may have direct implications for patients with other types of cancers, many of which are now being found to have BRCA1/2 involvement.

Germline BRCA1/2 testing practices in ovarian cancer: Current state and opportunities for new directions

PURPOSE

Given the implications for clinical care and prevention in identifying a BRCA1/2 mutation, the objective of this study was to determine current BRCA1/2 testing practices in ovarian cancer and to identify future directions.

METHODS

Two parallel complementary web-based surveys were sent by email to representatives of Gynecologic Cancer InterGroup (GCIG) and to referral centers in countries with and without GCIG membership. Questions posed addressed indications of BRCA1/2 testing for ovarian cancer; the implication of genetic counseling; and prevention strategies employed.

RESULTS

Among the GCIG, 22 collaborative groups from 19 countries answered the survey. For the complementary survey, 22 referral centers replied. Findings show criteria to offer germline BRCA1/2 testing are mixed; 55% of GCIG members based testing decisions on histology and, among all respondents the main testing criterion remains family history. Typically, genetic counseling is scheduled prior to the genetic testing; however, if negative, results may not be communicated by the genetic counselor. Time between testing and communicating results varies widely between the groups. Lastly, recommendations to relatives regarding risk reduction surgery are inconsistent.

CONCLUSION

Our study highlights the need for collaborative efforts to devise international guidelines around BRCA1/2 testing in ovarian cancer to ensure consistent BRCA1/2 screening practices are adopted. Clinical practice is evolving rapidly and as BRCA1/2 testing is expected to become more widespread, new approaches are required. Coordinating BRCA1/2 testing practices is crucial in terms of care for the patient diagnosed with ovarian cancer but also towards cancer prevention for affected family members.

Recurrent BRCA1 and BRCA2 mutations in Mexican women with breast cancer

BACKGROUND

Germline mutations in the BRCA1 and BRCA2 genes confer an estimated 58% to 80% lifetime risk of breast cancer. In general, screening is done for cancer patients if a relative has been diagnosed with breast or ovarian cancer. There are few data on the prevalence of mutations in these genes in Mexican women with breast cancer and this hampers efforts to develop screening policies in Mexico.

METHODS

We screened 810 unselected women with breast cancer from three cities in Mexico (Mexico City, Veracruz, and Monterrey) for mutations in BRCA1 and BRCA2, including a panel of 26 previously reported mutations.

RESULTS

Thirty-five mutations were identified in 34 women (4.3% of total) including 20 BRCA1 mutations and 15 BRCA2 mutations. Twenty-two of the 35 mutations were recurrent mutations (62.8%). Only five of the 34 mutation carriers had a first-degree relative with breast cancer (three with BRCA1 and two with BRCA2 mutations).

CONCLUSION

These results support the rationale for a strategy of screening for recurrent mutations in all women with breast cancer in Mexico, as opposed to restricting screening to those with a sister or mother with breast or ovarian cancer.

IMPACT

These results will impact cancer genetic testing in Mexico and the identification of at-risk individuals who will benefit from increased surveillance. Cancer Epidemiol Biomarkers Prev; 24(3); 498-505. ©2014 AACR.

Molecular testing for the BRCA1 and BRCA2 Ashkenazi Jewish founder mutations: a report on the College of American Pathologists proficiency testing surveys

PURPOSE

The purpose of this study was to analyze laboratory performance on proficiency testing surveys offered jointly by the College of American Pathologists/American College of Medical Genetics and Genomics biannually for the three common Ashkenazi Jewish founder mutations in the BRCA1 and BRCA2 genes.

METHODS

Survey responses were analyzed for accuracy of genotype determination and the associated clinical interpretation. Data on an individual laboratory's participation over time, number of samples tested, turnaround time, and test methodology were also reviewed.

