Dataset Information

Minor role of BRCA2 mutation (Exon2 and Exon11) in patients with early-onset breast cancer amongst Iranian Azeri-Turkish women.

ABSTRACT: OBJECTIVE(S):Breast cancer is the most common cancer in women. Every year, one million new cases are reported worldwide, representing 18% of the total number of cancer in women. Hereditary BRCA1 and BRCA2 mutations account for about 60% of inherited breast cancer and are the only known causes of hereditary breast cancer syndrome. The aim of this study was to determine the frequency of BRCA2 (exon2 and exon11) gene mutation in patients with early-onset breast cancer among Iranian Azeri-Turkish women. MATERIALS AND METHODS:We obtained clinical information, family history and peripheral blood from 110 women under the age of 45 with early-onset breast cancer for scanning germline mutations in the exon2 and 11 of BRCA2 genes which comprises over 50% of the gene. Single-strand conformation polymorphism assay was used in order for screening potential mutations on amplified regions followed by direct sequencing analysis to determine the genotypes. RESULTS:Overall, 11 sequence variants were identified in this study group, including four homozygotes and seven heterozygotes silent substitution of c.3807T to C, p.Val1269Val (rs543304). CONCLUSION:Mutations in BRCA2 were surprisingly infrequent in the early onset breast cancer patients among Iranian Azeri-Turkish women.

SUBMITTER: Karimian Fathi N

PROVIDER: S-EPMC3976747 | biostudies-literature | 2014 Feb

REPOSITORIES: biostudies-literature

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Minor role of BRCA2 mutation (Exon2 and Exon11) in patients with early-onset breast cancer amongst Iranian Azeri-Turkish women.

Karimian Fathi Nahid N Shekari Khaniani Mahmood M Montazeri Vahid V Mansoori Derakhshan Sima S

Iranian journal of basic medical sciences 20140201 2

<h4>Objective(s)</h4>Breast cancer is the most common cancer in women. Every year, one million new cases are reported worldwide, representing 18% of the total number of cancer in women. Hereditary BRCA1 and BRCA2 mutations account for about 60% of inherited breast cancer and are the only known causes of hereditary breast cancer syndrome. The aim of this study was to determine the frequency of BRCA2 (exon2 and exon11) gene mutation in patients with early-onset breast cancer among Iranian Azeri-Tu ...[more]

PMID: 24711893

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Project description:INTRODUCTION:Cis-acting regulatory single nucleotide polymorphisms (SNPs) at specific loci may modulate penetrance of germline mutations at the same loci by introducing different levels of expression of the wild-type allele. We have previously reported that BRCA2 shows differential allelic expression and we hypothesize that the known variable penetrance of BRCA2 mutations might be associated with this mechanism. METHODS:We combined haplotype analysis and differential allelic expression of BRCA2 in breast tissue to identify expression haplotypes and candidate cis-regulatory variants. These candidate variants underwent selection based on in silico predictions for regulatory potential and disruption of transcription factor binding, and were functionally analyzed in vitro and in vivo in normal and breast cancer cell lines. SNPs tagging the expression haplotypes were correlated with the total expression of several genes in breast tissue measured by Taqman and microarray technologies. The effect of the expression haplotypes on breast cancer risk in BRCA2 mutation carriers was investigated in 2,754 carriers. RESULTS:We identified common haplotypes associated with differences in the levels of BRCA2 expression in human breast cells. We characterized three cis-regulatory SNPs located at the promoter and two intronic regulatory elements which affect the binding of the transcription factors C/EBP?, HMGA1, D-binding protein (DBP) and ZF5. We showed that the expression haplotypes also correlated with changes in the expression of other genes in normal breast. Furthermore, there was suggestive evidence that the minor allele of SNP rs4942440, which is associated with higher BRCA2 expression, is also associated with a reduced risk of breast cancer (per-allele hazard ratio (HR) = 0.85, 95% confidence interval (CI) = 0.72 to 1.00, P-trend = 0.048). CONCLUSIONS:Our work provides further insights into the role of cis-regulatory variation in the penetrance of disease-causing mutations. We identified small-effect genetic variants associated with allelic expression differences in BRCA2 which could possibly affect the risk in mutation carriers through altering expression levels of the wild-type allele.

