Germline BRCA1 mutation analysis in Indian breast/ovarian cancer families

Most of the predisposition to hereditary breast and ovarian cancer has been attributed to inherited defects in two tumor suppressor genes BRCA1 and BRCA2. To explore the contribution of BRCA1 mutations to hereditary breast cancer among Indian women, we examined the coding sequence of the BRCA1 gene in 14 breast cancer patients 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. Three mutations (21%) in the BRCA1 gene were identified. Two of them are novel mutations of which one is a missense mutation in exon 7 near the RING finger domain, while the other is a one base pair deletion in exon 11 which results in protein truncation. The third mutation, 185 delAG, has been previously described in Ashkenazi Jewish families. To our knowledge this is the first report of a study of germline BRCA1 mutation analysis in familial breast cancer in India. Our data from 14 different families suggests a lower prevalence but definite involvement of germline mutations in the BRCA1 gene among Indian women with breast cancer and a family history of breast cancer.     

Germline mutation analysis of BRCA1 and BRCA2 genes in Yugoslav breast/ovarian cancer families.

The frequency of germline BRCA1 and BRCA2 mutations was tested in Yugoslav breast and breast/ovarian cancer families using combined heteroduplex/single-strand conformation polymorphism analysis for the entire coding region of both genes. Three different recurrent BRCA1 mutations (one 185delAG, one 3447del4 and two 5382insC) were identified in 4 of 12 families (33%), whereas no definite disease-causing alterations of BRCA2 was detected. Genotype analysis revealed a possible common founder effect for each 185delAG and 5382insC. The relatively high frequency of germline BRCA1 mutations determined in this panel of families confirms the important role of BRCA1 in disease predisposition in the Yugoslav population, while the lack of population specific founder and/or unique mutations show the need of further analysis of samples from this yet unexamined region of Europe.     

Germline mutation in DNA‐repair genes is associated with poor survival in BRCA1/2‐negative breast cancer patients

BRCA1/2 genes are the most frequently germline mutated DNA‐repair genes, and the survival of BRCA1/2 carriers has been extensively explored in breast cancer. However, the prevalence of germline mutations in non‐BRCA1/2 DNA‐repair genes and the survival of carriers are largely unknown in a large cohort of unselected breast cancer patients. Germline mutations in 16 DNA‐repair genes were determined using a multigene panel in 7657 BRCA1/2‐negative breast cancer patients who were unselected for family history of cancer or age at diagnosis. Among the 7657 BRCA1/2‐negative breast cancer patients, 257 (3.4%) carried at least 1 pathogenic germline mutation in the 16 DNA‐repair genes. The prevalence of DNA‐repair gene mutations was significantly higher in familial breast cancers (5.2%, P = 0.002) and early‐onset breast cancers (diagnosed at and before the age of 40) (4.5%, P = 0.003) than that of sporadic breast cancers (2.9%) (diagnosed above age of 40), respectively. The DNA‐repair gene mutation carriers were significantly more likely to have a larger tumor (P = 0.04) and axillary lymph node metastasis (P = 0.03). Moreover, DNA‐repair gene mutation was an independent unfavorable factor for recurrence‐free survival (adjusted hazard ratio [HR] = 1.38, 95% CI: 1.00‐1.91, P = 0.05) and disease‐specific survival (adjusted HR=1.63, 95% CI: 1.04‐2.57, P = 0.03) in this cohort. Overall, 3.4% of BRCA1/2‐negative breast cancer patients carried germline mutations in the 16 DNA‐repair genes, and the DNA‐repair gene mutation carriers exhibited an aggressive phenotype and had poor survival compared with noncarriers.     

家族性和早发性乳腺癌BRCA1基因突变分析

目的 分析中国黑龙江省家族性和早发性乳腺癌中BRCA1基因的突变情况。方法 以黑龙江地区的92例家族性和早发性乳腺癌(发病年龄≤35岁)为研究对象。由静脉血提取基因组DNA,对BRCA1基因的全部编码序列(除外1,4号外显子)进行扩增。由聚丙烯酰胺凝胶电泳分析(SSCP)进行突变的初筛,之后进行DNA直接测序证实。结果 在92例乳腺癌患者中发现有5种致病性突变,其中3种为新发现的突变,发现的已报道的2种突变均为无义突变。结论 在中国黑龙江人群中,BRCA1基因的突变对于遗传性乳腺癌的发生可能具有较重要意义;新发现的3个突变位点可能是中国人群中的特有突变;黑龙江地区BRCA1在家族性乳腺癌中突变率明显低于国内外报道,但其中的移码突变3712insG分别在3个患者中检出,提示有可能成为该地区的基础突变。     

Analysis of cancer risk and BRCA1 and BRCA2 mutation prevalence in the kConFab familial breast cancer resource

Introduction

The Kathleen Cuningham Foundation Consortium for Research into Familial Breast Cancer (kConFab) is a multidisciplinary, collaborative framework for the investigation of familial breast cancer. Based in Australia, the primary aim of kConFab is to facilitate high-quality research by amassing a large and comprehensive resource of epidemiological and clinical data with biospecimens from individuals at high risk of breast and/or ovarian cancer, and from their close relatives.