RESULTS

Between 2003 and 2012, 23 US laboratories and 39 international laboratories participated. There were six genotyping errors, with a corresponding analytical sensitivity of 99.0% (479/484 challenges; 95% confidence interval: 97.6-99.7%) and an analytic specificity of 99.9% (870/871; 95% confidence interval: 99.4-99.9%). Among the 1,325 clinical interpretations, 92.5% (1,226/1,325; 95% confidence interval: 91.0-93.9%) matched the intended response. Most of the 99 discrepancies-81% (80/99)-incorrectly interpreted the risk for a negative test result as having a lifetime risk of breast cancer "that is the same as that in the general population" instead of "that cannot be determined without BRCA mutation testing of the affected relative."

CONCLUSION

Clinical laboratories demonstrated excellent analytical sensitivity and specificity. The clinical interpretation requires additional education, focusing on the clinical interpretation of negative test results for these three mutations.

Recurrent mutation testing of BRCA1 and BRCA2 in Asian breast cancer patients identify carriers in those with presumed low risk by family history

Although the breast cancer predisposition genes BRCA1 and BRCA2 were discovered more than 20 years ago, there remains a gap in the availability of genetic counselling and genetic testing in Asian countries because of cost, access and inaccurate reporting of family history of cancer. In order to improve access to testing, we developed a rapid test for recurrent mutations in our Asian populations. In this study, we designed a genotyping assay with 55 BRCA1 and 44 BRCA2 mutations previously identified in Asian studies, and validated this assay in 267 individuals who had previously been tested by full sequencing. We tested the prevalence of these mutations in additional breast cancer cases. Using this genotyping approach, we analysed recurrent mutations in 533 Malaysian breast cancer cases with <10 % a priori risk, and found 1 BRCA1 (0.2 %) and 5 BRCA2 (0.9 %) carriers. Testing in a hospital-based unselected cohort of 532 Singaporean breast cancer cases revealed 6 BRCA1 (1.1 %) and 3 BRCA2 (0.6 %) carriers. Overall, 2 recurrent BRCA1 and 1 BRCA2 mutations in Malays, 3 BRCA1 and 2 BRCA2 mutations in Chinese and 1 BRCA1 mutation in Indians account for 60, 24 and 20 % of carrier families, respectively. By contrast, haplotype analyses suggest that a recurrent BRCA2 mutation (c.262_263delCT) found in 5 unrelated Malay families has at least 3 distinct haplotypes. Taken together, our data suggests that panel testing may help to identify carriers, particularly Asian BRCA2 carriers, who do not present with a priori strong family history characteristics.

A comparison of the detection of BRCA mutation carriers through the provision of Jewish population-based genetic testing compared with clinic-based genetic testing

BACKGROUND

Guidelines for genetic testing for BRCA1 or BRCA2 stipulate that a personal or family history of cancer is necessary to be eligible for testing. Approximately 2% of Ashkenazi Jewish women carry a mutation, but to date population-based testing has not been advocated. Little is known about the relative yield of a conventional genetic testing programme versus a programme of widespread testing in a population with common founder mutations.

METHODS

We provided both referral-based and Jewish population-based testing between 2008 and 2012. We compared the numbers of BRCA mutation carriers identified through the two streams and estimated the number of genetic counselling hours devoted to each programme.

RESULTS

From 2008 to 2012, 38 female carriers were identified through 487 referrals to our genetics centre (29 unaffected with cancer). During the same time, 6179 Jewish women were tested through our population-based programme and 93 mutation carriers were identified (92 unaffected with cancer). Fewer counsellor hours were devoted to the population-based than to the clinical referral-based testing programme.

CONCLUSION

Genetic testing of all Jewish women above the age of 25 years will greatly expand the number of BRCA mutation carriers identified without a commensurate increase in the number of hours required for counselling.

BRCA genetic testing of individuals from families with low prevalence of cancer: experiences of carriers and implications for population screening

PURPOSE

BRCA genes are associated with hereditary breast and ovarian cancers. Guidelines worldwide currently recommend BRCA genetic testing in asymptomatic individuals only if they belong to "high-risk" families. However, population screening for BRCA1/2 may be the logical next step in populations with a high prevalence of founder mutations, such as Ashkenazi Jews. This study aimed to explore (i) the impact of a positive BRCA genetic test result on individuals who have neither a personal history nor a familial history of cancer and (ii) their attitudes toward the concept of population screening.

