BRCA1 germline mutations and tumor characteristics in Chinese women with familial or early-onset breast cancer

P21 Ser31Arg and FGFR2 rs2981582 Polymorphisms as Risk Factors for Early Onset of Breast Cancer in Yogyakarta, Indonesia

Objectives:

Breast cancer tend to be more progressive with poorer prognosis in younger patients than those at an older age. Single Nucleotide Polymorphisms (SNPs) of P53 Pro72Arg, MDM2 SNP309, P21 Ser31Arg, ER SNP594, HER2 Ile655Val, and FGFR2 rs2981582 have drawn attention as genetic factors associated with cancer risk. However, there were contradictory results involving different races and their association is still unknown in Indonesian populations. This study was performed to examine the proportion of these six genes polymorphisms and their associations with age of onset of breast cancer patients in Yogyakarta, Indonesia.

Methods:

Biorepository DNA from 199 patients registered at Dr. Sardjito Hospital Yogyakarta from 2006-2013 were tested for polymorphisms using the PCR-RFLP method. Samples were taken from two age groups; early-onset (<40 years) and late-onset of breast cancer (>55 years). Chi-square tests with odds ratio were used for data analysis.

Results:

The mean age of the early-onset group was 36±4.2 years, while the late-onset group was 62±6.9 years. AA genotype and A allele of P21 and TT genotypes and T allele of FGFR2 were significantly more frequent and were associated with an increased risk of early-onset of breast cancer (95%CI: 2.54 and 1.59; 2.63 and 1.64, respectively).

Conclusions:

Our study indicates that the A allele of P21 and the allele T of FGFR2 may be associated with an increased risk of early-onset of breast cancer in Yogyakarta, Indonesia. Further analysis is needed to confirm the findings.

Germline mutations in 40 cancer susceptibility genes among Chinese patients with high hereditary risk breast cancer

Multigene panel testing of breast cancer predisposition genes have been extensively conducted in Europe and America, which is relatively rare in Asia however. In this study, we assessed the frequency of germline mutations in 40 cancer predisposition genes, including BRCA1 and BRCA2, among a large cohort of Chinese patients with high hereditary risk of BC. From 2015 to 2016, consecutive BC patients from 26 centers of China with high hereditary risk were recruited (n = 937). Clinical information was collected and next-generation sequencing (NGS) was performed using blood samples of participants to identify germline mutations. In total, we acquired 223 patients with putative germline mutations, including 159 in BRCA1/2, 61 in 15 other BC susceptibility genes and 3 in both BRCA1/2 and non-BRCA1/2 gene. Major mutant non-BRCA1/2 genes were TP53 (n = 18), PALB2 (n = 11), CHEK2 (n = 6), ATM (n = 6) and BARD1 (n = 5). No factors predicted pathologic mutations in non-BRCA1/2 genes when treated as a whole. TP53 mutations were associated with HER-2 positive BC and younger age at diagnosis; and CHEK2 and PALB2 mutations were enriched in patients with luminal BC. Among high hereditary risk Chinese BC patients, 23.8% contained germline mutations, including 6.8% in non-BRCA1/2 genes. TP53 and PALB2 had a relatively high mutation rate (1.9 and 1.2%). Although no factors predicted for detrimental mutations in non-BRCA1/2 genes, some clinical features were associated with mutations of several particular genes.

Identification of a novel breast cancer-causing mutation in the BRCA1 gene by targeted next generation sequencing: A case report

Hereditary breast cancer is an autosomal dominant syndrome caused by germ-line mutations in the human breast cancer genes, BRCA1 and BRCA2. Mutations in either BRCA1 or BRCA2 are the major causes of familial and early-onset breast cancer. The present study investigated a 33-year-old Chinese female patient with breast cancer using targeted next generation sequencing. A novel heterozygous deletion-insertion was also identified in the BRCA1 gene, c.311_312delinsAGGTTTGCA, which causes the formation of a truncated BRCA1 protein of 109 amino acids instead of a wild-type BRCA1 protein of 1,863 amino acids. These results could potentially expand the mutational spectra of BRCA1-associated breast cancer. In addition, these findings may be valuable for the mutation-based screening and genetic diagnosis of breast cancer.

Prevalence and Spectrum of BRCA1/2 Germline Mutations in Women with Breast Cancer in China Based on Next-Generation Sequencing

Background

BRCA1 and BRCA2 (BRCA1/2) play important roles in the development of breast cancer, but information regarding BRCA1/2 mutations in Chinese females remains limited. The aim of this study was to investigate the prevalence and spectrum of BRCA1/2 mutations in China.

Material/Methods

In total, 595 breast cancer patients in China were screened with an amplicon-based panel for the detection of BRCA1/2 mutations in coding regions using next-generation sequencing (NGS) with a Personal Genome Machine. Every pathogenic mutation detected was confirmed by Sanger sequencing. The disease-causing potential of variants of uncertain significance (VUS) was predicted using PolyPhen-2, SIFT, PhyloP, and Grantham.

