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Identification of a new BRCA2 large genomic deletion associated with high risk male breast cancer.

Timoteo AR, Albuquerque BM, Moura PC, Ramos CC, Agnez-Lima LF, Walsh T, King MC, Lajus TB - Hered Cancer Clin Pract (2015)

Bottom Line: Large rearrangements in BRCA1 and BRCA2 occur in a small percentage (<1%) of patients tested for hereditary breast and ovarian cancer.Mutation segregation analysis should be further done in the Brazilian population.Herein we highlight the importance of next-generation sequencing in the detection of large genomic deletions.

View Article: PubMed Central - PubMed

Affiliation: Universidade Federal do Rio Grande do Norte, Av. Senador Salgado Filho, s/n, Natal, RN Brazil.

ABSTRACT

Background: Male breast cancer (MBC) is an uncommon disease that has been the focus of limited research. It is estimated that approximately 10% of men with breast cancer have a genetic predisposition, with BRCA2 being the most prevalent genetic mutation. Here we describe the case of MBC in a 64-year-old man who presented on physical examination a nodule in his left breast and declared to have an extensive family history of cancer.

Methods and results: The patient was firstly diagnosed with an invasive ductal carcinoma (IDC) with histological grade III, nuclear grade 3, pT4N2Mx and positive for hormonal receptors and HER2. Exome sequencing was performed by massive parallel sequencing which had detected a novel BRCA2 germline mutation that is a large genomic deletion of 3,492 nucleotides including BRCA2 exon 14, and this deletion is out of frame and is predicted to lead to a stop codon in exon 15 at codon 2,496.

Conclusion: Large rearrangements in BRCA1 and BRCA2 occur in a small percentage (<1%) of patients tested for hereditary breast and ovarian cancer. This is the first report of the mutation del3492 in BRCA2 exon 14, which leads to a truncated protein and therefore is clinically relevant. Mutation segregation analysis should be further done in the Brazilian population. Herein we highlight the importance of next-generation sequencing in the detection of large genomic deletions.

No MeSH data available.


Related in: MedlinePlus

Mutation effect at transcript level. Agarose gel (1,5%) showing no amplification of proband’s samples using a forward primer in exon 13 and a reverse primer in exon 15 of BRCA2. Total cDNA from two independent RNA extractions from MRC5-V1 cells was used as a positive control for fragment amplification. A total of 70 ng from cDNA was used in each reaction. The length of the fragment expected is 530 bp.
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Fig4: Mutation effect at transcript level. Agarose gel (1,5%) showing no amplification of proband’s samples using a forward primer in exon 13 and a reverse primer in exon 15 of BRCA2. Total cDNA from two independent RNA extractions from MRC5-V1 cells was used as a positive control for fragment amplification. A total of 70 ng from cDNA was used in each reaction. The length of the fragment expected is 530 bp.

Mentions: A large heterozygous genomic deletion was identified, predicted by read-depth analysis of BROCA sequence to be chr13: 32,926,826 to 32,930,318 (hg19). A 3,492 nucleotide deletion was detected at BRCA2 sequence, BRCA2_g.26826_30318del, including exon 14, which is out of frame and is predicted to lead to a stop in exon 15 at codon 2,496. To analyze the mutation effect at transcript level, RNA was extracted from FFPE (formalin fixed paraffin embedded) samples of normal and tumour tissue followed by RT-PCR reaction. The PCR was performed utilizing primers against 13 and 15 BRCA2 exons forward and reverse, respectively (13 F-GCCGATTACCTGTGTACCCT; 15 F-GAAAGACGCGTTGCCTTTGT). No amplification was observed in the proband’s samples while for the controls (70 ng from cDNA from MRC5-V1 cells) a 530 bp product was amplified, as expected (Figure 4), showing that the deletion is present in both tissues. BRCA2 gene has 27 exons and there are 14,823 mutations related in the BIC database. In BRCA2 exon 14, there are a total of 624 entries for mutations, of which 76 are distinct mutations, polymorphisms and variants and 40 alterations reported only once. The majority of mutations found to date in the BRCA1/BRCA2 genes in breast and/or ovarian cancer families are point mutations or small insertions and deletions scattered over the coding sequence and splice junctions. Large rearrangements in BRCA1 and BRCA2 occur in a small percentage (<1%) of patients tested for hereditary breast and ovarian cancer [15]. Moreover, the mutation was detected in a male patient.Figure 4


Identification of a new BRCA2 large genomic deletion associated with high risk male breast cancer.