METHODS

Semistructured in-depth interviews were carried out with 14 Ashkenazi Jewish women who were asymptomatic BRCA carriers and who belonged to families with low prevalence of cancer.

RESULTS

Three main findings emerged: (i) having no family history of cancer was a source of optimism but also confusion; (ii) engaging in intensified medical surveillance and undergoing preventive procedures was perceived as health-promoting but also tended to induce a sense of physical and psychological vulnerability; and (iii) there was overall support for BRCA population screening, with some reservations.

CONCLUSION

Women belonging to low-cancer-prevalence families within a "high-risk" ethnic community view BRCA genetic testing positively despite the difficulties entailed, because it allows prevention or early detection of cancer. However, implementing a BRCA population screening program should be carried out with proper pre- and post-testing preparation and support for the individuals undergoing testing.

Inherited and acquired alterations in development of breast cancer

Breast cancer is the most common cancer among women, accounting for about 30% of all cancers. In contrast, breast cancer is a rare disease in men, accounting for less than 1% of all cancers. Up to 10% of all breast cancers are hereditary forms, caused by inherited germ-line mutations in "high-penetrance," "moderate-penetrance," and "low-penetrance" breast cancer susceptibility genes. The remaining 90% of breast cancers are due to acquired somatic genetic and epigenetic alterations. A heterogeneous set of somatic alterations, including mutations and gene amplification, are reported to be involved in the etiology of breast cancer. Promoter hypermethylation of genes involved in DNA repair and hormone-mediated cell signaling, as well as altered expression of micro RNAs predicted to regulate key breast cancer genes, play an equally important role as genetic factors in development of breast cancer. Elucidation of the inherited and acquired genetic and epigenetic alterations involved in breast cancer may not only clarify molecular pathways involved in the development and progression of breast cancer itself, but may also have an important clinical and therapeutic impact on improving the management of patients with the disease.

Germline mutations of BRCA1 and BRCA2 genes in Turkish breast, ovarian, and prostate cancer patients

Distribution and prevalence of germline mutations in BRCA1 and BRCA2 differ among different populations. For the Turkish population, several studies have addressed high-risk breast cancer and ovarian cancer (BC-OC) patients. In most studies, both genes were analyzed in part, and a quite heterogeneous mutation spectrum was observed. For high-risk Turkish prostate cancer (PCa) patients, however, there are no data available about mutations of germline BRCA genes. To accurately determine the contribution of germline mutations in BRCA1 and BRCA2 in Turkish BC, OC, and PCa high-risk patients, 106 high-risk BC-OC patients, 50 high-risk PCa patients, and 50 control subjects were recruited. The study represents the only full screening, to date, of a large series of Turkish high-risk BC-OC patients and the only study in Turkish high-risk PCa patients. Mutation screenings were performed on coding exons of both genes with either denaturing gradient gel electrophoresis or denaturing high performance liquid chromatography, or with both techniques. Three deleterious mutations in BRCA1 and three deleterious mutations in BRCA2 were detected in different BC-OC patients, and one truncating mutation was detected in a high-risk PCa patient. In addition, 28 different unclassified and mostly novel variants were detected in both genes, as well as several silent polymorphisms. These findings reflect the genetic heterogeneity of the Turkish population and are relevant to genetic counseling and clinical management.