Results

The prevalence of BRCA1/2 mutations was 8.07% in the Chinese population. Forty-two pathogenic mutations were identified in 48 cases (17 BRCA1 cases and 31 BRCA2 cases), including 19 novel mutations. Nine VUS were predicted to be deleterious by PolyPhen-2 and SIFT and subsequently predicted by PhyloP and Grantham for the evolutionary conservation.

Conclusions

These results suggest that NGS is useful as a rapid, high-throughput, and cost-effective screening tool for the analysis of BRCA1/2 mutations. Based on this panel, we found that BRCA1/2 germline mutations in China exhibit distinct characteristics compared to those in Western populations.

BRCA1 mutation spectrum, functions, and therapeutic strategies: The story so far

BRCA1 gene mutations account for about 25-28% of hereditary Breast Cancer as BRCA1 is included in the category of high penetrance genes. Except for few commonmutations, there is a heterogenous spectrum of BRCA1 mutations in various ethnic groups. 185AGdel and 5382ins Care the most common BRCA1 alterations (founder mutations) which have been identified in most of the population. This review has been compiled with an aim to consolidate the information on genetic variants reported in BRCA1 found in various ethnic groups, their functional implications if known; involvement of BRCA1 in various cellular pathways/processes and potential BRCA1 targeted therapies. The pathological variations of BRCA1 vary among different ethical groups. A systematic search in PubMed and Google scholar for the literature on BRCA1 gene was carried out to figure out structure and function of BRCA1 gene. BRCA1 is a large protein having 1863 amino acids with multiple functional domains and interacts with multiple proteins to carry out various crucial cellular processes. BRCA1 plays a major role in maintaining genome integrity, transcription regulation, chromatin remodeling, cell cycle checkpoint control, DNA damage repair, chromosomal segregation, and apoptosis. Studies investigating the phenotypic response of mutant BRCA1 protein and comparing it to wildtype BRCA1 protein are clinically important as they are involved in homologous recombination and other repair mechanisms. These studies may help in developing more targetted therapies, detecting novel interacting partners, identification of new signaling pathways that BRCA1 is a part of or downstream target genes that BRCA1 affects.

Characterization of mutations in BRCA1/2 and the relationship with clinic-pathological features of breast cancer in a hereditarily high-risk sample of chinese population

The database of BRCA1/2 mutations in Chinese population remains incomplete at present. Therefore, the present study aimed to report specific harmful BRCA1/2 mutations in the Chinese population and discuss the clinicopathological features in mutation carriers. BRCA1/2 germline mutation tests for 71 patients with breast cancer from a hereditarily high-risk Chinese population were performed using next-generation sequencing for identification of deleterious mutations. Furthermore, the clinicopathological features between BRCA1/2 mutation carriers and non-carriers were compared. A total of 13/71 (18.3%) patients carried a BRCA1 or BRCA2 mutation (7 BRCA1 and 6 BRCA2). The incidence of BRCA1/2 mutation in patients with bilateral breast cancer and patients with family history were 25, and 32.2%, respectively. Eleven pathogenic or likely pathogenic mutations were identified in 13 patients, among the mutation sites 7 were never reported before in Asian populations. The age at diagnosis of BRCA1/2 mutation carriers was older compared with non-mutation carriers (44.73 vs. 35.39 years; P=0.001) in this cohort. BRCA1/2 deleterious mutation carriers had a significantly lower chance of human epidermal growth factor receptor-2 (Her-2) positive status (P=0.010), higher tumor grade at diagnosis (P=0.009), higher probability to have a family history (P=0.016) and older age at diagnosis. Estrogen receptor (ER) and progesterone receptor (PR) status were significantly different between BRCA1, and BRCA2 mutation carriers (P=0.007). The current interpretation of BRCA1/2 status can only explain a small part of hereditary high-risk breast cancer. However, BRCA1/2 gene testing should still be recommended for women with a family history of breast cancer, as well as patients with breast cancer with specific pathologic types, which may be useful to make appropriate clinical decisions for treatment and prevention.

BRCA1 germline mutations dominate familial breast cancer patients in Henan China

Background

Gene mutations of BRCA1 gene play a role in breast cancer. These mutations exist racial differences and can be inherited. The aim of the research is to study the relativity of BRCA1 gene germline mutations with familial breast cancer patients in Henan, China.

Methods

Comprehensive BRCA1 germline mutation analyses were performed through denaturing high-performance liquid chromatography (DHPLC) in a cohort of 59 breast cancer patients and 122 healthy donors with family history of breast cancer. The mutations detected by DHPLC were further validated by Sanger sequencing.

Results

About 52.54% (31/59) of familiar breast cancer patients showed BRCA1 germline mutations, which is higher than other previous reports with Chinese patients. However, the mutation rate was only 5.74% (7/122) in healthy donors with family history of breast cancer, and also all these mutations were in BRCA1 of all these mutations detected in both patients and healthy donors, mutation A3780G in BRCA1 gene was reported for the first time. The mutation hotspots were A3113G and A3780G in BRCA1 at least in this cohort of patients in Henan, China.

