Evidence for a BRCA1 founder mutation in families of West African ancestry

Gynecologic Care of Black Breast Cancer Survivors

Purpose of Review

Black patients suffer from breast cancer-related racial health disparities, which could have implications on their gynecologic care. This review explores considerations in the gynecologic care of Black breast cancer survivors.

Recent Findings

Black people have a higher risk of leiomyoma and endometrial cancer, which could confound bleeding patterns such as in the setting of tamoxifen use. As Black people are more likely to have early-onset breast cancer, this may have implications on long-term bone and heart health. Black patients may be more likely to have menopausal symptoms at baseline and as a result of breast cancer treatment. Furthermore, Black patients are less likely to utilize assisted reproductive technology and genetic testing services.

Summary

It is important for healthcare providers to be well-versed in the intersections of breast cancer and gynecologic care. Black breast cancer survivors may have unique considerations for which practitioners should be knowledgeable.

A Public Health Emergency: Breast Cancer Among Black Communities in the United States

While Black people have a similar incidence of breast cancer compared to White people, they have a 40% increased death rate. Black people are more likely to be diagnosed with aggressive subtypes such as triple-negative breast cancer. However, despite biological factors, systemic racism and social determinants of health create delays in care and barriers to treatment. While genetic testing holds incredible promise for Black people, uptake remains low and results may be challenging to interpret. There is a need for more robust, multidisciplinary, and antiracist interventions to reverse breast cancer-related racial disparities.

Founder vs. non-founder BRCA1/2 pathogenic alleles: the analysis of Belarusian breast and ovarian cancer patients and review of other studies on ethnically homogenous populations

The spectrum of BRCA1/2 mutations demonstrates significant interethnic variations. We analyzed for the first time the entire BRCA1/2 coding region in 340 Belarusian cancer patients with clinical signs of BRCA1/2-related disease, including 168 women with bilateral and/or early-onset breast cancer (BC), 104 patients with ovarian cancer and 68 subjects with multiple primary malignancies involving BC and/or OC. BRCA1/2 pathogenic alleles were detected in 98 (29%) women, with 67 (68%) of these being represented by founder alleles. Systematic comparison with other relevant studies revealed that the founder effect observed in Belarus is among the highest estimates observed worldwide. These findings are surprising, given that the population of Belarus did not experience geographic or cultural isolation throughout history.

Hereditary variants of unknown significance in African American women with breast cancer

Expanded implementation of genetic sequencing has precipitously increased the discovery of germline and somatic variants. The direct benefit of identifying variants in actionable genes may lead to risk reduction strategies such as increased surveillance, prophylactic surgery, as well as lifestyle modifications to reduce morbidity and mortality. However, patients with African ancestry are more likely to receive inconclusive genetic testing results due to an increased number of variants of unknown significance decreasing the utility and impact on disease management and prevention. This study examines whole exome sequencing results from germline DNA samples in African American women with a family history of cancer including 37 cases that were diagnosed with breast cancer and 51 family members. Self-identified ancestry was validated and compared to the 1000 genomes population. The analysis of sequencing results was limited to 85 genes from three clinically available common genetic screening platforms. This target region had a total of 993 variants of which 6 (<1%) were pathogenic or likely pathogenic, 736 (74.1%) were benign, and 170 (17.1%) were classified as a variant of unknown significance. There was an average of 3.4±1.8 variants with an unknown significance per individual and 85 of 88 individuals (96.6%) harbored at least one of these in the targeted genes. Pathogenic or likely pathogenic variants were only found in 6 individuals for the BRCA1 (p.R1726fs, rs80357867), BRCA2 (p.K589fs, rs397507606 & p.L2805fs, rs397507402), RAD50 (p.E995fs, rs587780154), ATM (p.V2424G, rs28904921), or MUTYH (p.G396D, rs36053993) genes. Strategies to functionally validate the remaining variants of unknown significance, especially in understudied and hereditary cancer populations, are greatly needed to increase the clinical utility and utilization of clinical genetic screening platforms to reduce cancer incidence and mortality.

Screening of BRCA1/2 variants in Mauritanian breast cancer patients

Background and study aim

Carrying a pathogenic BRCA1/2 variant increases greatly young women’s risk of developing breast cancer (BC). This study aimed to provide the first genetic data on BC in Mauritania.

Methods

Using NGS based screening; we searched for BRCA1/2 variants in DNA samples from 137 patients diagnosed for hereditary BC.

Results

We identified 16 pathogenic or likely pathogenic (PV) variants carried by 38 patients. Two predominant BRCA1 PV variants were found: c.815_824dup and c.4986 + 6 T > C in 13 and 7 patients, respectively. Interestingly, three novels BRCA1/2 predicted pathogenic variants have also been detected. Notably, no specific distribution of BRCA1/2 variants was observed regarding triple negative breast cancer (TNBC) or patient gender status.

Conclusions

In this first genetic profiling of BC in Mauritania, we identified a substantial number of BRCA1/2 pathogenic variants. This finding could be important in the future diagnosis and prevention policy of hereditary BC in Mauritania.