Founder BRCA1/2 mutations in the Europe: implications for hereditary breast-ovarian cancer prevention and control

Detection of mutations in hereditary breast and ovarian cancer-related BRCA1 and BRCA2 genes is an effective method of cancer prevention and early detection. Different ethnic and geographical regions have different BRCA1 and BRCA2 mutation spectrum and prevalence. Along with the emerging targeted therapy, demand and uptake for rapid BRCA1/2 mutations testing will increase in a near future. However, current patients selection and genetic testing strategies in most countries impose significant lag in this practice. The knowledge of the genetic structure of particular populations is important for the developing of effective screening protocol and may provide more efficient approach for the individualization of genetic testing. Elucidating of founder effect in BRCA1/2 genes can have an impact on the management of hereditary cancer families on a national and international healthcare system level, making genetic testing more affordable and cost-effective. The purpose of this review is to summarize current evidence about the BRCA1/2 founder mutations diversity in European populations.

BRCA1 and BRCA2 germline mutation analysis among Indian women from south India: identification of four novel mutations and high-frequency occurrence of 185delAG mutation

Mutations in the BRCA1 and BRCA2 genes profoundly increase the risk of developing breast and/or ovarian cancer among women. To explore the contribution of BRCA1 and BRCA2 mutations in the development of hereditary breast cancer among Indian women, we carried out mutation analysis of the BRCA1 and BRCA2 genes in 61 breast or ovarian cancer patients from south India with a positive family history of breast and/or ovarian cancer. Mutation analysis was carried out using conformation-sensitive gel electrophoresis (CSGE) followed by sequencing. Mutations were identified in 17 patients (28.0%); 15 (24.6%) had BRCA1 mutations and two (3.28%) had BRCA2 mutations. While no specific association between BRCA1 or BRCA2 mutations with cancer type was seen, mutations were more often seen in families with ovarian cancer. While 40% (4/10) and 30.8% (4/12) of families with ovarian or breast and ovarian cancer had mutations, only 23.1% (9/39) of families with breast cancer carried mutations in the BRCA1 and BRCA2 genes. In addition, while BRCA1 mutations were found in all age groups, BRCA2 mutations were found only in the age group of < or =40 years. Of the BRCA1 mutations, there were three novel mutations (295delCA; 4213T-->A; 5267T-->G) and three mutations that have been reported earlier. Interestingly, 185delAG, a BRCA1 mutation which occurs at a very high frequency in Ashkenazi Jews, was found at a frequency of 16.4% (10/61). There was one novel mutation (4866insT) and one reported mutation in BRCA2. Thus, our study emphasizes the importance of mutation screening in familial breast and/or ovarian cancers, and the potential implications of these findings in genetic counselling and preventive therapy.

The contribution of BRCA1 and BRCA2 to ovarian cancer

Germline mutations of the BRCA1 and BRCA2 genes confer a high life-time risk of ovarian cancer. They represent the most significant and well characterised genetic risk factors so far identified for the disease. The frequency with which BRCA1/2 mutations occur in families containing multiple cases of ovarian cancer or breast and ovarian cancer, and in population-based ovarian cancer series varies geographically and between different ethnic groups. There are differences in the frequency of common mutations and in the presence of specific founder mutations in different populations. BRCA1 and BRCA2 are responsible for half of all families containing two or more ovarian cancer cases. In population-based studies, BRCA1 and BRCA2 mutations are present in 5-15% of all ovarian cancer cases. Often, individuals in which mutations are identified in unselected cases have no family history of either ovarian or breast cancer. The ability to identify BRCA1/2 mutations has been one of the few major success stories over the last few years in the clinical management of ovarian cancer. Currently, unaffected individuals can be screened for mutations if they have a family history of the disease. If a mutation is identified in the family, and if an individual is found be a mutation carrier, they can be offered clinical intervention strategies that can dramatically reduce their ovarian cancer risks. In some populations with frequent founder mutations screening may not be dependent on whether a mutation is identified in an affected relative.

