Spectrum of BRCA1/2 point mutations and genomic rearrangements in high-risk breast/ovarian cancer Chilean families

The distribution of BRCA1/2 germline mutations in breast/ovarian cancer (BC/OC) families varies among different populations. In the Chilean population, there are only two reports of mutation analysis of BRCA1/2, and these included a low number of BC and/or OC patients. Moreover, the prevalence of BRCA1/2 genomic rearrangements in Chilean and in other South American populations is unknown. In this article, we present the mutation-detection data corresponding to a set of 326 high-risk families analyzed by conformation-sensitive gel electrophoresis and heteroduplex analysis. To determine the contribution of BRCA1/2 LGRs in Chilean BC patients, we analyzed 56 high-risk subjects with no pathogenic BRCA1/2 point mutations. Germline BRCA1/2 point mutations were found in 23 (7.1%) of the 326 Chilean families. Families which had at least three BC and/or OC cases showed the highest frequency of mutations (15.9%). We identified 14 point pathogenic mutations. Three recurrent mutations in BRCA1 (c.187_188delAG, c.2605_2606delTT, and c.3450_3453delCAAG) and three in BRCA2 (c.4969_4970insTG, c.5374_5377delTATG, and c.6503_6504delTT) contributed to 63.6 and 66.7% of all the deleterious mutations of each gene, which may reflect the presence of region-specific founder effects. Taken together BRCA1/2 recurrent point mutations account for 65.2% (15/23) of the BRCA1/2 (+) families. No large deletions or duplications involving BRCA1/2 were identified in a subgroup of 56 index cases negative for BRCA1/2 point mutations. Our study, which is the largest conducted to date in a South American population, provides a comprehensive analysis on the type and distribution of BRCA1/2 mutations and allelic variants.     

Relationship of BRCA1 and BRCA2 mutations with cancer burden in the family and tumor incidence

The aim of the present study is to analyze the relationship of the incidence of mutations in the two major genes BRCA1 and BRCA2 conferring risk of breast cancer (BC) and ovarian cancer (OC) with the cancer burden in families and with the presence and age of onset of BC/OC. We included 704 index patients (IP) and 668 family members of the IP who tested positive for BRCA1/BRCA2 who were studied in the Program of Genetic Counselling in Cancer of the Valencia Community (Spain). We found 129 IPs with deleterious mutations (18.3%), 59 in BRCA1 and 70 in BRCA2, detecting 396 mutations in this kindred. The incidence of mutations and their distribution between BRCA1 and BRCA2 showed a significantly uneven incidence among the family groups (P < 0.001). We found 179 tumors in the 396 mutation carriers (45%) and detected only 11 cancers among the 272 non-mutation carriers (P < 0.001). No differences in the tumor prevalence or the age of onset of cancer between the genes among the mutation carriers were found. The mutation carriers showed a 50% probability of having BC/OC at a median age of 49 years (95% CI 46–52 years) and 78% at the age of 70 years (95% CI: 71–85%). In conclusion the family burden of BC and OC is strongly associated with the incidence of BRCAs mutations and could foretell which of the two BRCAs genes is more likely to have mutations. Mutation carriers have a 50% risk of having BC/OC by the age of 50 years.     

Genetic analysis of BRCA1 and BRCA2 in breast/ovarian cancer families from Aragon (Spain): two novel truncating mutations and a large genomic deletion in BRCA1