Conclusions

BRCA1 germline mutations are related most closely to familial breast cancer patients in Henan China.

Characterization of a novel germline BRCA1 splice variant, c.5332+4delA

PURPOSE

Germline mutations in BRCA1 and BRCA2 confer a significant increase in risk for cancer, and determining pathogenicity of a BRCA variant can guide the clinical management of the disease. About 1/3 of BRCA1 variants reported in the public databases have uncertain clinical significance due to lack of conclusive evidence. This study aims to characterize a novel BRCA1 deletion affecting the + 4 splice donor site identified in an individual with early-onset breast cancer.

METHODS

The effect of BRCA1 c.5332+4delA variant on RNA splicing was evaluated by amplifying regions of BRCA1 from cDNA derived from the patient. The proportion of abnormal transcript in the total transcripts was quantified. Loss of heterozygosity (LOH) in tumor tissue was investigated using Sanger sequencing and fragment analysis.

RESULTS

BRCA1 c.5332+4delA caused skipping of exon 21 in patient-derived samples. Semi-quantitative analysis indicated that this aberrant RT-PCR product accounts for about 40% of the total transcript levels. Loss of heterozygosity (LOH) was observed in patient's tumor tissue.

CONCLUSIONS

Our results indicate that the BRCA1 c.5332+4delA variant contributes to cancer predisposition through disruption of normal mRNA splicing. We classify this variant as likely pathogenic.

Prevalence and spectrum of BRCA germline variants in mainland Chinese familial breast and ovarian cancer patients

Germline mutations in BRCA1 and BRCA2 are the most penetrating genetic predispositions for breast and ovarian cancer, and their presence is largely ethnic-specific. Comprehensive information about the prevalence and spectrum of BRCA mutations has been collected in European and North American populations. However, similar information is lacking in other populations, including the mainland Chinese population despite its large size of 1.4 billion accounting for one fifth of the world's population. Herein, we performed an extensive literature analysis to collect BRCA variants identified from mainland Chinese familial breast and ovarian cancer patients. We observed 137 distinct BRCA1 variants in 409 of 3,844 and 80 distinct BRCA2 variants in 157 of 3,024 mainland Chinese patients, with an estimated prevalence of 10.6% for BRCA1 and 5.2% for BRCA2. Of these variants, only 40.3% in BRCA1 and 42.5% in BRCA2 are listed in current Breast Cancer Information Core database. We observed higher frequent variation in BRCA1 exons 11A, 11C, 11D, and 24 and BRCA2 exon 10 in Chinese patients than in the patients of other populations. The most common pathogenic variant in BRCA1 wasc.981_982delAT in exon 11A, and in BRCA2 c.3195_3198delTAAT in exon 11B and c.5576_5579delTTAA in exon 11E; the most common novel variant in BRCA1 was c.919A>G in exon 10A, and in BRCA2 c.7142delC in exon 14. None of the variants overlap with the founder mutations in other populations. Our analysis indicates that the prevalence of BRCA variation in mainland Chinese familial breast and ovarian cancer patients is at a level similar to but the spectrum is substantially different from the ones of other populations.

High prevalence and predominance of BRCA1 germline mutations in Pakistani triple-negative breast cancer patients

BACKGROUND

Women harboring BRCA1/2 germline mutations have high lifetime risk of developing breast/ovarian cancer. The recommendation to pursue BRCA1/2 testing is based on patient's family history of breast/ovarian cancer, age of disease-onset and/or pathologic parameters of breast tumors. Here, we investigated if diagnosis of triple-negative breast cancer (TNBC) independently increases risk of carrying a BRCA1/2 mutation in Pakistan.

METHODS

Five hundred and twenty-three breast cancer patients including 237 diagnosed ≤ 30 years of age and 286 with a family history of breast/ovarian cancer were screened for BRCA1/2 small-range mutations and large genomic rearrangements. Immunohistochemical analyses were performed at one center. Univariate and multiple logistic regression models were used to investigate possible differences in prevalence of BRCA1/2 mutations according to patient and tumor characteristics.

RESULTS

Thirty-seven percent of patients presented with TNBC. The prevalence of BRCA1 mutations was higher in patients with TNBC than non-TNBC (37 % vs. 10 %, P < 0.0001). 1 % of TNBC patients were observed to have BRCA2 mutations. Subgroup analyses revealed a larger proportion of BRCA1 mutations in TNBC than non-TNBC among patients 1) diagnosed at early-age with no family history of breast/ovarian cancer (14 % vs. 5 %, P = 0.03), 2) diagnosed at early-age irrespective of family history (28 % vs. 11 %, P = 0.0003), 3) had a family history of breast cancer (49 % vs. 12 %, P < 0.0001), and 4) those with family history of breast and ovarian cancer (81 % vs. 28 %, P = 0.0005). TNBC patients harboring BRCA1 mutations were diagnosed at a later age than non-carriers (median age at diagnosis: 30 years (range 22-53) vs. 28 years (range 18-67), P = 0.002). The association between TNBC status and presence of BRCA1 mutations was independent of the simultaneous consideration of family phenotype, tumor histology and grade in a multiple logistic regression model (Ratio of the probability of carrying BRCA1/2 mutations for TNBC vs. non-TNBC 4.23; 95 % CI 2.50-7.14; P < 0.0001).