The relative contribution of point mutations and genomic rearrangements in BRCA1 and BRCA2 in high-risk breast cancer families

The demand for BRCA1 and BRCA2 mutation screening is increasing as their identification will affect medical management. However, both the contribution of different mutation types in BRCA1 and BRCA2 and whom should be offered testing for large genomic rearrangements have not been well established in the U.S. high-risk population. We define the prevalence and spectrum of point mutations and genomic rearrangements in BRCA genes in a large U.S. high-risk clinic population of both non-Ashkenazi and Ashkenazi Jewish descent, using a sample set representative of the U.S. genetic testing population. Two hundred fifty-one probands ascertained through the University of Pennsylvania high-risk clinic, all with commercial testing for BRCA1 and BRCA2, with an estimated prevalence of BRCA mutation >or=10% using the Myriad II model and a DNA sample available, were studied. Individuals without deleterious point mutations were screened for genomic rearrangements in BRCA1 and BRCA2. In the 136 non-Ashkenazi Jewish probands, 36 (26%) BRCA point mutations and 8 (6%) genomic rearrangements (7 in BRCA1 and 1 in BRCA2) were identified. Forty-seven of the 115 (40%) Ashkenazi Jewish probands had point mutations; no genomic rearrangements were identified in the group without mutations. In the non-Ashkenazi Jewish probands, genomic rearrangements constituted 18% of all identified BRCA mutations; estimated mutation prevalence (Myriad II model) was not predictive of their presence. Whereas these findings should be confirmed in larger sample sets, our data suggest that genomic rearrangement testing be considered in all non-Ashkenazi Jewish women with an estimated mutation prevalence >or=10%.

Clinical outcomes of breast cancer in carriers of BRCA1 and BRCA2 mutations

BACKGROUND

Some features of breast cancer in women with a BRCA1 mutation suggest that hereditary breast cancer has a poor outcome. We conducted a national population-based study of Israeli women to determine the influence, if any, of a BRCA1 or a BRCA2 mutation on the prognosis in breast cancer.

METHODS

We obtained data on all incident cases of invasive breast cancer that were diagnosed from January 1, 1987, to December 31, 1988, and recorded in the Israel National Cancer Registry. We requested a paraffin-embedded tumor block or an unstained slide and the corresponding pathological and clinical records for all such cases. DNA extracted from the tumor specimens was analyzed for the three founder mutations in BRCA1 and BRCA2. For each subject, available pathological and oncologic records were reviewed.

RESULTS

We were able to retrieve a pathological sample from 1794 of 2514 subjects (71%). Among those women, we obtained medical records for 1545 (86%). A BRCA1 or BRCA2 mutation was identified in 10% of the women who were of Ashkenazi Jewish ancestry. The adjusted hazard ratios for death from breast cancer were not significantly different among mutation carriers and noncarriers (hazard ratio among BRCA1 carriers, 0.76; 95% confidence interval [CI], 0.45 to 1.30; P=0.31; hazard ratio among BRCA2 carriers, 1.31; 95% CI, 0.80 to 2.15; P=0.28). Among women who were treated with chemotherapy, the hazard ratio for death among BRCA1 carriers was 0.48 (95% CI, 0.19 to 1.21; P=0.12).

CONCLUSIONS

Breast cancer-specific rates of death among Israeli women are similar for carriers of a BRCA founder mutation and noncarriers.

Risk assessment and genetic counseling for hereditary breast and ovarian cancer: recommendations of the National Society of Genetic Counselors

These cancer genetic counseling recommendations describe the medical, psychosocial and ethical implications of identifying at-risk individuals for hereditary breast and ovarian cancer (HBOC) through cancer risk assessment, with or without genetic susceptibility testing. They were developed by members of the Practice Issues Subcommittee of the National Society of Genetic Counselors' Familial Cancer Risk Counseling Special Interest Group. The information contained in this document is derived from extensive review of the current literature on cancer genetic risk assessment as well as the professional expertise of genetic counselors with significant experience in education and counseling regarding hereditary breast and ovarian cancer. Critical components of the process include the ascertainment of medical and family histories, determination and communication of cancer risk, assessment of risk perception, education regarding the genetics of HBOC, discussion of molecular testing for HBOC if appropriate (including benefits, risks and limitations) and any necessary follow-up. These recommendations do not dictate an exclusive course of management or guarantee a specific outcome. Moreover, they do not replace the professional judgment of a health care provider based on the clinical situation of a client.