We screened BRCA1 and BRCA2 germline mutations in 60 high-risk breast and/or ovarian cancer patients and 20 relatives from Aragon (Spain) by DHPLC (Denaturing High Performance Liquid Chromatography) and direct sequencing of the entire coding sequence and the splicing sites of both genes. We have identified 17 different pathogenic mutations: 8 in BRCA1 and 9 in BRCA2 in 60 unrelated patients and 50% of relatives were carriers. The prevalence of pathogenic mutations in this study was 33.33%. Two truncating mutations are novel: c.5024_5025delGA in exon 16 of BRCA1 and c.2929delC in exon 11 of BRCA2 (numbered after GenBank U14680 and U43746). Multiplex Ligation Dependent Probe Amplification (MLPA) was performed for large mutational scanning of both genes and a large genomic deletion in BRCA1 was found (DelEx8-13). Furthermore, five mutations are described for the first time in Spanish population: c.1191delC, c.3478_3479delTT and c.6633_6637delCTTAA (BRCA1) and c.3972_3975delTGAG and 3908_3909delTG (BRCA2). Three mutations have been reported previously once in Spain: c.3600_3610del11 (BRCA1), c.5804_5807delTTAA (BRCA2) and c.9246C>A (BRCA2). The mutation c.5374_5377delTATG has been found before only in two unrelated families from Castilla-Leon, Spain (BRCA2). Frequent mutations described in Spanish population have also been present: c.187_188delAG, c.5242C>A and c.5385insC in BRCA1 and c.3492_3493insT and c.9254_9258delATCAT in BRCA2. c.5242C>A, 3972_3975delTGAG and c.5804_5807delTTAA were the recurrent mutations found. Fifteen different unclassified variants were identified (25% families). Although specific BRCA1 and BRCA2 mutations are recurrently reported as a result of genetic founder effects we conclude that heterogeneous ethnicity increases the variety of mutations that can be found in Spanish populations.     

About 1% of the breast and ovarian Spanish families testing negative for BRCA1 and BRCA2 are carriers of RAD51D pathogenic variants

RAD51D mutations have been recently identified in breast (BC) and ovarian cancer (OC) families. Although an etiological role in OC appears to be present, the association of RAD51D mutations and BC risk is more unclear. We aimed to determine the prevalence of germline RAD51D mutations in Spanish BC/OC families negative for BRCA1/BRCA2 mutations. We analyzed 842 index patients: 491 from BC/OC families, 171 BC families, 51 OC families and 129 patients without family history but with early‐onset BC or OC or metachronous BC and OC. Mutation detection was performed with high‐resolution melting, denaturing high‐performance liquid chromatography or Sanger sequencing. Three mutations were found in four families with BC and OC cases (0.82%). Two were novel: c.1A>T (p.Met1?) and c.667+2_667+23del, leading to the exon 7 skipping and one previously described: c.674C>T (p.Arg232*). All were present in BC/OC families with only one OC. The c.667+2_667+23del cosegregated in the family with one early‐onset BC and two bilateral BC cases. We also identified the c.629C>T (p.Ala210Val) variant, which was predicted in silico to be potentially pathogenic. About 1% of the BC and OC Spanish families negative for BRCA1/BRCA2 are carriers of RAD51D mutations. The presence of several BC mutation carriers, albeit in the context of familial OC, suggests an increased risk for BC, which should be taken into account in the follow‐up and early detection measures. RAD51D testing should be considered in clinical setting for families with BC and OC, irrespective of the number of OC cases in the family.     

The prevalence of BRCA mutations among familial breast cancer patients in Korea: results of the Korean Hereditary Breast Cancer study

The primary aim of this study was to estimate the prevalence of BRCA1/2 mutations among familial breast cancer (BC) patients in Korea. We analyzed 775 familial BC patients who were enrolled in the Korean Hereditary Breast Cancer (KOHBRA) study and treated at 36 institutions between May 2007 and May 2010. Patients with familial BC were defined as BC patients with family histories of BC or ovarian cancer (OC) in any relatives. All probands received genetic counseling and BRCA genetic testing was performed after obtaining informed consent. The mean age of BC diagnosis was 43.6 years. The numbers of probands with family histories of BC only and OC only were 682 and 93, respectively. The overall prevalence of the BRCA mutation among familial BC patients was 21.7 % (BRCA1 9.3 % and BRCA2 12.4 %). Subgroup analyses observed prevalences of the BRCA mutation as follows: 19.6 % among patients with BC family history only (BRCA1 7.6 % and BRCA2 12.0 %) and 36.6 % among patients with OC family history only (BRCA1 21.5 % and BRCA2 15.1 %). Most of the subgroups satisfied the 10 % probability criteria to undergo BRCA testing. However, the prevalence of the BRCA mutations among subgroups that had 2 BC patients in a family with both age at diagnosis of more than 50 years old did not reach the 10 % criteria (4.1 %). Korean familial BC patients are good candidates for BRCA testing even when they have family histories of single breast cancers. However, proband age at diagnosis should be carefully considered when selecting patients for testing.     