Methods

Epidemiological, family history and lifestyle data, as well as biospecimens, are collected from multiple-case breast cancer families ascertained through family cancer clinics in Australia and New Zealand. We used the Tyrer-Cuzick algorithms to assess the prospective risk of breast cancer in women in the kConFab cohort who were unaffected with breast cancer at the time of enrolment in the study.

Results

Of kConFab's first 822 families, 518 families had multiple cases of female breast cancer alone, 239 had cases of female breast and ovarian cancer, 37 had cases of female and male breast cancer, and 14 had both ovarian cancer as well as male and female breast cancer. Data are currently held for 11,422 people and germline DNAs for 7,389. Among the 812 families with at least one germline sample collected, the mean number of germline DNA samples collected per family is nine. Of the 747 families that have undergone some form of mutation screening, 229 (31%) carry a pathogenic or splice-site mutation in BRCA1 or BRCA2. Germline DNAs and data are stored from 773 proven carriers of BRCA1 or BRCA1 mutations. kConFab's fresh tissue bank includes 253 specimens of breast or ovarian tissue – both normal and malignant – including 126 from carriers of BRCA1 or BRCA2 mutations.

Conclusion

These kConFab resources are available to researchers anywhere in the world, who may apply to kConFab for biospecimens and data for use in ethically approved, peer-reviewed projects. A high calculated risk from the Tyrer-Cuzick algorithms correlated closely with the subsequent occurrence of breast cancer in BRCA1 and BRCA2 mutation positive families, but this was less evident in families in which no pathogenic BRCA1 or BRCA2 mutation has been detected.     

BRCA1 promoter methylation in peripheral blood DNA of mutation negative familial breast cancer patients with a BRCA1 tumour phenotype

Introduction

Individuals with germline mutations in the BRCA1 gene have an elevated risk of developing breast cancer, and often display characteristic clinicopathological features. We hypothesised that inactivation of BRCA1 by promoter methylation could occur as a germline or an early somatic event that predisposes to breast cancer with the phenotype normally associated with BRCA1 germline mutation.

Methods

We examined seven cases from breast-ovarian cancer families with tumours that showed BRCA1-like pathology but did not have detectable BRCA1 or BRCA2 germline mutations present. Methylation levels were tested by several quantitative techniques including MethyLight, methylation-sensitive high resolution melting (MS-HRM) and a newly developed digital MS-HRM assay.

Results

In one patient, methylation of 10% of the BRCA1 alleles was detected in the peripheral blood DNA, consistent with 20% of cells having one methylated allele. Buccal mucosa DNA from this individual displayed approximately 5% BRCA1 methylation. In two other patients, methylation of BRCA1 was detected in the peripheral blood at significantly lower but still readily detectable levels (approximately 1%). Tumour DNAs from these three patients were heavily methylated at BRCA1. The other patients had no detectable BRCA1 methylation in their peripheral blood. One of seven age-matched controls showed extremely low levels of methylation in their peripheral blood (approximately 0.1%).

Conclusion

These results demonstrate that in some cases of breast cancer, low-level promoter methylation of BRCA1 occurs in normal tissues of the body and is associated with the development of BRCA1-like breast cancer.     

Complete mutation screening and haplotype characterization of BRCA1 gene in Tunisian patients with familial breast cancer

Breast cancer, the most commonly diagnosed cancer in women, is the second leading cause of cancer death in women worldwide. To investigate the contribution of BRCA1 gene mutations to familial breast cancer in Tunisia, 32 unrelated patients who had at least one first degree relative affected with breast and/or ovarian cancer were analysed. BRCA1 mutation analysis was performed by DNA sequencing of all BRCA1 exons. We identified four different BRCA1 frameshift mutations: c.4041delAG, c.2551delG and c.5266dupC already been described and one novel mutation, c.211dupA, observed in two unrelated families. C.5266dupC has previously been found among Jewish Ashkenazi and Eastern European populations. Our study describes it in Arabic/Berber population. Five out of thirty two familial cases had deleterious BRCA1 mutations. Fifteen additional cases carried unclassified variants (UV) or single nucleotide polymorphisms (SNPs). Our study is the first molecular investigation on the role of BRCA1 in hereditary breast cancer in North Tunisia.     