Cancer risks in carriers of the BRCA1/2 Ashkenazi founder mutations

BACKGROUND

The risks for cancers other than breast (BC) or ovarian (OC) cancer in breast cancer gene 1 and 2 (BRCA1/2) mutation carriers were elevated in studies of carrier families. However, case-control studies did not confirm this observation.

OBJECTIVE

To compare the risks for other cancers in BRCA1/2 mutation carriers and non-carriers, all affected with BC and/or OC. Both groups share risk modifiers of BC/OC, which enabled assessment of the role of BRCA1/2 mutations.

METHODS

1098 Ashkenazi Jewish women affected with BC and/or OC were ascertained during 1995-2003; molecular testing revealed 229 BRCA1 and 100 BRCA2 carriers and 769 non-carriers. COX proportional hazard models were used to evaluate the risk of other cancers. Analyses were conducted including all other cancers or only those diagnosed after BC/OC diagnosis.

RESULTS

The HRs for any other cancer were 2.6 (95% CI 1.7 to 4.2, p<0.001) and 1.8 (95% CI 0.95 to 3.6, p = 0.07) in BRCA1 and BRCA2 carriers, respectively. The corresponding colon cancer HRs were 3.9 (95% CI 1.3 to 12.1, p = 0.02) and 2.3 (95% CI 0.5 to 11.3, p = 0.3) in BRCA1 and BRCA2 carriers. The HR for lymphoma was 11.9 (95% CI 3.1 to 46.2, p = 0.001) in BRCA2 carriers. Risk estimates for other cancers after the onset of BC/OC were similar.

CONCLUSION

A 2.5-fold increase in any other cancer and a fourfold risk of colon cancer were found among BRCA1 carriers. The corresponding HRs in BRCA2 carriers were non-significant, except for the markedly elevated risk of lymphoma. These results suggest a role for BRCA1/2 mutations in colorectal cancer risk in a subgroup of BC/OC-affected carriers.

High frequency of BRCA1 5382insC mutation in Russian breast cancer patients

BRCA1 5382insC variant was repeatedly detected in Jewish breast cancer (BC) families residing in USA and Israel as well as in non-Jewish familial BC patients from Poland, Latvia, Hungary, Russia and some other European countries. However, the distribution of BRCA1 5382insC mutation in unselected BC cases vs. controls has been systematically investigated mainly in Ashkenazi Jews. Here we applied a case-control study design in order to evaluate the impact of BRCA1 5382insC allele on BC incidence in St Petersburg, Russia. High frequency of the BRCA1 5382insC allele was detected in a group of bilateral breast cancer patients (10.4%; 15/144). Randomly selected unilateral BC cases demonstrated noticeable occurrence of BRCA1 5382insC mutation as well (3.7%; 32/857), with evident excess of the carriers in the early-onset (40 years) category (6.1%; 6/99) and in patients reporting breast and/or ovarian tumours in first-degree relatives (11.3%; 11/97). Strikingly, none of 478 middle-aged controls and 344 elderly tumour-free women carried the 5382insC variant. The presented data confirm a noticeable contribution of BRCA1 5382insC mutation in BC development in Russia, that may justify an extended BRCA1 5382insC testing within this population.