Comprehensive splicing functional analysis of DNA variants of the BRCA2 gene by hybrid minigenes

Introduction

The underlying pathogenic mechanism of a large fraction of DNA variants of disease-causing genes is the disruption of the splicing process. We aimed to investigate the effect on splicing of the BRCA2 variants c.8488-1G > A (exon 20) and c.9026_9030del (exon 23), as well as 41 BRCA2 variants reported in the Breast Cancer Information Core (BIC) mutation database.

Methods

DNA variants were analyzed with the splicing prediction programs NNSPLICE and Human Splicing Finder. Functional analyses of candidate variants were performed by lymphocyte RT-PCR and/or hybrid minigene assays. Forty-one BIC variants of exons 19, 20, 23 and 24 were bioinformatically selected and generated by PCR-mutagenesis of the wild type minigenes.

Results

Lymphocyte RT-PCR of c.8488-1G > A showed intron 19 retention and a 12-nucleotide deletion in exon 20, whereas c.9026_9030del did not show any splicing anomaly. Minigene analysis of c.8488-1G > A displayed the aforementioned aberrant isoforms but also exon 20 skipping. We further evaluated the splicing outcomes of 41 variants of four BRCA2 exons by minigene analysis. Eighteen variants presented splicing aberrations. Most variants (78.9%) disrupted the natural splice sites, whereas four altered putative enhancers/silencers and had a weak effect. Fluorescent RT-PCR of minigenes accurately detected 14 RNA isoforms generated by cryptic site usage, exon skipping and intron retention events. Fourteen variants showed total splicing disruptions and were predicted to truncate or eliminate essential domains of BRCA2.

Conclusions

A relevant proportion of BRCA2 variants are correlated with splicing disruptions, indicating that RNA analysis is a valuable tool to assess the pathogenicity of a particular DNA change. The minigene system is a straightforward and robust approach to detect variants with an impact on splicing and contributes to a better knowledge of this gene expression step.     

CASP8 D302H polymorphism delays the age of onset of breast cancer in BRCA1 and BRCA2 carriers

The polymorphic genetic differences among individuals may modify the high risk for breast cancer (BC) and/or ovarian cancer (OC) susceptibility conferred by BRCA1 and BRCA2 mutations. In the present study we investigate the relevance of RAD51 ?135C > G, TP53 R72P, NQO1*2 and CASP8 D302H polymorphisms as potential modifiers of BC and/or OC susceptibility conferred by these mutations. The study group encompasses 390 BRCA1/BRCA2 mutation carriers (182 affected with BC and/or OC and 208 unaffected) of 131 unrelated families studied in the Program of Genetic Counselling on Cancer of Valencia Community. The polymorphisms were detected in genomic DNA by ASRA method or real time PCR using fluorescently labeled probes. We found similar incidence of RAD51 ?135C > G, TP53 R72P and NQO1*2 polymorphisms among affected and unaffected individuals considering BRCA1/BRCA2 mutations together and separately. However, the CASP8 D302H polymorphism was strongly associated with the absence of BC [OR = 3.41 (95% CI 1.33–8.78, P = 0.01)]. In fact, in the females with CASP8 D302H polymorphism the BC appeared at a median age of 58 in opposition to the 47 years observed for the wild type subjects (P = 0.03). Furthermore, the CASP8 D302H positive females showed a 50% probability of being free of BC by the age of 78 versus the 2% of the CASP8 negative ones. Our results support that the presence of the CASP8 D302H polymorphism diminishes the high risk of BC conferred by BRCA1 and BRCA2 mutations, making possible that some of the carriers could escape from suffering BC along their life span.     

Screening for common mutations in BRCA1 and BRCA2 genes: interest in genetic testing of Tunisian families with breast and/or ovarian cancer