New Insights Into c.815_824dup Pathogenic Variant of BRCA1 in Inherited Breast Cancer: A Founder Mutation of West African Origin

Founder mutations have been reported in BRCA1 and BCRA2 in different ethnic groups with inherited breast cancer. Testing of targeted mutations in specific populations is important for cancer prevention in mutation carriers. In Sub-Saharan Africa, only a few studies have reported specific founder mutations in inherited breast cancer. The pathogenic variant c.815_824dup of BRCA1 has been reported as the most frequent among African American populations with inherited breast cancer and was supposed to have a West African origin. Recent report from Senegal identified this variant in women with inherited breast cancer at the highest frequency ever reported. The variant was linked to a common haplotype confirming its founder effect in West Africa. In this article, we review the mutation history of c.815_824dup and discuss how it spread out of Africa through the transatlantic slave trade.

Breast cancer in West Africa: molecular analysis of BRCA genes in early-onset breast cancer patients in Burkina Faso

BACKGROUND

Breast cancer (BC) is the most commonly diagnosed cancer and the second leading cause of cancer-related deaths among women in Africa after cervical cancer. Even if the epidemiological data are now aligned with those relating to industrialized countries, the knowledge concerning breast cancer in Africa, particularly in Western Africa, still lack clinical data, medical treatments, and the evaluation of genetic and non-genetic factors implicated in the etiology of the disease. The early onset and the aggressiveness of diagnosed breast cancers in patients of African ancestry strongly suggest that the genetic risk factor may be a key component, but so far, very few studies on the impact of germ line mutations in breast cancer in Africa have been conducted, with negative consequences on prevention, awareness and patient management. Through Next Generation sequencing (NGS), we analyzed all of the coding regions and the exon-intron junctions of BRCA1 and BRCA2 genes-the two most important genes in hereditary breast cancer-in fifty-one women from Burkina Faso with early onset of breast cancer with or without a family history.

RESULTS

We identified six different pathogenic mutations (three in BRCA1, three in BRCA2), two of which were recurrent in eight unrelated women. Furthermore, we identified, in four other patients, two variants of uncertain clinical significance (VUS) and two variants never previously described in literature, although one of them is present in the dbSNP database.

CONCLUSIONS

This is the first study in which the entire coding sequence of BRCA genes has been analyzed through Next Generation Sequencing in Burkinabe young women with breast cancer. Our data support the importance of genetic risk factors in the etiology of breast cancer in this population and suggest the necessity to improve the genetic cancer risk assessment. Furthermore, the identification of the most frequent mutations of BRCA1 and BRCA2 in the population of Burkina Faso will allow the development of an inexpensive genetic test for the identification of subjects at high genetic cancer risk, which could be used to design personalized therapeutic protocols.

Founder variants and population genomes-Toward precision medicine

Human migration and community specific cultural practices have contributed to founder events and enrichment of the variants associated with genetic diseases. While many founder events in isolated populations have remained uncharacterized, the application of genomics in clinical settings as well as for population scale studies in the recent years have provided an unprecedented push towards identification of founder variants associated with human health and disease. The discovery and characterization of founder variants could have far reaching implications not only in understanding the history or genealogy of the disease, but also in implementing evidence based policies and genetic testing frameworks. This further enables precise diagnosis and prevention in an attempt towards precision medicine. This review provides an overview of founder variants along with methods and resources cataloging them. We have also discussed the public health implications and examples of prevalent disease associated founder variants in specific populations.

Evidence for an ancient BRCA1 pathogenic variant in inherited breast cancer patients from Senegal

BRCA1 and BRCA2 are the most incriminated genes in inherited breast/ovarian cancers. Several pathogenic variants of these genes conferring genetic predisposition have been described in different populations but rarely in sub-Saharan Africa. The objectives of this study were to identify pathogenic variants of the BRCA genes involved in hereditary breast cancer in Senegal and to search for a founder effect. We recruited after free informed consent, 27 unrelated index cases diagnosed with breast cancer and each having a family history. Mutation screening of the genes identified a duplication of ten nucleotides c.815_824dupAGCCATGTGG, (p.Thr276Alafs) (NM_007294.3) located in exon 11 of BRCA1 gene, in 15 index cases (allelic frequency 27.7%). The pathogenic variant has been previously reported in African Americans as a founder mutation of West African origin. Haplotypes analysis of seven microsatellites surrounding the BRCA1 gene highlights a shared haplotype encompassing ~400 kb between D17S855 and D17S1325. This haplotype was not detected in none of 15 healthy controls. Estimation of the age of the pathogenic variant suggested that it occurred ~1400 years ago. Our study identified a founder pathogenic variant of BRCA1 predisposing to breast cancer and enabled the establishment of an affordable genetic test as a mean of prevention for Senegalese women at risk.

Identification of BRCA1/2 p.Ser1613Gly, p.Pro871Leu, p.Lys1183Arg, p.Glu1038Gly, p.Ser1140Gly, p.Ala2466Val, p.His2440Arg variants in women under 45 years old with breast nodules suspected of having breast cancer in Burkina Faso

Breast cancer is the top cause of cancer mortality among women in the world and the second in Africa. The aims of this study were to: i) identify women with breast nodules suspected of having breast cancer ii) sequence the BRCA1 and BRCA2 genes and iii) screen mutations. From 2015 to 2016, 112 women aged from 35 to 44 years, who had come for consultation in the gynecology/obstetrics and the oncology department of the University Hospital Yalgado Ouedraogo, voluntarily agreed to participate to this study. Whole blood was collected from those with mammary nodules. The genomic DNA was extracted using Qiagen kit. FAST KAPA was used for genomic DNA amplification and the purified PCR products were analyzed by direct sequencing using Big Dye v1.1 and ABI 3730 automated sequencer. Nucleotides substitutions were determined. We identified BRCA1 SNPs rs1799966, rs799917, rs16942, rs16941, rs2227945, and BRCA2 SNPs rs169547, rs4986860. These identified variants are found mostly in cases of benign tumors of breast or ovarian cancer with familial history of breast cancer. This study in Burkina-Faso, is the basis for improved and more specific genetic testing, and suggests that additional genes contributing to an increased risk of breast cancer should be analyzed.