CONCLUSION

Genetic BRCA1 testing should be considered for Pakistani women diagnosed with TNBC.

Clinical and pathological features of BRCA1/2 tumors in a sample of high-risk Moroccan breast cancer patients

Background

BRCA1 and BRCA2 genes explain a large part of hereditary breast cancer. Several studies have shown that BRCA1 and BRCA2 tumors exhibit some specific morphological and immunohistochemical characteristics. The aim of our study is to compare the clinicopathological characteristics between Moroccan breast cancers associated or not with BRCA1 and BRCA2 mutations. Previously, we had identified 11 BRCA carriers in a series of 40 selected breast cancer patients at increased risk for carrying a mutation in the BRCA1 and BRCA2 genes. The clinical and pathological features of patients carrying BRCA1 or BRCA2 mutation (n = 11) were evaluated and compared to those of non-mutated patients (n = 29).

Results

In comparison with non carriers, women with BRCA1/2 mutation present younger mean age at diagnosis (37.90 vs. 44.48 years, p = 0.05), younger mean age of 1st menarche (13.08 vs. 14.24 years, p = 0.05) and shorter duration of breastfeeding (8.71 vs. 19.35 months, p = 0.05). Moreover, 63.6 and 62.5 % of BRCA1/2 carriers present SBR grade III and triple negative tumors respectively (p = 0.02).

Conclusions

In this first Moroccan study comparing clinical and pathological characteristics of women carrying or not BRCA1/2 mutation, patients with BRCA mutation tend to develop early breast cancer with high-grade and triple negative tumors. However, further large scale research including more data is needed to better characterize BRCA1/2 cases and to evaluate the survival rate associated with these mutations in our population tumors. Moreover, it would be more interesting to study women with BRCA1 and BRCA2 mutations separately in order to determine if they exhibit distinct characteristics.

Comprehensive spectrum of BRCA1 and BRCA2 deleterious mutations in breast cancer in Asian countries

Approximately 5%-10% of breast cancers are due to genetic predisposition caused by germline mutations; the most commonly tested genes are BRCA1 and BRCA2 mutations. Some mutations are unique to one family and others are recurrent; the spectrum of BRCA1/BRCA2 mutations varies depending on the geographical origins, populations or ethnic groups. In this review, we compiled data from 11 participating Asian countries (Bangladesh, Mainland China, Hong Kong SAR, Indonesia, Japan, Korea, Malaysia, Philippines, Singapore, Thailand and Vietnam), and from ethnic Asians residing in Canada and the USA. We have additionally conducted a literature review to include other Asian countries mainly in Central and Western Asia. We present the current pathogenic mutation spectrum of BRCA1/BRCA2 genes in patients with breast cancer in various Asian populations. Understanding BRCA1/BRCA2 mutations in Asians will help provide better risk assessment and clinical management of breast cancer.

The expression of CXCL13 and its relation to unfavorable clinical characteristics in young breast cancer

Background

Young breast cancer occupies a higher and higher proportion of breast cancer, especially in Asia, and is associated with a more unfavorable prognosis compared with the disease arising in older women. However, the poor prognosis of young breast cancer cannot be fully explained by the clinical and molecular factors.

Methods

This study investigated 1125 Chinese breast cancer patients diagnosed from 2009 to 2013. A data mining of gene expression profiles was performed for the young and older breast cancer patients, identifying significantly differentially expressed genes. Quantitative RT-PCR, Western blotting and immunohistochemistry assay were carried out for the clinical sample validations.

Results

The investigation firstly displayed that young patients (≤45 years) accounted for 47.6 % (535/1125) of breast cancer, and clinically associated with some unfavorable factors related to poor prognosis, such as invasive pathological type, high tumor grade, lymph node positive, ER negative and triple-negative subtype. Subsequently, 553 significantly differentially expressed genes were identified by the data mining. Of them, a set of genes related to immune function were observed to be up-regulated in young patients with breast cancer. Impressively, the CXCL13 (C-X-C motif chemokine 13) expression level showed the most significant difference (FC = 2.64, P = 8.2 × 10⁻⁴). Furthermore, the validations with clinical samples and correlation analysis demonstrated that CXCL13 was indeed highly expressed in young breast cancer and closely associated with some prognostic factors including lymph node positive and ER negative.

Conclusion

This is the first to indicate the clinical relevance of CXCL13 to young breast cancer and represents a potential therapeutic target for young breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0521-1) contains supplementary material, which is available to authorized users.