家族性乳腺癌家系成员乳腺癌易感基因突变的研究

目的研究河北省地区家族性乳腺癌家系中的患者及健康一级亲属乳腺癌易感基因1（BRCAl）和乳腺癌易感基因2（BRCA2）突变位点及携带情况。方法研究对象为2002年6月至2008年5月河北医科大学第四医院接诊的乳腺癌患者及其亲属,分别来自12个独立的汉族家族性乳腺癌家系,该家系中有2个及2个以上一级或二级亲属乳腺癌患病史,研究病例包括13例患者及46例健康一级亲属,共59例样本。由外周血提取基因组DNA,采用聚合酶链反应一单链构象多态性分析（PCR—SSCP）和基因测序技术对国内外报告中常见的4个BRCAl／BRCA2突变热点区域（BRCAl：外显子2、11、20;BRCA2外显子11）进行检测。结果发现1个BRCAl突变位点（4193insA）和1个BRCA2突变位点（5329insT）,全部为移码突变;发现4个变异位点（BRCAl：4165T〉A、287G〉C,BRCA2：6251G〉T、5416C〉A）,4193insA、5329insT、287G〉C携带者的家系中均有3例乳腺癌患者。结论BRCAl（4193insA）、BRCA2（5329insT）以及BRCAl：4165T〉A、287G〉C和BRCA2：6251G〉T、5416C〉A可能是河北省家族性乳腺癌相关性突变位点,其携带者家系中乳腺癌发病率明显升高,建议对其一级亲属密切随访或尽早进行手术或药物干预。     

家族性乳腺癌患者及家系成员乳腺癌易感基因携带情况调查

目的 乳腺癌易感基因1(breast cancer susceptibility gene 1,BRCA1)和BRCA2基因已经证实与家族性乳腺癌密切相关.本研究旨在分析中国汉族家族性乳腺癌患者及家系成员BRCA1和BRCA2突变特征及携带情况.方法 收集2013 12-02-2015-06-08军事医学科学院附属医院确诊的中国汉族家族性乳腺癌患者55例及家系成员48名,共计103例样本.柚取外周静脉血提取DNA,应用聚合酶链反应(polymerase chain reaction,PCR) DNA直接测序方法检测BRCA1和BRCA2基因全编码外显子序列.结果 55例家族性乳腺癌患者中发现5个BRCA基因致病性突变位点,1个突变位点乳腺癌信息库中见报道(BRCA1:4730insG),4个为新发现突变位点(BRCA1:1937insC,4538insAG;BRCA2:1382delA,2820delA).家族性乳腺癌患者BRCA1/2突变率为9.09％(BRCA1,5.45％;BRCA2,3.64％),其中三阴性乳腺癌患者突变率为22.22％(x2 =1.99,P=0.20),早发性乳腺癌患者(≤35岁)突变率为20.00％,x2=0.79,P=0.39.48例家系成员检测到3个新发现突变位点(BRCA1:1370insA,3459insA;BRCA2:6502insT),总突变率为6.25％.结论 中国汉族家族性乳腺癌患者BRCA基因突变率显著低于国外,应重点关注有家族史的三阴性乳腺癌患者和早发性乳腺癌患者;家系成员中发现BRCA基因致病性突变,家系成员突变率和发病风险有待进一步研究,应引起重视.     

Prevalance of BRCA1 and BRCA2 mutations in familial breast cancer patients in Lebanon

Breast cancer is the most prevalent malignancy in women in Western countries, currently accounting for one third of all female cancers. Familial aggregation is thought to account for 5–10 % of all BC cases, and germline mutations in BRCA1 and BRCA2 account for less of the half of these inherited cases. In Lebanon, breast cancer represents the principal death-causing malignancy among women, with 50 % of the cases diagnosed before the age of 50 years.In order to study BRCA1/2 mutation spectra in the Lebanese population, 72 unrelated patients with a reported family history of breast and/or ovarian cancers or with an early onset breast cancer were tested. Fluorescent direct sequencing of the entire coding region and intronic sequences flanking each exon was performed.A total of 38 BRCA1 and 40 BRCA2 sequence variants were found. Seventeen of them were novel. Seven confirmed deleterious mutations were identified in 9 subjects providing a frequency of mutations of 12.5 %. Fifteen variants were considered of unknown clinical significance according to BIC and UMD-BRCA1/BRCA2 databases.In conclusion, this study represents the first evaluation of the deleterious and unclassified genetic variants in the BRCA1/2 genes found in a Lebanese population with a relatively high risk of breast cancer.     