Breast Cancer Disparities: How Can We Leverage Genomics to Improve Outcomes?

Breast cancer mortality rates are higher in African American compared with white American women. Disproportionately rising incidence rates, coupled with higher rates of biologically aggressive disease among African Americans is resulting in a widening of the mortality disparity. Higher rates of triple-negative breast cancer among African American women, as well as women from western sub-Saharan Africa, has prompted questions regarding the role of African ancestry as a marker of hereditary susceptibility for specific disease phenotypes. Advances in germline genetics, as well as somatic tumor genomic research, hold great promise in the effort to understand the biology of breast cancer variations between different population subsets.

BRCA1 c.68_69delAG (exon2), c.181T>G (exon5), c.798_799delTT and 943ins10 (exon11) mutations in Burkina Faso

The worldwide variation of BRCA mutations is well known. The c.68_69delAG, c.181T>G, c.798_799delTT mutations in BRCA1 were observed in Moroccan, Algerian and Tunisian Breast Cancer families and were described founder mutation in Northern Africa. The 943ins10 is also recognized a founder mutation in West Africa. To our knowledge no study has been published on BRCA1/2 germline mutations and hereditary breast cancer (HBC) in population of Burkina Faso. The aim of the present study (first in Burkina Faso) was to screen for these four mutations in 15 unrelated patients with HBC. Mutation analysis was performed by Sanger sequencing of coding exon2, Exon5 and exon11A sequences of the BRCA1 gene. Blood specimens of 15 patients from Burkina Faso, with HBC were collected at the University Hospital Yalgado OUEDRAOGO (CHU-YO) of Ouagadougou in Burkina Faso. c.68_69delAG (exon2), c.181T>G (exon5), c.798_799delTT and 943ins10 (exon11) mutations were not detected in any of the 15 women diagnosed with family breast cancer history. Genetic analysis in this study, we show that targeting relevant exons in BRCA1 genes did not allow detection of mutations in the population of Burkina Faso. Therefore, such an approach may be of interest to perfom a complete sequencing of BRCA1 and BRCA2 genes in families at a high risk of developing breast cancer in Burkina Faso.

Haplotype analysis of BRCA1 intragenic markers in Iranian patients with familial breast and ovarian cancer

BACKGROUND

Breast cancer is the most common malignancy in women. Breast Cancer Type 1 Susceptibility gene (BRCA1) is a tumor suppressor gene, involved in DNA damage repair and in 81% of the breast-ovarian cancer families were due to BRCA1. In some clinically investigated genes, the intragenic marker polymorphism is important and the screening of such mutations is faster by using short tandem repeat (STR) polymorphism. Individual polymorphism of STR is a good evidence for following inheritance of repeat polymorphism.

OBJECTIVE

The aim of this study was to evaluate three intragenic BRCA1 marker polymorphisms in families, which have two or more patients with breast/ovarian cancer in comparison to healthy women.

MATERIALS AND METHODS

A total of 107 breast and/or ovarian cancer patients and 93 unrelated healthy women with no clinical phenotype of any malignancy or familial cancer history constitute the study groups. Haplotyping analysis, at 3 intragenic BRCA1 microsatellite markers (D17S855, D17S1322 and D17S1323), were performed for all subject and control groups using labeled primers.

RESULTS

After fragment analysis, significance differences were observed as follows: two alleles of D17S855; allele 146 (p=0.02) and 150 (p=0.006), and two alleles of D17S1322, allele 121 (p=0.015) and 142 (p=0.043). These differences were compared with control group. There was significance difference in 8 di/tri allelic haplotypes in present experimental subjects. Some haplotypes were observed to have approximately twice the relation risk for breast cancer.

CONCLUSION

According to recent results, assessment of presence or absence of mentioned alleles in BRCA1 microsatellite can be used for prognosis in individuals, suspected of having or not having the breast cancer.

The spectrum of BRCA1 and BRCA2 alleles in Latin America and the Caribbean: a clinical perspective

Hereditary cancer predisposition gene testing allows the identification of individuals at high risk of cancer that may benefit from increased surveillance, chemoprevention, and prophylactic surgery. In order to implement clinical genetic strategies adapted to each population's needs and intrinsic genetic characteristic, this review aims to present the current status of knowledge about the spectrum of BRCA pathogenic variants in Latin American populations. We have conducted a comprehensive review of 33 studies published between 1994 and 2015 reporting the prevalence and/or spectrum of BRCA1 (OMIM 113705) and BRCA2 (OMIM 600185) variants. The combined sample size for these studies consisted of 4835 individuals from 13 countries in Latin America and the Caribbean, as well as in Hispanics in the United States. A total of 167 unique pathogenic variants have been reported in the existing literature. In unselected breast cancer cases, the prevalence ranged from 1.2 to 27.1%. Some countries presented a few recurrent pathogenic variants, while others were characterized by diverse, non-recurrent variants. The proportion of BRCA pathogenic variants shared between Hispanics in the United States and Latin American populations was estimated at 10.4%. Within Latin America and the Caribbean, 8.2% of the BRCA variants reported were present in more than one country. Countries with high prevalence of BRCA pathogenic variants may benefit from more aggressive testing strategies, while testing of recurrent variant panels might present a cost-effective solution for improving genetic testing in some, but not all, countries.