BackgroundIn the Tunisian population, as yet a limited number of BRCA1/2 germline mutations have been reported in hereditary breast and/or ovarian cancer. These mutations are located in a few exons of BRCA1/2. The aim of the present study was to search for these mutations in 66 unrelated patients with hereditary breast and/or ovarian cancer in order to assess the interest in such a targeted approach for genetic testing in Tunisia.Materials and MethodsBlood specimens from the 66 Tunisian patients, with family history of breast and/or ovarian cancer, were collected at the Salah Azaiz Cancer Institute of Tunis. The exons 5, 20 and part of exon 11 of BRCA1 as well as part of exons 10 and 11 of BRCA2 were analyzed by Sanger sequencing.Results12 patients had deleterious mutations in the BRCA1 or BRCA2 genes (18%), including a novel frame-shift mutation of BRCA1 (c.3751dup; 3780insT). Four distinct BRCA1 mutations were detected eight patients: c.5266dup (5382insC) and c.211dup (330insA) each in three patients, c.3751dup (3870insT) and c.4041_4042del (4160delAG) each in one patient. The four remaining cases all carried the same BRCA2 mutation, c.1310_1313del (1538delAAGA). Besides these deleterious mutations, eight polymorphisms and unclassified variants were detected, one of them being never reported (BRCA1c.3030T>G, p.Pro1010Pro).ConclusionIn this study, we show that targeting relevant exons in BRCA1 and BRCA2 genes allows detection of a substantial percentage of mutations in the Tunisian population. Therefore such an approach may be of interest in genetic testing of high-risk breast and ovarian cancer families in Tunisia.     

BRCA1 mutation analysis in 83 Spanish breast and breast/ovarian cancer families.

A group of 83 Spanish BC/OC families were analysed for BRCA1 germ-line mutations. Analysis of the entire coding sequence was carried out by SSCP and PTT. We identified 5 frameshift mutations: 185delAG (2 times), 189insTGTC, 1241delAC, and 5537delA and 3 missense mutations in BRCA1: 330A > G, 1240C > T, and 5263G > A. The 185delAG mutation was identified in 2 families. One of them was the only Gypsy family participating in our study. All carriers shared the known founder haplotype, although they did not have any Jewish ancestry. Three frameshift mutations were found among the 14 families with 3 or more BC cases and 1 or more OC, which results in a higher percentage (21.4%) of BRCA1 mutations in this group of high risk families. Two missense mutations were found in families with 2 or 3 BC and no OC, indicating a low proportion (4.8%) of mutations in these families. There was no association between bilateral BC and a mutation carrier status. The frequency of BRCA1 involvement is lower than that of any other country hitherto reviewed. Our results highlight the influence of geographical and ethnic origin of the population studied.     

BRCA2 germ-line mutations in Spanish male breast cancer patients

Background:Mutations in the BRCA2 gene account for the majorityof the families with male and female breast cancer cases, and a number ofBRCA2 mutations have been reported in males with breast cancer. The aim ofthis study was to characterise BRCA2 germ-line mutations in Spanish malebreast cancer patients. Patients and methods:We screened DNA from 11 affected men and 6women with breast cancer (BC) who had an affected male relative (father orbrother). Exons 2–9 and 12–27 were screened by SSCP, and exons 10and 11 were screened by PTT. PCR products with a variant band were sequenced. Results:Three BRCA2 frameshift mutations were identified(17.6%): the 3374delA in codon 1049 (exon 11), 6857delAA in codon 2010(exon 11), and 9254delATCAT in codon 3009 (exon 23). These mutations werepresent in patients with affected first-degree relatives (3 of 9, 33%).The proportion of male patients with a family history of BC in at least onefirst-degree relative was 53%. Conclusions:There is an association between BRCA2 mutations andmale breast cancer, especially in those with a family history of BC. The highprevalence of BRCA2 mutations among males should be considered when estimatingrisk for female relatives. All new male cases of BC should be regarded asbeing possibly inherited and should be fully investigated.     

Founder mutations account for the majority of BRCA1-attributable hereditary breast/ovarian cancer cases in a population from Tuscany, Central Italy

Background Germline mutations in the BRCA1 and BRCA2 tumour-suppressor genes predispose to early-onset breast and ovarian cancer. Although both genes display a highly heterogeneous mutation spectrum, a number of alterations recur in some populations. Only a limited number of founder mutations have been identified in the Italian population so far. Objective To investigate the spectrum of BRCA1/BRCA2 mutations in a set of families originary from the Central–Eastern part of Tuscany and to ascertain the presence of founder effects. We also wanted to approximate the age of the most frequent BRCA1 founder mutation. Results Overall, four distinct BRCA1 mutations accounted for a large fraction (72.7%) of BRCA1-attributable hereditary breast/ovarian cancer in families originary from this area. We identified common haplotypes for two newly recognised recurrent BRCA1 mutations, c.3228_3229delAG and c.3285delA. The c.3228_3229delAG mutation was estimated to have originated about 129 generations ago. Interestingly, male breast cancer cases were present in 3 out of 11 families with the c.3228_3229delAG mutation. Conclusions The observation that a high proportion of families with BRCA1 alterations from Central–Eastern Tuscany harbours a limited number of founder mutations can have significant impact on clinical management of at risk subjects from this area. In addition, the identification of a large set of families carrying an identical mutation that predisposes to breast and ovarian cancer provides unique opportunities to study the effect of other genetic and environmental factors on penetrance and disease phenotype.     