Timoteo AR, Albuquerque BM, Moura PC, Ramos CC, Agnez-Lima LF, Walsh T, King MC, Lajus TB - Hered Cancer Clin Pract (2015)

Mutation effect at transcript level. Agarose gel (1,5%) showing no amplification of proband’s samples using a forward primer in exon 13 and a reverse primer in exon 15 of BRCA2. Total cDNA from two independent RNA extractions from MRC5-V1 cells was used as a positive control for fragment amplification. A total of 70 ng from cDNA was used in each reaction. The length of the fragment expected is 530 bp.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4308828&req=5

Fig4: Mutation effect at transcript level. Agarose gel (1,5%) showing no amplification of proband’s samples using a forward primer in exon 13 and a reverse primer in exon 15 of BRCA2. Total cDNA from two independent RNA extractions from MRC5-V1 cells was used as a positive control for fragment amplification. A total of 70 ng from cDNA was used in each reaction. The length of the fragment expected is 530 bp.
Mentions: A large heterozygous genomic deletion was identified, predicted by read-depth analysis of BROCA sequence to be chr13: 32,926,826 to 32,930,318 (hg19). A 3,492 nucleotide deletion was detected at BRCA2 sequence, BRCA2_g.26826_30318del, including exon 14, which is out of frame and is predicted to lead to a stop in exon 15 at codon 2,496. To analyze the mutation effect at transcript level, RNA was extracted from FFPE (formalin fixed paraffin embedded) samples of normal and tumour tissue followed by RT-PCR reaction. The PCR was performed utilizing primers against 13 and 15 BRCA2 exons forward and reverse, respectively (13 F-GCCGATTACCTGTGTACCCT; 15 F-GAAAGACGCGTTGCCTTTGT). No amplification was observed in the proband’s samples while for the controls (70 ng from cDNA from MRC5-V1 cells) a 530 bp product was amplified, as expected (Figure 4), showing that the deletion is present in both tissues. BRCA2 gene has 27 exons and there are 14,823 mutations related in the BIC database. In BRCA2 exon 14, there are a total of 624 entries for mutations, of which 76 are distinct mutations, polymorphisms and variants and 40 alterations reported only once. The majority of mutations found to date in the BRCA1/BRCA2 genes in breast and/or ovarian cancer families are point mutations or small insertions and deletions scattered over the coding sequence and splice junctions. Large rearrangements in BRCA1 and BRCA2 occur in a small percentage (<1%) of patients tested for hereditary breast and ovarian cancer [15]. Moreover, the mutation was detected in a male patient.Figure 4

Bottom Line: Large rearrangements in BRCA1 and BRCA2 occur in a small percentage (<1%) of patients tested for hereditary breast and ovarian cancer.Mutation segregation analysis should be further done in the Brazilian population.Herein we highlight the importance of next-generation sequencing in the detection of large genomic deletions.

View Article: PubMed Central - PubMed

Affiliation: Universidade Federal do Rio Grande do Norte, Av. Senador Salgado Filho, s/n, Natal, RN Brazil.

ABSTRACT

Background: Male breast cancer (MBC) is an uncommon disease that has been the focus of limited research. It is estimated that approximately 10% of men with breast cancer have a genetic predisposition, with BRCA2 being the most prevalent genetic mutation. Here we describe the case of MBC in a 64-year-old man who presented on physical examination a nodule in his left breast and declared to have an extensive family history of cancer.

Methods and results: The patient was firstly diagnosed with an invasive ductal carcinoma (IDC) with histological grade III, nuclear grade 3, pT4N2Mx and positive for hormonal receptors and HER2. Exome sequencing was performed by massive parallel sequencing which had detected a novel BRCA2 germline mutation that is a large genomic deletion of 3,492 nucleotides including BRCA2 exon 14, and this deletion is out of frame and is predicted to lead to a stop codon in exon 15 at codon 2,496.

Conclusion: Large rearrangements in BRCA1 and BRCA2 occur in a small percentage (<1%) of patients tested for hereditary breast and ovarian cancer. This is the first report of the mutation del3492 in BRCA2 exon 14, which leads to a truncated protein and therefore is clinically relevant. Mutation segregation analysis should be further done in the Brazilian population. Herein we highlight the importance of next-generation sequencing in the detection of large genomic deletions.

No MeSH data available.


Related in: MedlinePlus