Evaluation of BRCA1 mutations in an unselected patient population with triple-negative breast cancer

Triple-negative breast cancer (TNBC) is characterized by aggressive behavior and poor prognosis. While >50 % of patients with inherited BRCA1 mutations have TNBC, the prevalence of BRCA1 mutations in patients with TNBC remains unclear. Deciphering the relationship between BRCA1 and TNBC is critical to understanding the etiology of TNBC, leading to improved patient counseling and treatment. All female patients with TNBC enrolled in the Clinical Breast Care Project were identified. Genomic DNA was isolated from blood and the exonic regions of the BRCA1 gene were amplified and sequenced. Sequence data was analyzed and mutations identified using Sequencher 4.10.1. Of the 190 women with TNBC, genomic DNA was available for 182. Seventy percent of patients were considered high-risk for having a BRCA1 mutation based on the National Comprehensive Cancer Network criteria. Clinically relevant mutations were detected in 16 (9 %) patients ranging in age from 26 to 69 years at diagnosis. Six of these patients were diagnosed >50 years. The C61G mutation was found in three Caucasian women diagnosed >40 years, while six African-American women had mutations, including the 943ins10 West African founder mutation. Upon conclusion, causative BRCA1 mutations were detected in 9 % of TNBC patients, including patients without significant family histories and/or diagnosed at a later age. The mutation frequency in patients <60 years was 11.2-18.3 % in those patients with significant risk factors and 4.6 % in those without, while in patients >60 years, the mutation frequency was 3.5-7.7 % in patients with risk factors, 2.3 % in those without. Thus, evaluation of additional risk factors in both patients younger and older than 60 years should improve the identification of TNBC patients benefiting from genetic testing of BRCA1.

Recurrent BRCA1 and BRCA2 mutations in breast cancer patients of African ancestry

Recurrent mutations constituted nearly three quarters of all BRCA1 mutations and almost half of all BRCA2 mutations identified in the first cohort of the Nigerian Breast Cancer Study. To further characterize breast/ovarian cancer risks associated with BRCA1/BRCA2 mutations in the African diaspora, we genotyped recurrent mutations among Nigerian, African American, and Barbadian breast cancer patients. A replication cohort of 356 Nigerian breast cancer patients was genotyped for 12 recurrent BRCA1/2 mutant alleles (Y101X, 1742insG, 4241delTG, M1775R, 4359insC, C64Y, 1623delTTAAA, Q1090X, and 943ins10 from BRCA1, and 1538delAAGA, 2630del11, and 9045delGAAA from BRCA2) by means of SNaPshot followed by direct sequencing or by direct sequencing alone. In addition, 260 African Americans and 118 Barbadians were genotyped for six of the recurrent BRCA1 mutations by SNaPshot assay. Of all the BRCA1/2 recurrent mutations we identified in the first cohort, six were identified in 11 patients in the replication study. These mutation carriers constitute 3.1 % [95 % Confidence Interval (CI) 1.6-5.5 %] of the replication cohort. By comparison, 6.9 % (95 % CI 4.7-9.7 %) of the discovery cohort carried BRCA1/2 recurrent mutations. For the subset of recurrent mutations we tested in breast cancer cases from Barbados or the United States, only two 943ins10 carriers were identified in African Americans. Nigerian breast cancer patients from Ibadan carry a broad and unique spectrum of BRCA1/2 mutations. Our data suggest that BRCA1/2 mutation testing limited to recurrent mutations is not sufficient to understand the BRCA1/2-associated breast cancer risk in African populations in the diaspora. As the cost of Sanger sequencing is considerably reduced, deploying innovative technologies such as high throughput DNA sequencing of BRCA1/2 and other cancer susceptibility genes will be essential for identifying high-risk individuals and families to reduce the burden of aggressive early onset breast cancer in low-resource settings.

Novel BRCA1 deleterious mutation (c.1949_1950delTA) in a woman of Senegalese descent with triple-negative early-onset breast cancer

Limited information exists regarding BRCA1 and BRCA2 genetic testing and genetic diversity in BRCA1 and BRCA2 in sub-Saharan African populations. We report a novel mutation that consists of a deletion of 2 bp (c.1949_1950delTA) in the exon 11 of the BRCA1 gene. This is a frameshift mutation that causes the disruption of the translational reading frame resulting in a premature stop codon downstream in the BRCA1 protein. The mutation was present in a Senegalese woman with a triple-negative breast tumor and a family history of breast cancer.