Frequency of <Emphasis Type="Italic">BRCA1</Emphasis> and <Emphasis Type="Italic">BRCA2</Emphasis> causative founder variants in ovarian cancer patients in South-East Poland

Background

Causative variants in BRCA1 and BRCA2 are well-established risk factors for breast and ovarian cancer. In Poland, the causative founder variants in the BRCA1 are responsible for a significant proportion of ovarian cancer cases, however, regional differences in the frequencies of various mutations may exist. The spectrum and frequency of BRCA1/2 mutations between ovarian cancer patients have not yet been studied in the region of South-East Poland.

Methods

We examined 158 consecutive unselected cases of ovarian cancer patients from the region of Podkarpacie. We studied 13 Polish causative founder variants in BRCA1 (c.5266dupC, c.4035delA, c.5251C?>?T, c.181 T?>?G, c.676delT, c.68_69delAG, c.3700_3704delGTAAA, c.1687C?>?T, c.3756_3759delGTCT) and in BRCA2 (c.658_659delGT, c.7910_7914delCCTTT, c.3847_3848delGT, c.5946delT).

Results

A BRCA1 causative founder variants were detected in 10 of the 158 (6.3%) ovarian cancer cases. BRCA2 causative founder variants were not observed. The c.5266dupC mutation was detected in 6 patients, c.181 T?>?G mutation in 3 patients and the c.676delT mutation in 1 patient. The median age of diagnosis of the 10 hereditary ovarian cancers was 55.5 years of age.

Conclusions

The frequency of 13 causative founder variants in Podkarpacie was lower than in other regions of Poland. Testing of three BRCA1 mutations (c.5266dupC, c.181 T?>?G, c.676delT) should be considered a sensitive test panel.

     

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.     

Prevalence of BRCA1 and BRCA2 Germline Mutations in Patients of African Descent with Early-Onset and Familial Colombian Breast Cancer

BackgroundPathogenic germline mutations in the BRCA1 and BRCA2 (BRCA1/2) genes contribute to hereditary breast/ovarian cancer (OC) in White/mestizo Colombian women. As there is virtually no genetic data on breast cancer (BC) in Colombians of African descent, we conducted a comprehensive BRCA1/2 mutational analysis of 60 Afro-Colombian families affected by breast/OC.Materials and MethodsMutation screening of the complete BRCA1/2 genes for small-scale mutations and large genomic alterations was performed in these families using next-generation sequencing and multiplex ligation-dependent probe amplification analysis.ResultsFour pathogenic germline mutations, including one novel mutation, were identified, comprising 3 in BRCA1 and one in BRCA2. The prevalence of BRCA1/2 mutations, including one BRCA1 founder mutation (c.5123C>A) previously identified in this sample set, was 3.9% (2/51) in female BC-affected families and 33.3% (3/9) in those affected by both breast and OC. Haplotype analysis of 2 BRCA2_c.2701delC carriers (one Afro-Colombian and one previously identified White/mestizo Colombian patient with BC) suggested that the mutation arose in a common ancestor.ConclusionOur data showed that 2/5 (40%) mutations (including the one previously identified in this sample set) are shared by White/mestizo Colombian and Afro-Colombian populations. This suggests that these 2 populations are closely related. Nevertheless, variations in the BRCA1/2 mutational spectrum among Afro-Colombian subgroups from different regions of the country were observed, suggesting that specific genetic risk assessment strategies need to be developed.     

<Emphasis Type="Italic">BRCA1</Emphasis> and <Emphasis Type="Italic">BRCA2</Emphasis> germline variants in breast cancer patients from the Republic of Macedonia

Purpose

We aimed to establish the spectrum of BRCA1/2 mutations among the breast cancer (BC) patients from the Republic of Macedonia.

