chr13-32316421-G-C

Variant names:

• chr13-32316421-G-C
• NM_000059.4:c.-39-1G>C

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000059.4(BRCA2):​c.-39-1G>C variant causes a splice acceptor, intron change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: BRCA2 NM_000059.4 splice_acceptor, intron
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 4.97

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 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 13-32316421-G-C is Pathogenic according to our data. Variant chr13-32316421-G-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1067980.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BRCA2	NM_000059.4	c.-39-1G>C		splice_acceptor_variant, intron_variant	Intron 1 of 26	ENST00000380152.8	NP_000050.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
BRCA2	ENST00000380152.8	c.-39-1G>C		splice_acceptor_variant, intron_variant	Intron 1 of 26	5	NM_000059.4	ENSP00000369497.3
BRCA2	ENST00000530893.7	c.-404-1G>C		splice_acceptor_variant, intron_variant	Intron 1 of 26	1		ENSP00000499438.2
BRCA2	ENST00000614259.2	n.-40G>C		upstream_gene_variant		2		ENSP00000506251.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 26

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Breast-ovarian cancer, familial, susceptibility to, 2 Pathogenic:1

Jun 06, 2023

KCCC/NGS Laboratory, Kuwait Cancer Control Center

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

A likely pathogenic variant in the BRCA2 gene was detected (c.-39-1G>C). This sequence change affects an acceptor splice site in intron 1 of the BRCA2 gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. A variant affecting the same splicesite (c.-39-1_-39del) has been observed in individuals affected with breast cancer (PMID: 26187060, 28993434), as well as an individual affected with medulloblastoma (PMID: 29753700). ClinVar contains an entry for this variant (Variation ID: 403704). Donor and acceptor splice site variants typically lead to a loss of protein function (PMID: 28905878), and loss-of-function variants in BRCA2 are known to be pathogenic (PMID: 20104584). Therefore, this variant has been classified as Likely Pathogenic. -

Hereditary breast ovarian cancer syndrome Pathogenic:1

Sep 09, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects an acceptor splice site in intron 1 of the BRCA2 gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Experimental studies have shown that disruption of this splice site results in aberrant skipping of exon 2 and aberrant combined skipping of exons 2-3 (PMID: 28905878). Disruption of this splice site has been observed in individual(s) with breast cancer (PMID: 26187060, 28993434, 21520333, Invitae). This variant is not present in population databases (ExAC no frequency). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Pathogenic	0.18
CADD	Pathogenic	33
DANN	Uncertain	0.99

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.97		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.97		Position offset: 1
DS_DG_spliceai		0.31		Position offset: -30

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr13-32890558;