Androgen receptor, EGFR, and BRCA1 as biomarkers in triple-negative breast cancer: a meta-analysis

OBJECTIVE

More and more evidences demonstrate that androgen receptor (AR), epidermal growth factor receptor (EGFR), and breast cancer susceptibility gene 1 (BRCA1) have unique clinical implications for targeted therapy or prognosis in triple-negative breast cancer (TNBC). Therefore, we conducted a meta-analysis to summarize the possible associations.

METHODS

We retrieved published articles about AR, EGFR, and BRCA1 in TNBC from PubMed and EMBASE. The analysis was performed with Rev-Man 5.2 software.

RESULTS

A total of 38 articles were eligible for the meta-analysis. Our study showed that the expression level of EGFR (OR = 6.88, P < 0.00001) and the prevalence of BRCA1 mutation (RR = 5.26, P < 0.00001) were higher in TNBC than non-TNBC. In contrast, the expression level of AR was lower in TNBC than non-TNBC (OR = 0.07, P < 0.00001). In the subgroup related to EGFR expression, the level of EGFR expression was significantly increased in Asians (OR = 9.60) compared with Caucasians (OR = 5.53) for TNBC patients. Additionally, the prevalence of BRCA1 mutation in Asians (RR = 5.43, P < 0.00001) was higher than that in Caucasians (RR = 5.16, P < 0.00001).

CONCLUSIONS

The distinct expression of AR and EGFR and the prevalence of BRCA1 mutation indicated that AR, EGFR, and BRCA1 might be unique biomarkers for targeted therapy and prognosis in TNBC.

Distribution of BRCA1 and BRCA2 Mutations in Asian Patients with Breast Cancer

Breast cancer is the most prevalent cancer in Asian females, and the incidence of breast cancer has been increasing in Asia. Because Asian patients develop breast cancer at a younger age than their Caucasian counterparts, the contributions of BRCA1 and BRCA2 (BRCA1/2) mutations in Asians are expected to be different than in Caucasians. The prevalence of BRCA1/2 mutations in the Asian population varies among countries and studies. Most Asian studies have reported more frequent mutations in BRCA2 than in BRCA1, with the exception of studies from India and Pakistan. In addition, the contribution of large genomic rearrangements of BRCA1/2 genes is relatively small in Asian populations in comparison to other ethnic populations. Various statistical models for the prediction of BRCA1/2 mutations have underestimated the risk of having these genetic mutations in Asians, especially in predicting BRCA2 gene mutation. Until recently, BRCA1/2 mutation analyses in Asia were mostly conducted by independent single institutions with different patient selection criteria and using various genotyping methods. However, a couple of Asian groups have initiated nationwide studies collecting BRCA1/2 mutational data. These national collaborative studies will help a comprehensive understanding of the prevalence of BRCA1/2 mutations in the Asian population.

Methylation of BRCA1 promoter region is associated with unfavorable prognosis in women with early-stage breast cancer

BRCA1-associated breast cancers are associated with particular features such as early onset, poor histological differentiation, and hormone receptor negativity. Previous studies conducted in Taiwanese population showed that the mutation of BRCA1 gene does not play a significant role in the occurrence of breast cancer. The present study explored methylation of BRCA1 promoter and its relationship to clinical features and outcome in Taiwanese breast cancer patients. Tumor specimens from a cohort of 139 early-stage breast cancer patients were obtained during surgery before adjuvant treatment for DNA extraction. Methylation of BRCA1 promoter region was determined by methylation-specific PCR and the results were related to clinical features and outcome of patients using statistical analysis. Methylation of the BRCA1 promoter was detected in 78 (56%) of the 139 tumors. Chi-square analysis indicated that BRCA1 promoter methylation correlated significantly with triple-negative (ER-/PR-/HER2-) status of breast cancer patients (p = 0.041). The Kaplan-Meier method showed that BRCA1 promoter methylation was significantly associated with poor overall survival (p = 0.026) and disease-free survival (p = 0.001). Multivariate analysis which incorporated variables of patients' age, tumor size, grade, and lymph node metastasis revealed that BRCA1 promoter methylation was associated with overall survival (p = 0.27; hazard ratio, 16.38) and disease-free survival (p = 0.003; hazard ratio, 12.19). Our findings underscore the clinical relevance of the methylation of BRCA1 promoter in Taiwanese patients with early-stage breast cancer.

Hereditary breast cancer in the Han Chinese population

Breast cancer is the most common malignancy among women and has a strong genetic background. So far, 13 breast cancer susceptibility genes of high or moderate penetrance have been identified. This review summarizes findings on these genes in Han Chinese. BRCA1 and BRCA2 are the 2 most important susceptibility genes. They have a relatively low mutation rate, and the most frequent sites of mutation are in exon 11. Frameshift mutations are the main type of mutation. Founder mutations may also exist, and BRCA-associated breast cancer has specific clinicopathologic characteristics. TP53 and PALB2 are relatively rare susceptibility genes. The relationship between the other 9 genes and breast cancer has not been fully elucidated. At present, the mutation spectrum for these susceptibility genes is not well understood in the Chinese population, and there are few reports on prognosis and clinical intervention in high-risk populations. Therefore, the true value of genetic counseling for breast cancer has yet to be realized. This article reviews studies of hereditary breast cancer in the Han Chinese population, highlights potential inadequacies, and provides a foundation for genetic counseling for breast cancer in China.