Germline BRCA1 mutations in Iranian women with breast cancer

BRCA1 is known as a familial early onset breast cancer gene located in the long arm of chromosome 17. Alterations in this gene have been reported in different populations, some of which are population-specific mutations showing a founder effect. In this study, which is the first report on the genetic testing of Iranian women, exon-2 of the BRCA1 gene was sequenced in 80 Iranian breast cancer patients and none of the patients showed the 185del AG mutation or any changes in the sequences of this exon. Among this population, 22 patients having one or more of any kind of tumor in their first-degree relatives were selected and their entire BRCA1 gene coding region was sequenced by direct PCR-sequencing. A novel point mutation in exon-16, with unknown significance, was observed among the breast cancer patients and control subjects. This A/G mutation caused the substitution of Glutamine 1612 with Glycine, with an allele frequency of 38.6 and 52.8% in patients and controls, respectively. In addition, a point mutation in exon-15 and eight other polymorphic alterations were detected which have been reported previously. Three of these polymorphic sites were placed in the intronic part of the gene. To understand the significance of the contribution of the BRCA1 gene in the breast cancer among Iranian, further investigations are needed.     

219例中国汉族遗传性乳腺癌患者BRCA1和BRCA2突变的研究

背景与目的:BRCA1和BRCA2是通过家系连锁分析确定的与乳腺癌、卵巢癌家族高度相关的两个基因,目前国内关于中国汉族遗传性乳腺癌BRCA1和BRCA2突变研究的样本量都不大,而且大部分研究仅检测了BRCA1或部分BRCA2,并不能真正反映汉族遗传性乳腺癌的遗传特征.本研究旨在建立中国汉族人群遗传性乳腺癌患者中BRCA1和BRCA2的突变谱,并确定高危突变的家族特征.方法:来自3个中心的219个独立的家系纳入本研究,每个家系中的先证者进行BRCA1和BRCA2全外显子以及外显子内含子拼接区的突变检测.结果:219例患者检测到23例致病性突变,7例位于BRCA1,16例位于BRCA2.BRCA1和BRCA2的突变率与家系特征有关,家族性乳腺癌/卵巢癌患者BRCA1和BRCA2的突变率分别14.3% (1/7)和28.6% (2/7);早发性遗传性乳腺癌患者BRCA1的突变率为22.2%(2/9);而在非早发性遗传性乳腺癌患者BRCA2的突变率明显高于BRCA1(7.8% ,6/77 vs 0%, 0/77, P=0.028).结论:BRCA1和BRCA2突变率与家族特征有关,在非早发性遗传性乳腺癌家族中BRCA2突变值得关注.     

遗传性乳腺癌BRCA1/2甲基化研究及生存分析

目的探讨BRCA1/2启动子甲基化状态和临床病理特征对遗传性乳腺癌患者生存时间的影响。方法2005-01-01-2011-01-01新疆医科大学附属肿瘤医院乳腺外科收治的病理确诊的乳腺癌患者74例。检测乳腺癌组织中BRCA1/2基因启动子甲基化状态;收集相关临床病理特征(年龄、遗传背景、肿瘤大小、腋窝淋巴结转移情况、分子亚型、肿瘤细胞分级和临床分期),应用Cox回归模型分析影响生存时间的因素。结果 74例乳腺癌患者BRCA基因未突变者中,共发现24例BRCA1/2基因启动子甲基化,甲基化率为32.43%(24/74)。其中BRCA1基因启动子甲基化率为25.68%(19/74),BRCA2基因启动子甲基化率为6.76%(5/74),差异有统计学意义,χ2=9.747,P=0.002。单因素分析结果显示,肿瘤大小(χ2=15.927,P<0.001)、腋窝淋巴结转移(χ2=20.490,P<0.001)、临床分期(χ2=39.589,P<0.001)和分子分型(χ2=15.093,P=0.001)方面的差异有统计学意义。多因素分析结果显示,临床分期和肿瘤分子分型是影响生存时间的危险因素,OR值分别为1.436和2.181。结论 BRCA1/2启动子甲基化不是影响遗传性乳腺癌生存时间的主要因素;分子亚型为HER-2过表达型和临床分期晚的遗传性乳腺癌预后差。     