Methods

We used targeted next-generation sequencing (NGS), Sanger DNA sequencing, and multiplex ligation probe amplification analysis (MLPA) to search for point mutations and deletions/duplications involving BRCA1 and BRCA2-coding regions.

Results

We have analyzed a total of 313 BC patients, enriched for family history of cancer, early age of onset and bilateral and/or triple negative (TN) BC. A total of 26 pathogenic mutations were observed in 49 unrelated BC patients (49/313, 15.7%). BRCA2 mutations (27/49, 55.1%) were more common than BRCA1 mutations (22/49, 44.9%). We identified five novel point mutations, one in BRCA1 (c.4352_4356delA) and four in BRCA2 (c.151G>T, c.4707_4708delCA, c.7811_7814delTGTG, and c.9304_9305delG), as well as two novel deletions involving parts of the BRCA1 gene (c.81??_593+?del and c.5470??_5530+?del). The most common mutations were c.181T>G, c.5266dupC, and c.3700_3704del5 in BRCA1 and c.7879A>T, c.8317_8330del14 and c.5722_5723delCT in BRCA2 gene. Thus far, BRCA2 c.7879A>T and c.8317_8330del14 mutations have been described in several isolated cases; however, our study is the first one showing that they have a founder effect among Macedonian population. Nine recurrent mutations account for 65.3% of all of the detected mutations allowing for implementation of a fast first-step BRCA1/2 mutational screening strategy in our country.

Conclusion

This study provides a comprehensive view of known and novel BRCA1/2 mutations in BC patients from the Republic of Macedonia and contributes to the global spectrum of BRCA1/2 mutations in breast cancer.

     

Limited significance of family history for presence of BRCA1 gene mutation in Polish breast and ovarian cancer cases

It is estimated that about 5–10% of ovarian and 2–5% of all breast cancer patients are carriers of a germline BRCA1 or BRCA2 gene mutation. Most families with detected BRCA1 or BRCA2 gene mutation are qualified for molecular testing on the basis of family history of breast or ovarian cancers. The purpose of our study was to establish the frequency of positive family history of cancer in a series of Polish consecutive breast and ovarian cancer patients in two groups, with and without the BRCA1 gene mutations. We analysed the prevalence of four of the most common BRCA1 mutations: 5382insC (c.5266dupC), 300T>G (p.181T>G), 185delAG (c.68_69delAG) and 3819del5 (c.3700_3704del5). The patient group consisted of 1,845 consecutive female breast and 363 ovarian cancer cases. 19 out of 37 (51%) of BRCA1-positive ovarian cancer patients and 21 out of 55 (39%) BRCA1-positive breast cancer had negative family history of breast and/or ovarian cancer among first- and second-degree relatives. In ovarian cancer patients, negative family history was more frequent in those with 300T>G BRCA1 gene mutation than in 5382insC carriers. This finding indicates the necessity of searching for 300T>G mutation in families with a single diagnosis of ovarian cancer in family. The high frequency of mutations detected in breast cancer patients lacking obvious family history shows that breast cancer patients should be qualified for genetic testing on the basis of wide clinical and pathological criteria.     

<Emphasis Type="Italic">BRCA1/BRCA2</Emphasis> founder mutations and cancer risks: impact in the western Danish population

Mutations in the BRCA1 and BRCA2 genes significantly contribute to hereditary breast cancer and ovarian cancer, but the phenotypic effect from different mutations is insufficiently recognized. We used a western Danish clinic-based cohort of 299 BRCA families to study the female cancer risk in mutation carriers and their untested first-degree relatives. Founder mutations were characterized and the risk of cancer was assessed in relation to the specific mutations. In BRCA1, the cumulative cancer risk at age 70 was 35 % for breast cancer and 29 % for ovarian cancer. In BRCA2, the cumulative risk was 44 % for breast cancer and 15 % for ovarian cancer. We identified 47 distinct BRCA1 mutations and 48 distinct mutations in BRCA2. Among these, 8 founder mutations [BRCA1 c.81-?_4986+?del, c.3319G>T (p.Glu1107*), c.3874delT and c.5213G>A (p.Gly1738Glu) and BRCA2 c.6373delA, c.7008?1G>A, c.7617+1G>A and c.8474delC] were found to account for 23 % of the BRCA1 mutations and for 32 % of the BRCA2 mutations. The BRCA1 mutation c.3319G>T was, compared to other BRCA1 mutations, associated with a higher risk for ovarian cancer. In conclusion, founder mutations in BRCA1 and BRCA2 contribute to up to one-third of the families in western Denmark and among these the BRCA1 c.3319G>T mutation is potentially linked to an increased risk of ovarian cancer.     