A comprehensive focus on global spectrum of BRCA1 and BRCA2 mutations in breast cancer

Breast cancer (BC) is the most common cancer of women all over the world. BRCA1 and BRCA2 gene mutations comprise the most important genetic susceptibility of BC. Except for few common mutations, the spectrum of BRCA1 and BRCA2 mutations is heterogeneous in diverse populations. 185AGdel and 5382insC are the most important BRCA1 and BRCA2 alterations which have been encountered in most of the populations. After those Ashkenazi founder mutations, 300T>G also demonstrated sparse frequency in African American and European populations. This review affords quick access to the most frequent alterations among various populations which could be helpful in BRCA screening programs.

BRCA1 germ-line mutations and tumor characteristics in eastern Chinese women with familial breast cancer

Although several studies detected the BRCA1 germ-line mutations in Chinese women with familial breast cancer, most of them did not employ conventional full gene sequencing, especially in eastern China. In addition, the clinicopathological features of BRCA1-associated breast cancer in Chinese women were not well investigated. In this study, we screened the complete coding regions and exon-intron boundaries of BRCA1 by polymerase chain reaction (PCR)-sequencing assay. Immunohistochemistry analyses were performed on tumor samples to detect the expression of estrogen receptor (ER), progesterone receptor (PR), P53, and human epidermal growth factor receptor-2 (HER-2). Breast cancer patients having one or more affected relatives referred from the Zhejiang Cancer Hospital, eastern China during 2008-2011 were selected for the study. A total of 62 familial breast cancer patients received the BRCA1 germ-line mutation screening. Five deleterious mutations were detected in this cohort. The mutation rate was 11.3% (7/62). We found two novel mutations (3414delC and 5,280 C > T) and two recurrent mutations (5,273 G > A and 5589del8). BRCA1 mutation tumors tended to be negative for ER, PR, and HER-2, and exhibited high histological grade compared with tumors without BRCA1 mutations. Our study suggests that recurrent mutations may exist in eastern Chinese women with familial breast cancer and PCR-sequencing assay is a useful tool to screen these mutations. It also suggests that BRCA1-associated breast cancers in Chinese women exhibit an aggressive phenotype.

Identification of BRCA1/2 founder mutations in Southern Chinese breast cancer patients using gene sequencing and high resolution DNA melting analysis

BACKGROUND

Ethnic variations in breast cancer epidemiology and genetics have necessitated investigation of the spectra of BRCA1 and BRCA2 mutations in different populations. Knowledge of BRCA mutations in Chinese populations is still largely unknown. We conducted a multi-center study to characterize the spectra of BRCA mutations in Chinese breast and ovarian cancer patients from Southern China.

METHODOLOGY/PRINCIPAL FINDINGS

A total of 651 clinically high-risk breast and/or ovarian cancer patients were recruited from the Hong Kong Hereditary Breast Cancer Family Registry from 2007 to 2011. Comprehensive BRCA1 and BRCA2 mutation screening was performed using bi-directional sequencing of all coding exons of BRCA1 and BRCA2. Sequencing results were confirmed by in-house developed full high resolution DNA melting (HRM) analysis. Among the 451 probands analyzed, 69 (15.3%) deleterious BRCA mutations were identified, comprising 29 in BRCA1 and 40 in BRCA2. The four recurrent BRCA1 mutations (c.470_471delCT, c.3342_3345delAGAA, c.5406+1_5406+3delGTA and c.981_982delAT) accounted for 34.5% (10/29) of all BRCA1 mutations in this cohort. The four recurrent BRCA2 mutations (c.2808_2811delACAA, c.3109C>T, c.7436_7805del370 and c.9097_9098insA) accounted for 40% (16/40) of all BRCA2 mutations. Haplotype analysis was performed to confirm 1 BRCA1 and 3 BRCA2 mutations are putative founder mutations. Rapid HRM mutation screening for a panel of the founder mutations were developed and validated.

CONCLUSION

In this study, our findings suggest that BRCA mutations account for a substantial proportion of hereditary breast/ovarian cancer in Southern Chinese population. Knowing the spectrum and frequency of the founder mutations in this population will assist in the development of a cost-effective rapid screening assay, which in turn facilitates genetic counseling and testing for the purpose of cancer risk assessment.