Updating and refining a study brochure for a cancer registry-based study of BRCA mutations among young African American breast cancer patients: lessons learned

The aim of the present study was to update, refine, and evaluate a study brochure to promote participation in a population-based study of BRCA mutations among AA women with a personal history of early-onset breast cancer. A multi-step approach was used to develop this brochure and included: (1) feedback from community members (through a Community Advisory Panel (CAP)) to develop and refine the study brochure, (2) pilot testing of materials with the target audience, and (3) review of pilot testing results with the CAP. Based on the feedback received at each step, the study brochure was refined. In phase 1, the major changes included emphasizing the concept of leaving a legacy and family, using the terms Black and women of color, and use of patient vignettes and photos. In phase 2, attraction and cultural acceptability were identified as two areas for improvement in the study brochure. These results demonstrate that involvement of community members and target study population in the development of a study-specific brochure can provide invaluable feedback to optimize recruitment strategies. This approach can be readily adapted to develop study recruitment materials for individuals from a variety of cultural and ethnic backgrounds.

Genetic Testing for Inherited Breast Cancer Risk in African Americans

As genetic testing for BRCA1 and BRCA2 (BRCA1/2) mutations is increasingly integrated into the clinical management of high-risk women, it will be important to understand barriers and motivations for genetic counseling among women from underserved minority groups to ensure equitable access to these services. Therefore, the purpose of this review was to synthesize literature on knowledge and attitudes about genetic counseling and testing for inherited breast cancer risk in African Americans. We also review studies that evaluated genetic testing intentions in this population. We conducted a search of the PubMed database to identify studies related to BRCA1/2 testing in African Americans that were published between 1995 and 2003. Overall, studies have evaluated ethnic differences in knowledge and attitudes about genetic testing or have compared African American and Caucasian women in terms of genetic testing intentions. These studies have shown that knowledge about breast cancer genetics and exposure to information about the availability of testing is low among African Americans, whereas expectations about the benefits of genetic testing are endorsed highly. However, much less is known about the psychological and behavioral impact of genetic testing for BRCA1/2 mutations in African Americans. Additional research is needed to understand barriers and motivations for participating in genetic testing for inherited cancer risk in African Americans. The lack of studies on psychological functioning, cancer surveillance, and preventive behaviors following testing is a significant void; however, for these studies to be conducted, greater access to genetic counseling and testing in African Americans will be needed.

Hereditary breast and ovarian cancer syndrome : the impact of race on uptake of genetic counseling and testing

Breast cancer is a significant cause of morbidity and mortality in the United States. Although breast cancer is more common among White American (WA) women, incidence rates are higher among young African American (AA) women. Approximately 5-10% of all breast cancer can be accounted for by germline mutations in the breast cancer (BRCA)1 and BRCA2 genes responsible for hereditary breast and ovarian cancer (HBOC) syndrome. Although genetic counseling (GC) and genetic testing (GT) for HBOC have become widely accepted by the WA population, cancer genetic services are underused among AA. Many investigators have evaluated a wide spectrum of BRCA1 and BRCA2 mutations in the AA and African population with the possible identification of African founder mutations. Barriers to GC and GT include lack of knowledge and/or negative attitudes regarding genetics and genetics research, and concerns regarding the potential for racial discrimination. It is important for future research to focus on ways in which to eliminate barriers to GC and GT to alleviate disparity in the use of genetic services among high-risk AA women.

BRCA1/2 in high-risk African American women with breast cancer: providing genetic testing through various recruitment strategies

BACKGROUND

Due to the disproportionate numbers of African American women affected with early onset breast cancer, we sought to investigate mutation frequency of BRCA1 and BRCA2 (BRCA1/2) in a sample of African American women, recruited through a variety of methods.

METHODS

We conducted a study investigating BRCA1/2 among 51 African American breast cancer patients with a personal or family history suggestive of hereditary predisposition to breast cancer. All individuals underwent genetic counseling and BRCA1/2 mutation analysis, through protein-truncation test on exon 11 of BRCA1 and exons 10 and 11 of BRCA2, which together account for approximately 50% of mutations observed within these genes.

RESULTS

Of the 51 women tested for BRCA1/2 mutations, 3 were identified as mutation carriers (5.9%), including 1 in BRCA1 and 2 in BRCA2. Recruitment strategies varied and included physician referrals from the Moffitt Cancer Center Breast Program (18), community-based oncologists (13), primary care physicians (3), newspaper advertisements and brochures (5), community or support group referrals (7), self/family referral through word of mouth (2), and the Florida State Cancer Registry (3).

CONCLUSIONS

Our results suggest that (1) BRCA1/2 mutations are seen in high-risk African American women with breast cancer, and (2) strategies for recruitment of African American women in studies of genetic testing for breast cancer genes have varied levels of success. Our study highlights the need for further studies in this population group.

Genetic counseling and testing for common hereditary breast cancer syndromes: a paper from the 2007 William Beaumont hospital symposium on molecular pathology

Throughout the past 15 years, the identification of several genes associated with hereditary breast cancer has fueled the growth of clinical genetic counseling and testing services. In addition, increased knowledge of the genetic and molecular pathways of the known hereditary breast cancer genes, as well as an increased understanding of the impact of testing on individuals has added to the ability to identify, manage, and provide psychosocial support for mutation carriers. This review provides an overview of the clinical features, cancer risks, causative genes, and management for hereditary breast and ovarian cancer syndrome, Cowden syndrome, and Li-Fraumeni syndrome. This article summarizes the genetic counseling process and genetic test result interpretation, including a review of the key elements involved in the provision of risk assessment and informed consent, as well as a review of the risks, benefits, and limitations of cancer susceptibility genetic testing.