Germline BRCA1 mutations and a basal epithelial phenotype in breast cancer

A basal epithelial phenotype is found in not more than 15% of all invasive breast cancers. Microarray studies have shown that this phenotype is associated with breast cancers that express neither estrogen receptor (ER) nor erbB-2 (HER2/neu) (i.e., ER/erbB-2-negative tumors). The ER/erbB-2- negative phenotype is also found in breast cancers occurring in BRCA1 mutation carriers (i.e., BRCA1-related breast cancers). We tested the hypothesis that BRCA1-related breast cancers are more likely than non-BRCA1/ 2-related breast cancer to express a basal epithelial phenotype. Among 292 breast cancer specimens previously analyzed for ER, erbB-2, p53, and germline mutations in BRCA1 and BRCA2, we identified 76 that did not overexpress ER or erbB-2. Of the 72 specimens with sufficient material for testing, 40 expressed stratified epithelial cytokeratin 5 and/or 6 (5/6). In univariate analysis, the expression of cytokeratin 5/6 was statistically significantly associated with BRCA1-related breast cancers (odds ratio = 9.0, 95% confidence interval = 1.9 to 43; P =.002, two-sided Fisher's exact test). Thus, germline BRCA1 mutations appear to be associated with a distinctive breast cancer phenotype.     

Large genomic rearrangement of BRCA1 and BRCA2 genes in familial breast cancer patients in Korea

We screened large genomic rearrangements of the BRCA1 and BRCA2 genes in Korean, familial breast cancer patients. Multiplex ligation-dependent probe amplification assay was used to identify BRCA1 and BRCA2 genomic rearrangements in 226 Korean familial breast cancer patients with risk factors for BRCA1 and BRCA2 mutations, who previously tested negative for point mutations in the two genes. We identified only one large deletion (c.4186-1593_4676-1465del) in BRCA1. No large rearrangements were found in BRCA2. Our result indicates that large genomic rearrangement in the BRCA1 and BRCA2 genes does not seem like a major determinant of breast cancer susceptibility in the Korean population. A large-scale study needs to validate our result in Korea.     

Contralateral breast cancer in BRCA1 and BRCA2 mutation carriers.

PURPOSE: To estimate the risk of contralateral breast cancer in BRCA1 and BRCA2 carriers after diagnosis and to determine which factors are predictive of the risk of a second primary breast cancer. PATIENTS AND METHODS: Patients included 491 women with stage I or stage II breast cancer, for whom a BRCA1 or BRCA2 mutation had been identified in the family. Patients were followed from the initial diagnosis of cancer until contralateral mastectomy, contralateral breast cancer, death, or last follow-up. RESULTS: The actuarial risk of contralateral breast cancer was 29.5% at 10 years. Factors that were predictive of a reduced risk were the presence of a BRCA2 mutation (v BRCA1 mutation; hazard ratio [HR], 0.73; 95% CI, 0.47 to 1.15); age 50 years or older at first diagnosis (v 相似文献   

Germline TP53 mutations in BRCA1 and BRCA2 mutation-negative French Canadian breast cancer families

About 40% of French Canadian breast and/or ovarian cancer families harbor germline BRCA1 or BRCA1 mutations where common mutations account for about 84% of all mutations identified in cancer families. Within a series of BRCA1 and BRCA2 mutation-negative families, a germline TP53 13398 G>A (Arg213Gln) mutation was identified, which was selected for mutation analysis in this gene because of a family history consistent with Li–Fraumeni syndrome (LFS). Given the founder effects in this population, the 13398 G>A mutation was screened in series of 52 BRCA1 and BRCA2 mutation-negative cancer families, and a mutation-positive family was identified. However, pedigree inspection and expansion of mutation-positive families with the same mutation revealed that they were closely related to each other. To further characterize the contribution of TP53 in cancer families, mutation analysis was performed in the remaining BRCA1 and BRCA2 mutation-negative cancer families. Thirty sequence variants were identified, the majority of which occur in intronic sequences and are not predicted to affect the functionality of TP53. However, the 14538 G>A (Arg290His) mutation was identified in a family which did not exhibit features consistent with LFS or Li–Fraumeni-like (LFL) syndrome. Neither of the TP53 mutations was detected in 381 French Canadian women with breast cancer diagnosed before 50 years of age not selected for family history of cancer. In all, germline TP53 mutations were identified in two of 52 (3.8%) cancer families, suggesting that TP53 is not a major contributor to BRCA1 and BRCA2 mutation-negative breast and/or ovarian cancer families of French Canadian descent.