Characteristics and spectrum of BRCA1 and BRCA2 mutations in 3,922 Korean patients with breast and ovarian cancer

This investigation is aimed at evaluating the epidemiologic characteristics of BRCA1/2 germline mutations in Korean patients with breast and ovarian cancer (BOC). We analyzed the entire mutational data of BRCA1/2 genes in BOC patients who were tested in Korea since the first Korean report of BRCA1 mutation in 1995 with the exception of the data covered in the Korean Hereditary Breast Cancer (KOHBRA) study, the project launched in 2007 for establishing BRCA1/2 carrier cohorts in Korea. In total, BRCA1/2 gene mutations of 3,922 Korean BOC patients were evaluated, including the unpublished data of 2,139 breast cancer patients examined by four Korean institutions and the data of 1,783 BOC patients covered in ten previous reports. Overall, 420 (150 distinct) pathogenic mutations were identified, 211 (73 distinct) in BRCA1 and 209 (77 distinct) in BRCA2. The majority (134 of 150) of the distinct mutations resulted in premature termination codon of the BRCA1/2 translation. BRCA1 c.4186-1593_4676-1465del was the only large genomic rearrangements mutation. Out of 150 distinct BRCA1/2 mutations, 84 (56 %) mutations were considered specific to Korean BOC. Eighty-five BRCA1/2 mutations were detected in at least two unrelated patients. These recurrent mutations account for 84.5 % (355 of 420) of mutations detected in the Korean population. In the pooled mutational data of BRCA1/2 genes, this study discovered the prevalence of BRCA1/2 mutations in the Korean BOC patients is similar to those found in other ethnic groups. Large genomic rearrangements in BRCA1/2 genes were infrequently detected among the Korean patients with BOC. There were several BRCA1/2 mutation candidates for founder mutations. To further establish a Korean cohort for BRCA1/2 mutations, the nationwide KOHBRA study is in progress.

Polymorphisms in second intron of the FGFR2 gene are associated with the risk of early-onset breast cancer in Chinese Han women

Fibroblast growth factor receptor 2 (FGFR2) plays an important role in tumor cell growth, invasiveness, motility, and angiogenesis. Several single-nucleotide polymorphisms (SNPs) in the second intron of the FGFR2 gene are associated with the risk of breast cancer. In this study, we determined whether these SNPs of the FGFR2 gene are associated with early onset of non-familial breast cancer in a Chinese Han population. Recruited were 118 female breast cancer patients who were less than or equal to 35 years of age and without a family history of breast cancer, and 104 age-matched healthy controls. Six SNPs of the second intron of the FGFR2 gene, including rs2981428C/A (i.e., a change at this particular site from nucleotide C to A), rs11200014G/A, rs2981579C/T, rs1219648A/G, rs2420946C/T, and rs2981582C/T, were detected using matrix-assisted laser desorption/ionization mass spectrometry. The data showed that the homozygotes at each minor allele, rs11200014 (AA), rs1219648 (GG), rs2420946 (TT), and rs2981582 (TT), were significantly associated with an increased risk of early-onset non-familial breast cancer. The haplotype containing rs11200014A, rs1219648G, rs2420946T and rs2981582T also exhibited a significantly higher distribution in patients compared to controls (OR=1.784, 95% CI=1.161-2.744). In stratified analyses, each of the above four SNPs conferred a significantly greater risk of estrogen receptor-positive breast cancer, compared to estrogen receptor-negative breast cancer that is more resistant to treatment. Our data demonstrate that these four SNPs of the FGFR2 gene are associated with the risk of breast cancer at a young age in Chinese Han women.

Multimodel assessment of BRCA1 mutations in Taiwanese (ethnic Chinese) women with early-onset, bilateral or familial breast cancer

Although evidence suggests an importance of genetic factors in the development of breast cancer in Taiwanese (ethnic Chinese) women, including a high incidence of early-onset and secondary contralateral breast cancer, a major breast cancer predisposition gene, BRCA1, has not been well studied in this population. In fact, the carcinogenic impacts of many genetic variants of BRCA1 are unknown and classified as variants of uncertain significance (VUS). It is therefore important to establish a method to characterize the BRCA1 VUSs and understand their role in Taiwanese breast cancer patients. Accordingly, we developed a multimodel assessment strategy consisting of a prescreening portion and a validated functional assay to study breast cancer patients with early-onset, bilateral or familial breast cancer. We found germ-line BRCA1 mutations in 11.1% of our cohort and identified one novel missense mutation, c.5191C>A. Two genetic variants were initially classified as VUSs (c.1155C>T and c.5191C>A). c.1155C>T is not predicted to be deleterious in the prescreening portion of our assessment strategy. c.5191C>A, on the other hand, causes p.T1691K, which is predicted to have high deleterious probability because of significant structural alteration, a high deleterious score in the predictive programs and, clinically, triple negative characteristics in breast tumors. This mutant is confirmed by transcription activation and yeast growth-inhibition assays. In conclusion, we show as high a prevalence of germ-line BRCA1 mutation in high-risk Taiwanese patients as in Caucasians and demonstrate a useful strategy for studying BRCA1 VUSs.

