13-32362694-G-T

Variant names:

• chr13-32362694-G-T
• rs81002873
• NM_000059.4:c.7976+1G>T

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1_Moderate PM2 PP5_Very_Strong

The NM_000059.4(BRCA2):​c.7976+1G>T variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: BRCA2 NM_000059.4 splice_donor, intron
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 9.89

Genes affected

BRCA2 (HGNC:1101): (BRCA2 DNA repair associated) Inherited mutations in BRCA1 and this gene, BRCA2, confer increased lifetime risk of developing breast or ovarian cancer. Both BRCA1 and BRCA2 are involved in maintenance of genome stability, specifically the homologous recombination pathway for double-strand DNA repair. The largest exon in both genes is exon 11, which harbors the most important and frequent mutations in breast cancer patients. The BRCA2 gene was found on chromosome 13q12.3 in human. The BRCA2 protein contains several copies of a 70 aa motif called the BRC motif, and these motifs mediate binding to the RAD51 recombinase which functions in DNA repair. BRCA2 is considered a tumor suppressor gene, as tumors with BRCA2 mutations generally exhibit loss of heterozygosity (LOH) of the wild-type allele. [provided by RefSeq, May 2020]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.016671542 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 13-32362694-G-T is Pathogenic according to our data. Variant chr13-32362694-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 664938.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr13-32362694-G-T is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BRCA2	NM_000059.4	c.7976+1G>T		splice_donor_variant, intron_variant	Intron 17 of 26	ENST00000380152.8	NP_000050.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
BRCA2	ENST00000380152.8	c.7976+1G>T		splice_donor_variant, intron_variant	Intron 17 of 26	5	NM_000059.4	ENSP00000369497.3
BRCA2	ENST00000530893.7	c.7607+1G>T		splice_donor_variant, intron_variant	Intron 17 of 26	1		ENSP00000499438.2
BRCA2	ENST00000614259.2	n.*34+1G>T		splice_donor_variant, intron_variant	Intron 16 of 25	2		ENSP00000506251.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Oct 01, 2022

CeGaT Center for Human Genetics Tuebingen

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Oct 23, 2020

Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Hereditary cancer-predisposing syndrome Pathogenic:1

Apr 19, 2022

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.7976+1G>T intronic pathogenic mutation results from a G to T substitution one nucleotide after coding exon 16 of the BRCA2 gene. Alterations that disrupt the canonical splice site are expected to result in aberrant splicing. In silico splice site analysis predicts that this alteration will weaken the native splice donor site. The resulting transcript is predicted to be in-frame and is not expected to trigger nonsense-mediated mRNAdecay; however, direct evidence is unavailable. The exact functional effect of the altered amino acid sequence is unknown; however, the impacted region is critical for protein function (Ambry internal data). This alteration has been reported with a carrier frequency of 0.00013 in 7,636 unselected prostate cancer patients and absent in 12,366 male controls of Japanese ancestry (Momozawa Y et al. J Natl Cancer Inst, 2020 04;112:369-376). Several other alterations impacting the same donor site (BRCA2 c.7976+1G>A, BRCA2 c.7976+2C>G, BRCA2 c.7976+5G>A, BRCA2 c.7976+5G>T, BRCA2 c.7976G>A) has been shown to have a similar impact on splicing in (Casadei S et al. Proc Natl Acad Sci U S A, 2019 Dec; Wong MS et al. Mol Cell, 2018 09;71:1012-1026.e3; Montalban G et al. Hum Mutat, 2018 09;39:1155-1160; Fraile-Bethencourt E et al. PLoS Genet. 2017 Mar;13(3):e1006691). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -

Hereditary breast ovarian cancer syndrome Pathogenic:1

Oct 28, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. This sequence change affects a donor splice site in intron 17 of the BRCA2 gene. RNA analysis indicates that disruption of this splice site induces altered splicing and likely results in a shortened protein product. This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individual(s) with a personal or family history of breast and/or ovarian cancer (PMID: 18703817, 31528241). ClinVar contains an entry for this variant (Variation ID: 664938). Studies have shown that disruption of this splice site results in skipping of exon 17, but is expected to preserve the integrity of the reading-frame (PMID: 28339459, 31191615). This variant disrupts a region of the BRCA2 protein in which other variant(s) (p.Leu2653Pro) have been determined to be pathogenic (PMID: 17924331, 19043619, 21990134, 22678057, 23108138). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it are likely to be disease-causing. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.37
CADD	Pathogenic	33
DANN	Uncertain	1.0
Eigen	Pathogenic	1.3
Eigen_PC	Pathogenic	1.2
FATHMM_MKL	Pathogenic	0.98	D
GERP RS		5.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.93		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.93		Position offset: -1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs81002873; hg19: chr13-32936831;