BRCA1 and BRCA2 mutations in a South American population

A sample of 64 high-risk breast and/or ovarian cancer families from Chile were screened for germline mutations in the coding sequences and exon-intron boundaries of BRCA1 (MIN no. 113705) and BRCA2 (MIN no. 600185) genes using conformation-sensitive gel electrophoresis, and the mutations found were confirmed with direct sequencing. Seven families (10.9%) were found to carry BRCA1 mutations and three families (4.7%) had BRCA2 mutations. Six different pathogenic mutations were detected in BRCA1, four that had been reported previously (c.187_188delAG; c.300T-->G, c.3450_3453delCAAG and IVS17-1G-->A) and two novel mutations (c.2605_2606delTT and c.4185_4188delCAAG). In BRCA2, we found three different pathogenic mutations, two previously described (c.6174delT and c.6503_6504delTT) and one novel mutation (c.5667delT). We also identified nine variants of unknown significance (five in BRCA1 and four in BRCA2). These findings indicate that the Chilean population has a heterogeneous spectrum of prevalent BRCA mutations. Given the results obtained in our study, the screening of the entire BRCA1 and BRCA2 coding regions is necessary for the molecular genetic testing of Chilean high-risk breast/ovarian cancer patients. To our knowledge, this is the first genetic study of BRCA gene mutations conducted in Chile. The Chilean population has a well-known admixed Amerindian-Caucasian ratio and, therefore, our findings are not only important per se, but they constitute the basis for improved and more specific genetic counselling, as well as to support for preventive campaigns geared toward the Chilean population.

Localization of breast cancer susceptibility loci by genome-wide SNP linkage disequilibrium mapping

We studied the feasibility of a novel approach to localize breast cancer susceptibility genes, using a low-density genome-wide panel of single-nucleotide polymorphisms and taking advantage of large regions of linkage disequilibrium (LD) flanking Jewish disease genes in high-risk cases. With Affymetrix GeneChip arrays, we genotyped 8,576 polymorphisms in three sets of Ashkenazi Jewish breast cancer cases: a "validation" set of 27 breast cancer cases, all of whom carried the BRCA2*6174delT founder mutation; a "field" set of 19 breast cancer cases from male breast cancer kindreds, which simulated conditions for finding new genes; and a "test" set of 57 probands from breast cancer kindreds (4 or more cases/kindred), in which mutations in BRCA1 and BRCA2 had been excluded. To identify associations, we compared the frequency of genotypes and haplotypes in cases vs. controls by the Fisher's exact test and a maximum likelihood ratio test. In the "validation" set, we demonstrated the presence of a region of linkage disequilibrium on BRCA2*6174delT chromosomes that spanned over 5 million bases. In the "field" set, we showed that this large region of linkage disequilibrium flanking BRCA2 was detectable despite the presence of heterogeneity in the sample set. Finally, in the "test" set, at least three regions of interest emerged that could contain novel breast cancer genes, one of which had been identified previously by linkage analysis. While these results demonstrate the feasibility of genome-wide association strategies, further application of this approach will critically depend on optimizing the density and distribution of SNPs and the size and type of study design.

Assessing BRCA Carrier Probabilities in Extended Families

Purpose

Carrier prediction models estimate the probability that a person has a BRCA mutation. We evaluated the accuracy of the BOADICEA model and compared its performance with that of other models (BRCAPRO, Myriad I and II, Couch, and Manchester Scoring System). We also studied the effect of extended family information on risk estimation using BOADICEA.

Methods

We compared the area under receiver operating characteristic curves generated from 472 families with one member tested for BRCA mutations. We calculated sensitivity, specificity, and predictive values at an estimated probability of 10% and explored the biases of carrier prediction.

Results

BOADICEA performed better than the other models in Ashkenazi Jewish (AJ) families, BRCAPRO performed slightly better in non-AJ families, and Myriad II performed comparably well in both groups. Including extended family information in BOADICEA yielded slightly better performance than did limiting the information to second-degree relatives. Using a 10% cutoff point, BOADICEA and Myriad II were most sensitive in predicting BRCA1/2 mutations in AJ families, and Myriad II was most sensitive in non-AJ families. The Manchester Scoring System was the most sensitive and least specific in a subgroup of non-AJ families. BOADICEA and BRCAPRO tended to underestimate the observed risk at low estimated probabilities and overestimate it at higher probabilities.

Conclusion

The BOADICEA, BRCAPRO, and Myriad II models performed similarly. Including second-degree relatives slightly improved carrier prediction by BOADICEA. The Myriad II model was the easiest to implement.