Novel LOVD databases for hereditary breast cancer and colorectal cancer genes in the Chinese population

The Human Variome Project (HVP) is an international consortium of clinicians, geneticists, and researchers from over 30 countries, aiming to facilitate the establishment and maintenance of standards, systems, and infrastructure for the worldwide collection and sharing of all genetic variations effecting human disease. The HVP-China Node will build new and supplement existing databases of genetic diseases. As the first effort, we have created a novel variant database of BRCA1 and BRCA2, mismatch repair genes (MMR), and APC genes for breast cancer, Lynch syndrome, and familial adenomatous polyposis (FAP), respectively, in the Chinese population using the Leiden Open Variation Database (LOVD) format. We searched PubMed and some Chinese search engines to collect all the variants of these genes in the Chinese population that have already been detected and reported. There are some differences in the gene variants between the Chinese population and that of other ethnicities. The database is available online at http://www.genomed.org/LOVD/. Our database will appear to users who survey other LOVD databases (e.g., by Google search, or by NCBI GeneTests search). Remote submissions are accepted, and the information is updated monthly.

Prevalence and characterization of BRCA1 and BRCA2 germline mutations in Chinese women with familial breast cancer

Although there are some studies to investigate germline mutations in BRCA1/2 genes in Chinese women with familial breast cancer, many of them suffer relatively small sample size. In this study, we screened germline mutations in BRCA1/2 genes in a cohort of 409 Chinese women with familial breast cancer from north China by using a PCR-sequencing assay. A total of 43 deleterious mutations in BRCA1/2 genes were identified in this cohort, including 17 novel mutations and 6 recurrent mutations. The frequencies of BRCA1 and BRCA2 mutations were 3.9% (16/409) and 6.6% (27/409), respectively; the mutation rate of BRCA2 was 1.7-fold higher than that of BRCA1. The entire mutation rate of BRCA1/2 was 10.5% in this cohort; however, the mutation rate of BRCA1/2 genes was 23.0% in 78 familial breast cancer patients whose tumors were diagnosed at or before the age of 40. The mean age at diagnosis of breast cancer in BRCA1 carriers (42.8 years) and BRCA2 carriers (45.1 years) was younger than non-carriers (51.0 years) in this cohort (P = 0.005; P = 0.01, respectively). In addition, both BRCA1 carriers and BRCA2 carriers were more likely to exhibit triple-negative breast cancer (ER-, PgR-, and HER2-) than non-carriers (BRCA1 carriers vs. non-carriers, 69.2 vs. 23.0%, P = 0.001; BRCA2 carriers vs. non-carriers, 45.8 vs. 23.0%, P = 0.01). Our study suggested that the spectrum and characteristics of BRCA1/2 mutations in Chinese familial breast cancer exhibit some unique features, and Chinese women with familial breast cancer whose tumors are diagnosed at or before the age of 40 are good candidates for BRCA1/2 testing.

Family history, BRCA mutations and breast cancer in Vietnamese women

The purpose of this report is to estimate the proportions of familial and hereditary breast cancers among unselected cases of breast cancer in Vietnam. Two hundred and ninety-two unselected cases of incident breast cancer were recruited from the National Cancer Hospital, Hanoi, the largest cancer centre in Vietnam. Family histories were collected for 292 cases and a DNA sample was obtained for 259 cases. DNA samples were screened for mutations in the large exons of BRCA1 and BRCA2 using the protein truncation test and by allele-specific testing for 17 founder mutations which have been reported in other Asian populations. Complete gene sequencing was performed on two cases of familial breast cancer. Seven of 292 cases reported a relative with breast cancer and one patient reported a relative with ovarian cancer. A pathogenic BRCA mutation was detected in 2 of 259 cases; one BRCA1 carrier was diagnosed at age 51 and one BRCA2 carrier was diagnosed at age 42. Neither case reported a relative with breast or ovarian cancer. A family history of breast cancer is very uncommon among Vietnamese breast cancer patients. The frequency of pathogenic BRCA mutations in Vietnamese breast cancer patients is among the lowest reported worldwide.

Clinical and pathological characteristics of Chinese patients with BRCA related breast cancer

Breast cancers related to BRCA mutations are associated with particular biological features. Here we report the clinical and pathological characteristics of breast cancer in Chinese women with and without BRCA mutations and of carriers of BRCA1 mutations compared to BRCA2 mutations. Two hundred and 26 high-risk Hong Kong Chinese women were tested for BRCA mutations, medical information was obtained from medical records, and risk and demographic information was obtained from personal interviews. In this cohort, 28 (12.4%) women were BRCA mutation carriers and among these carriers, 39.3% were BRCA1 and 60.7% were BRCA2 mutations. Mutation carriers were more likely to have a familial history of breast and ovarian cancer, high-grade cancers, and triple negative (TN) cancers. Prevalence of TN was 48.3% in BRCA carriers and 25.6% in non-carriers and was 67.7% in BRCA1 and 35.3% in BRCA2 carriers. Estrogen receptor (ER) negative cancer was significantly associated with BRCA1 mutations, especially in those under 40 years of age. BRCA-related breast cancer in this Chinese population is associated with family history and adverse pathological/prognostic features, with BRCA2 mutations being more prevalent but BRCA1 carriers having more aggressive and TN cancers. Compared to Caucasian populations, prevalence of BRCA2 mutations and TN cancer in BRCA2 mutation carriers in Chinese population are elevated.