Evidence for an ancient BRCA1 mutation in breast cancer patients of Yoruban ancestry

BACKGROUND

BRCA1 recurrent mutations have rarely been assessed in non-founder populations. Still, identifying such mutations could be important for designing genetic testing strategies for high-risk breast/ovarian cancer families in non-founder populations.

OBJECTIVE

To determine whether the recurrent BRCA1 Y101X mutation identified in Yoruban breast cancer patients represents a single historical mutation event, and determine the prevalence of this mutation in a hospital based cohort.

METHODS

365 breast cancer patients and 177 controls of Yoruban ancestry from Nigeria, unselected for age of onset or family history were screened for the BRCA1 Y101X mutation. The haplotypes on which the Y101X mutation occurred were characterized using microsatellite markers and single-nucleotide polymorphisms (SNPs). Phase ambiguity was resolved using allele-specific PCR.

RESULTS

The BRCA1 Y101X mutation was detected in four Yoruban patients with no documented family history of breast cancer among a cohort of 365 (1.1, 95% C.I. = 0.43-2.78%) unrelated Yoruban breast cancer patients. This study reveals the four Y101X mutations occur on a single, rare haplotype. Further characterization in a patient of European ancestry with a strong family history of breast/ovarian cancer revealed the same Y101X mutation on the same haplotype as those in the Yoruban carriers. These observations suggest the Y101X mutations identified in the Yoruban patients may have originated from a single mutation event.

CONCLUSIONS

BRCA1 Y101X is the first reported recurrent mutation occurring in patients of African ancestry for which prevalence has been determined. Identification of this mutation in a woman of European ancestry with strong family history of breast/ovarian suggests further that this mutation occurred once, probably many generations ago.

Frequency of the basal-like phenotype in African breast cancer

Basal-like breast carcinoma has been recognized as a subtype with specific prognostic implications. However, there is a lack of reports about this category of breast tumors in African women. The aim of this study was to explore the basal-like phenotype in breast cancer patients in an African population, and a registry-based series was included from the well-defined Kyadondo County in Uganda (1.7 millions). We studied a total of 65 archival paraffin blocks of invasive breast cancer using antibodies against cytokeratin 5/6 and P-cadherin, and these markers were expressed in 34% of all cases and in 52% of ER (estrogen receptor)-negative tumors. All basal-like tumors were ER negative (p<0.0005) and PR (progesterone receptor) negative (p=0.002). Basal-like breast carcinomas were of a higher histologic grade (p=0.001), had high mitotic counts (p=0.002), and marked nuclear pleomorphism (p=0.002). P-cadherin-positive tumors had a high Ki-67 proliferative rate (p=0.039). In conclusion, the basal-like phenotype is frequent in this African series of breast cancer and is strongly associated with poor prognostic factors. Our findings might be significant in relation to clinical management of these patients, including novel targeted therapy.

Breast cancer risk associated with BRCA1 and BRCA2 in diverse populations

Germline mutations in the BRCA1 or BRCA2 tumour-suppressor genes are strong predictors of breast and/or ovarian cancer development. The contribution of these mutations to breast cancer risk within any specific population is a function of both their prevalence and their penetrance. Mutation prevalence varies among ethnic groups and may be influenced by founder mutations. Penetrance can be influenced by mutation-specific phenotypes and the potential modifying effects of the patient's own genetic and environmental background. Although estimates of both mutation prevalence and mutation penetrance rates are inconsistent and occasionally controversial, understanding them is crucial for providing accurate risk information to each patient.

Breast cancer in sub-Saharan Africa: how does it relate to breast cancer in African-American women?

BACKGROUND

African-American women have had a lower incidence, yet higher mortality rate from breast cancer compared with White-American women. African-American women also have had a higher risk for early-onset, high-grade, node-positive, and hormone receptor-negative disease. Similar features have characterized hereditary breast cancer, prompting speculation that risk factors could be genetically transmitted. Further evaluation of this theory required the study of breast cancer among women from sub-Saharan Africa because of their shared ancestry with African-American women.

METHODS

Publications from 1988 to 2004 of English-language literature on breast cancer in Africa were reviewed.

RESULTS

Women from sub-Saharan Africa were found to have a low incidence of breast cancer. This was partly explained by a largely protective reproductive history, including late menarche, early menopause, high parity with prolonged breastfeeding, irregular menses, and fewer ovulatory cycles. The average age at diagnosis, however, was approximately 10 years younger than breast cancer patients of western nations, and disease stage distribution was shifted toward more advanced disease, which resulted in higher mortality rates. These features were found to be similar to data on breast cancer in African-American women. Mutations in BRCA1 and BRCA2 have been reported in African-American women, but the extent of the contribution of BRCA1 and BRCA2 to breast cancer burden in Africa was uncertain. Limited financial resources lead to suboptimal cancer data collection, as well as delayed diagnosis and treatment of many African breast cancer patients.

CONCLUSIONS

Parallels between breast cancer burdens of African-American and sub-Saharan-African women were provocative, indicating the need for further exploration of possible genetically transmitted features related to estrogen metabolism and/or breast cancer risk.