Project description:Introduction: Cis-acting regulatory single nucleotide polymorphisms (SNPs) at specific loci may modulate penetrance of germline mutations at the same loci by introducing different levels of expression of the wild-type allele. We have previously reported that BRCA2 shows differential allelic expression and we hypothesize that the known variable penetrance of BRCA2 mutations might be associated with this mechanism. Methods: We combined haplotype analysis and differential allelic expression of BRCA2 in breast tissue to identify expression haplotypes and candidate cis-regulatory variants. These candidate variants underwent selection based on in-silico predictions for regulatory potential and disruption of transcription factor binding, and were functionally analysed in-vitro and in-vivo in normal and breast cancer cell lines. SNPs tagging the expression haplotypes were correlated with the total expression of several genes in breast tissue measured by Taqman and microarray technologies. The effect of the expression haplotypes on breast cancer risk in BRCA2 mutation carriers was investigated in 2754 carriers. Results: We identified common haplotypes associated with differences in the levels of BRCA2 expression in human breast cells. We characterised three cis-regulatory SNPs located at the promoter and two intronic regulatory elements, which affect the binding of the transcription factors C/EBPα, HMGA1, DBP and ZF5. We showed that the expression haplotypes also correlated with changes in the expression of other genes in normal breast. Furthermore, there was suggestive evidence that the minor allele of SNP rs4942440, which is associated with higher BRCA2 expression, is also associated with a reduced risk of breast cancer (per-allele HR=0.85, 95%CI=0.72-1.00, P-trend=0.048). Conclusion: Our work provides further insights into the role of cis-regulatory variation in the penetrance of disease-causing mutations. We identified small-effect genetic variants associated with allelic expression differences in BRCA2, which could possibly affect the risk in mutation carriers through altering expression levels of the wild-type allele. Total gene expression of normal breast sample from healthy controls. This submission represents transcriptome component of study.

Project description:Introduction: Cis-acting regulatory single nucleotide polymorphisms (SNPs) at specific loci may modulate penetrance of germline mutations at the same loci by introducing different levels of expression of the wild-type allele. We have previously reported that BRCA2 shows differential allelic expression and we hypothesize that the known variable penetrance of BRCA2 mutations might be associated with this mechanism. Methods: We combined haplotype analysis and differential allelic expression of BRCA2 in breast tissue to identify expression haplotypes and candidate cis-regulatory variants. These candidate variants underwent selection based on in-silico predictions for regulatory potential and disruption of transcription factor binding, and were functionally analysed in-vitro and in-vivo in normal and breast cancer cell lines. SNPs tagging the expression haplotypes were correlated with the total expression of several genes in breast tissue measured by Taqman and microarray technologies. The effect of the expression haplotypes on breast cancer risk in BRCA2 mutation carriers was investigated in 2754 carriers. Results: We identified common haplotypes associated with differences in the levels of BRCA2 expression in human breast cells. We characterised three cis-regulatory SNPs located at the promoter and two intronic regulatory elements, which affect the binding of the transcription factors C/EBPα, HMGA1, DBP and ZF5. We showed that the expression haplotypes also correlated with changes in the expression of other genes in normal breast. Furthermore, there was suggestive evidence that the minor allele of SNP rs4942440, which is associated with higher BRCA2 expression, is also associated with a reduced risk of breast cancer (per-allele HR=0.85, 95%CI=0.72-1.00, P-trend=0.048). Conclusion: Our work provides further insights into the role of cis-regulatory variation in the penetrance of disease-causing mutations. We identified small-effect genetic variants associated with allelic expression differences in BRCA2, which could possibly affect the risk in mutation carriers through altering expression levels of the wild-type allele. Genotype of normal breast sample from healthy controls.

Dataset Information

Minor role of BRCA2 mutation (Exon2 and Exon11) in patients with early-onset breast cancer amongst Iranian Azeri-Turkish women.

Publications

Minor role of BRCA2 mutation (Exon2 and Exon11) in patients with early-onset breast cancer amongst Iranian Azeri-Turkish women.

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