Absence of loss of heterozygosity of BRCA1 in a renal tumor from a BRCA1 germline mutation carrier

BRCA1 functions as a tumor suppressor gene and germline and somatic mutations in this gene have been shown to be associated with many types of cancer. We report the first tumor study of renal cell carcinoma in a carrier of the deleterious BRCA1 mutation-c.68_69delAG.     

Family history predictors of BRCA1/BRCA2 mutation status among Tunisian breast/ovarian cancer families

Background

With the increasing request for BRCA1/BRCA2 mutation tests, several risk models have been developed to predict the presence of mutation in these genes; in this study, we have developed an efficient BRCA genetic testing strategy.

Method

As first step, to identify predictor variables associated with BRCA status, we have undertaken a cumulative mutation analysis including data from three Tunisian studies. Then, we have developed a logistic regression model for predicting the likelihood of harboring a BRCA mutation. Using receiver operating characteristic curves (ROC), an effective evaluation was performed. A total of 92 Tunisian families were included. Overall, 27 women were positive for BRCA1/BRCA2 deleterious mutations.

Results

Tow recurrent mutations (c.211dupA and c.5266dupC) explained 76 % of BRCA1-related families and three recurrent mutations (c.1310_1313del, c.1542_1547delAAGA and c.7887_7888insA) explained 90 % of BRCA2-related families. Early age at diagnosis of breast cancer, ovarian cancer, bilateral breast cancer were associated with BRCA1, whereas male breast cancer and four or more breast cancer cases in the family were associated with BRCA2. The area under the receiver operating characteristic curve of the risk score was 0.802 (95 % confidence interval = 0.0699–0. 905).

Conclusion

Logistic regression reported particular profiles related to BRCA germline mutation carriers in our population, as well as an efficient prediction model that may be a useful tool for increasing the cost-effectiveness of genetic testing strategy.

     

Prevalence of the BRCA1 founder mutation c.5266dupin Brazilian individuals at-risk for the hereditary breast and ovarian cancer syndrome

About 5-10% of breast and ovarian carcinomas are hereditary and most of these result from germline mutations in the BRCA1 and BRCA2 genes. In women of Ashkenazi Jewish ascendance, up to 30% of breast and ovarian carcinomas may be attributable to mutations in these genes, where 3 founder mutations, c.68_69del (185delAG) and c.5266dup (5382insC) in BRCA1 and c.5946del (6174delT) in BRCA2, are commonly encountered. It has been suggested by some authors that screening for founder mutations should be undertaken in all Brazilian women with breast cancer. Thus, the goal of this study was to determine the prevalence of three founder mutations, commonly identified in Ashkenazi individuals in a sample of non-Ashkenazi cancer-affected Brazilian women with clearly defined risk factors for hereditary breast and ovarian cancer (HBOC) syndrome. Among 137 unrelated Brazilian women from HBOC families, the BRCA1c.5266dup mutation was identified in seven individuals (5%). This prevalence is similar to that encountered in non-Ashkenazi HBOC families in other populations. However, among patients with bilateral breast cancer, the frequency of c.5266dup was significantly higher when compared to patients with unilateral breast tumors (12.1% vs 1.2%, p = 0.023). The BRCA1 c.68_69del and BRCA2 c.5946del mutations did not occur in this sample. We conclude that screening non-Ashkenazi breast cancer-affected women from the ethnically heterogeneous Brazilian populations for the BRCA1 c.68_69del and BRCA2 c.5946del is not justified, and that screening for BRCA1c.5266dup should be considered in high risk patients, given its prevalence as a single mutation. In high-risk patients, a negative screening result should always be followed by comprehensive BRCA gene testing. The finding of a significantly higher frequency of BRCA1 c.5266dup in women with bilateral breast cancer, as well as existence of other as yet unidentified founder mutations in this population, should be further assessed in a larger well characterized high-risk cohort.