BRCA1 variants in a family study of African-American and Latina women

We sequenced the entire coding region of BRCA1 to improve our understanding of the frequency and nature of BRCA1 variants in African-American and Latina women identified from a multiethnic cohort in Los Angeles, California. The study included 109 African-American and 140 Latina sibships from families with two or more cases of breast or ovarian cancer among first-degree relatives. BRCA1 was sequenced in 278 breast or ovarian cancer cases and 229 unaffected sisters. The proportion of cases with known disease-causing mutations was low (0.72, 95% confidence interval: 0-1.7%). In total, 33 sequence variants were identified, including two protein truncation mutations, one deletion, and six silent and 24 missense variants. Two novel rare variants were identified that appeared to act as benign polymorphisms. Four rare variants may be unique to women of African descent based on existing literature, and three have been described exclusively in Latina women. The frequency of common variants was similar for cases and controls, but the frequency of common variants for African-American women significantly differed from those previously described for Caucasian women. We believe this to be the largest study of high-risk African-American and Latina women sequenced for variants in the BRCA1 gene to date.

Breast Cancer in African‐American Women

African-American women face a lower risk of being diagnosed with breast cancer as compared to Caucasian-American women, yet they paradoxically face an increased breast cancer mortality hazard. An increased incidence rate for early-onset disease has also been documented. This manuscript review summarizes the socioeconomic, environmental, genetic, and possible primary tumor biologic factors that may explain these disparities.

BRCA1 and BRCA2 Mutations in a Study of African American Breast Cancer Patients

The spectrum of mutations in BRCA1 and BRCA2 among African Americans has not been well characterized because most studies to date have been done in Caucasian families. According to Myriad Genetic Laboratories, Inc., only ∼3% of individuals undergoing BRCA1/BRCA2 testing reported African American ancestry. Data from previous studies show that among African American women a greater proportion of breast cancer cases are diagnosed at age &lt;45 years in comparison with Caucasians. Because breast cancer occurring at a young age is one of the hallmarks of high penetrance genes, the prevalence, spectrum, and effects of BRCA1/BRCA2 mutations may differ substantially between African Americans and Caucasians, and further investigation is warranted.

We conducted a hospital-based study of African American breast cancer patients with early age at diagnosis (≤45 years) or family history of breast or ovarian cancer. We identified four deleterious mutations in BRCA1 or BRCA2 among the 10 families tested, of which two were novel BRCA2 mutations, one was the west African founder mutation (BRCA1 943ins10), and one was a recurrent mutation that may be a candidate for a second African American founder mutation (BRCA1 IVS13+1G&gt;A). Our results support previous data in demonstrating that (a) the spectrum of mutations among African Americans is unique, (b) family history of breast cancer is an important predictor of hereditary cancer susceptibility among African Americans, and (c) empirical data may be useful in estimating mutation risk among African Americans.

BRCA1 testing in breast and/or ovarian cancer families from northeastern France identifies two common mutations with a founder effect

OBJECTIVE

The purpose of this study was to determine whether two mutations detected frequently in a population of breast and/or ovarian cancer families originating from the northeastern part of France could be due to a founder effect.

METHODS

83 index cases of families ascertained to have a familial breast and/or ovarian cancer history, were screened for mutations in all coding exons of the BRCA1 gene, using combined DGGE and direct sequencing. For haplotype analysis, six polymorphic markers were used for allelotyping of mutation carriers and non carriers from nine families with 3600del11 mutation and four families with G1710X mutation.

RESULTS

Of 83 index cases, 27 (32%) had 14 different BRCA1 mutations, one of which (G1710X), had not been reported in other populations. Two mutations were particularly common: 3600del11 in exon 11 accounted for 37% and the nonsense mutation G1710X in exon 18 for 15% of all mutations. We identified a common haplotype for each mutation suggesting a common founder for each recurrent mutation. No specific phenotype could be assigned to any of the common mutations.

CONCLUSIONS

These data demonstrate geographical clustering and suggest a founder effect for particular BRCA1 mutations, which identification will facilitate carrier detection in French families with breast cancer and breast and/or ovarian cancer.

Sociocultural influences on participation in genetic risk assessment and testing among African American women

The objectives of this observational study were to describe the associations between cultural beliefs and values and participation in genetic risk assessment and testing among African American women at high risk for having a BRCA1 or BRCA2 (BRCA1/2) gene alteration. Subjects were 28 high-risk women who self-referred to a genetic counseling and testing research program. Overall, 61% subjects received BRCA1/2 test results and 39% declined. Mean levels of fatalistic beliefs about cancer and future temporal orientation were higher among test acceptors relative to decliners. Sociodemographic factors were not associated with test acceptance; however, rates of test acceptance were lower among women with greater perceptions of familial interdependence (41% versus 91%, P=0.02). The results of this study suggest that cultural beliefs and values may influence genetic testing decisions among African American women.

Breast cancer genetics in African Americans

BACKGROUND

An overview of the state of genetic testing for BRCA1 and BRCA2 genes was presented at the Summit Meeting on Breast Cancer Among African American women.

METHODS

An exhaustive literature search was performed using PubMed and abstracts published from meetings of the American Association for Cancer Research, the American Society of Human Genetics, and the American Society of Clinical Oncology. The Breast Cancer Information Core was also searched for information regarding sequence variants in which the ethnicity of the individual tested was known.