Clinical implications of the breast cancer susceptibility genes BRCA1 and BRCA2

Genetic testing for BRCA1 and BRCA2 mutations has become an important part of the practice of medical oncology and clinical genetics over the past decade. Increasing numbers of women are requesting a genetic test so that they may better understand their personal risks of breast and ovarian cancer, and so that they may take appropriate measures to reduce the risk. Several of the risk factors can be modified, including breastfeeding and the use of oral contraceptives. A significant number of women opt for preventive mastectomy or oophorectomy, which will dramatically reduce the risks of breast and ovarian cancer. Chemoprevention with tamoxifen is still uncommon, largely due to women's fears of the side effects of the drug. A number of studies have shown that magnetic resonance imaging is superior to conventional mammography in terms of the early detection of breast cancer in the high-risk population. This article explores what is known about assessing genetic risk and the evidence supporting a range of preventive strategies.

Cyclin E expression in breast cancer: predicting germline BRCA1 mutations, prognosis and response to treatment

BACKGROUND

Elevated levels of the cell cycle protein cyclin E, and low levels of its inhibitor, p27(Kip1), have been associated with a poor prognosis following breast cancer. Some studies have found that germline mutations in the breast cancer susceptibility gene, BRCA1, are also associated with an inferior survival rate. The relationship between cyclin E/p27(Kip1) levels, BRCA1 status and outcome has not been studied in detail.

PATIENTS AND METHODS

We analyzed a historical cohort of 288 Ashkenazi Jewish women who were diagnosed with breast cancer between 1980 and 1995 and were previously tested for BRCA1/2 mutations. Protein levels of cyclin E and p27(Kip1) were assessed by immunohistochemistry. Breast cancer-specific survival (BCSS) was the main outcome measured.

RESULTS

The median follow-up was 8 years. Thirty tumors carried germline BRCA1 mutations. These tumors were more likely to have high cyclin E protein levels [odds ratio (OR) 9.5; P <0.001] and low p27(Kip1) protein levels (OR 2.8; P=0.03) than tumors from patients without BRCA1/2 mutations. High cyclin E expression level was the strongest predictor of BRCA1 germline mutations (multivariate OR 4.7; P=0.004). On univariate analysis, high cyclin E protein levels [relative risk (RR) 2.6; P <0.001] and low p27(Kip1) protein levels (RR 2.3; P=0.006) were significant prognostic factors for a poorer BCSS. In Cox multivariate models, high cyclin E levels remained an independent indicator of poor outcome only in the subgroup of patients who did not receive chemotherapy (P=0.002).

CONCLUSIONS

In this ethnically restricted cohort, a high level of cyclin E is a characteristic of BRCA1-related breast cancer, and is a marker of poor prognosis following breast cancer, particularly in the absence of adjuvant chemotherapy.

Cancer genetics in primary care

The cloning of two major breast cancer susceptibility genes, BRCA1 and BRCA2, in 1994 and 1995 and the subsequent development of commercial genetic testing has brought hereditary cancer genetics into the public eye. In addition to DNA-based genetic testing, new strategies and treatments have been developed to provide accurate assessment of cancer risk and to reduce the chances of cancer developing in the future. This increasing scientific and public attention has prompted some cancer patients and their families to find out whether they "have the cancer gene" and has placed more responsibility on primary care clinicians to identify people who should be referred for specialized services of hereditary cancer genetics.

BRCA1 and BRCA2: 1994 and beyond

The discovery of the first gene associated with hereditary breast cancer, BRCA1, was anticipated to greatly increase our understanding of both hereditary and sporadic forms of breast cancer, and to lead to therapeutic and preventive breakthroughs. Much has been learned during the past decade about the genetic epidemiology of breast cancer, the ethnic distribution and clinical consequences of BRCA1 and BRCA2 mutations, and the central role of DNA repair in breast cancer susceptibility. The ability to translate this knowledge into novel treatments, however, remains elusive.