RESULTS

Of the 26 distinct BRCA1 pathogenic mutations (protein-truncating, disease-associated missense, and splice variants) detected in Africans or African Americans, 15 (58%) have not been previously reported. In addition, 18 deleterious BRCA2 mutations have been identified and 10 (56%) of these are unique to the group. Only two pathogenic BRCA1 mutations (943ins10 and M1775R) have been detected in three or more unrelated families. However, seven additional BRCA1 or BRCA2 deleterious mutations have been reported in at least two unrelated families. Three of these recurrent BRCA1 mutations (943ins10, 1832del5, and 5296del4) have been characterized by haplotype studies and each likely arose from a common ancestor, including one ancestor that could be traced to the Ivory Coast in West Africa. Although only a few African-American families have been tested for BRCA1 and BRCA2 mutations, the probability of finding a mutation is invariably dependent on the age of onset and the number of breast and/or ovarian cancer cases in the family. The psychosocial implications of genetic testing for African Americans have not been well studied, so that high-risk African Americans may underestimate their risks of breast and ovarian cancer.

CONCLUSIONS

Deleterious BRCA1 and BRCA2 mutations have been identified in African-American and African families. A number of unique mutations have been described, but recurrent mutations are widely dispersed and are not readily identifiable in the few families that have been tested. Access to genetic counseling and testing in a culturally sensitive research setting must remain a high priority before genetic testing can be disseminated in the community.

Germline BRCA1-2 mutations in non-Ashkenazi families with double primary breast and ovarian cancer

OBJECTIVE

Ashkenazi women with double primary breast and ovarian cancer have a high prevalence (57%) of germline Jewish founder mutations in the BRCA1 (185delAG, 5382insC) and BRCA2 (6174delT) genes. The purpose of this study was to determine the frequency and type of BRCA1-2 mutations in non-Ashkenazi families with at least one member having double primary breast and ovarian cancer.

METHODS

Women at increased risk for cancer based upon their family history were enrolled at the University of Texas Southwestern Familial Cancer Registry between 1992 and 2000. Blood samples from patients desiring genetic testing were sent for complete DNA sequencing of the BRCA1 and BRCA2 genes. Families with a member having both breast and ovarian cancer were identified and clinical data were obtained.

RESULTS

Sixty-two (7%) of 900 enrolled families were non-Ashkenazi and had at least one member with double primary breast and ovarian cancer. Twenty-one families had members who underwent genetic testing; 41 did not. Thirteen (62%) families had a germline BRCA1 (n = 11) or BRCA2 (n = 2) mutation; only one Jewish founder mutation (185delAG) was detected. Eight (38%) families tested negative. Six (86%) of seven women undergoing genetic testing who themselves had double primary breast and ovarian cancer were BRCA1-2 mutation carriers.

CONCLUSIONS

Germline BRCA1-2 mutations are common in non-Ashkenazi families with a member having double primary breast and ovarian cancer. These mutations occurred throughout both genes, emphasizing the need for comprehensive sequencing. One family had the BRCA2 6985delCT mutation, which lies beyond the "ovarian cancer cluster" region.

Characteristics of BRCA1 mutations in a population-based case series of breast and ovarian cancer

Breast and ovarian cancers account for approximately 210000 newly diagnosed cases per year. More than half a million American women are estimated to be carriers of a breast cancer susceptibility gene. The purpose of this study was to assess the association of characteristics such as, age at diagnosis, race/ethnicity and family history of cancer with inherited BRCA1 mutations in a population-based sample of breast and ovarian cancer cases. No selection was made by race, age at diagnosis or positive family history of breast or ovarian cancer. The population under study was all breast cancer cases diagnosed in Orange County, CA, during the 1-year period beginning 1 March 1994 and all ovarian cancer cases diagnosed in Orange County during the 2-year period beginning 1 March 1994. This report focuses on the first consecutively ascertained 802 participating probands enrolled in the study, of which 9 were male breast cancer probands, 673 were female breast cancer probands and 120 were ovarian cancer probands. We observed 11 BRCA1 mutations or 1.6% (95% CI: 0.8-2.9) among the 673 female breast cancer probands and 4 BRCA1 mutations or 3.3% (95% CI: 0.8-8. 3) among the 120 ovarian cancer probands. No BRCA1 mutations were identified among the 98 non-white breast and ovarian cancer probands. The prevalence of BRCA1 mutations in non-Hispanic-white breast cancer cases below the age of 50 years was 2%. Positive family history of breast or ovarian cancers was significantly associated with BRCA1 mutation status among breast cancer probands. Similarly, positive family history of breast or ovarian cancer was significantly associated with BRCA1 mutation status among the ovarian cancer probands. In summary, we present results on the prevalence of BRCA1 mutations in a significantly larger sample of population-based breast and ovarian cancer cases than previously reported. The results indicate that, using a conservative approach to targeted genotyping of BRCA1, the frequency of mutations was consistent with those reported using similar methods of population-based case ascertainment.

Founder populations and their uses for breast cancer genetics

Numerous founder mutations have been reported in BRCA1 and BRCA2. For genetic screening of a population with a founder mutation, testing can be targeted to the mutation, allowing for a more rapid and less expensive test. In addition, more precise estimates of the prior probability of carrying a mutation and of the likelihood of a mutation carrier developing cancer should be possible. For a given founder mutation a large number of carriers are available, so that focused scientific studies of penetrance, expression, and genetic and environmental modifiers of risk can be performed. Finally, founder populations may be a powerful resource to localize additional breast cancer susceptibility loci, because of the reduction in locus heterogeneity.