chr13-32363178-G-T

Position:

• chr13-32363178-G-T

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.7977-1G>T variant causes a splice acceptor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000658 in 152,072 control chromosomes in the GnomAD database, with no homozygous occurrence. 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: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: BRCA2 NM_000059.4 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 9.52

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 13-32363178-G-T is Pathogenic according to our data. Variant chr13-32363178-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 126163.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr13-32363178-G-T is described in Lovd as [Pathogenic]. Variant chr13-32363178-G-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BRCA2	NM_000059.4	c.7977-1G>T		splice_acceptor_variant		ENST00000380152.8	NP_000050.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BRCA2	ENST00000380152.8	c.7977-1G>T		splice_acceptor_variant		5	NM_000059.4	ENSP00000369497	A2

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 152072 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000192

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 31

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 152072 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74274

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000192

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Apr 25, 2019	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Ambry Genetics	Jul 17, 2023	The c.7977-1G>T intronic variant results from a G to T substitution one nucleotide upstream from coding exon 17 of the BRCA2 gene. This variant has been identified in cohorts of ethnic Chinese individuals with indications for genetic testing for hereditary breast and ovarian cancer (Bhaskaran SP et al. Int J Cancer, 2019 Aug;145:962-973; Gao X et al. Hum Mutat, 2020 Mar;41:696-708). This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice acceptor site. RNA studies have demonstrated that this alteration results in abnormal splicing in the set of samples tested (Fraile-Bethencourt E et al. PLoS Genet, 2017 Mar;13:e1006691; Mesman RLS et al. Genet Med, 2020 Aug;22:1355-1365; Ambry internal data). In addition, this alteration failed to rescue the loss of Brca2 activity in an assay of cell survival in murine embryonic stem cells (Mesman RLS et al. Genet Med, 2020 Aug;22:1355-1365). Alterations that disrupt the canonical splice site are expected to cause aberrant splicing, resulting in an abnormal protein or a transcript that is subject to nonsense-mediated mRNA decay. As such, this alteration is classified as likely pathogenic. -

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

Pathogenic, no assertion criteria provided

clinical testing

Breast Cancer Information Core (BIC) (BRCA2)

Nov 30, 1998

- -

Hereditary breast ovarian cancer syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 07, 2023

For these reasons, this variant has been classified as Pathogenic. Studies have shown that disruption of this splice site alters mRNA splicing and is expected to lead to the loss of protein expression (PMID: 16211554, 22006311, 28339459). ClinVar contains an entry for this variant (Variation ID: 126163). Disruption of this splice site has been observed in individual(s) with breast and/or ovarian cancer (PMID: 28961279, 30702160). This variant is present in population databases (rs81002874, gnomAD 0.06%). This sequence change affects an acceptor splice site in intron 17 of the BRCA2 gene. RNA analysis indicates that disruption of this splice site induces altered splicing and may result in an absent or disrupted protein product. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.33
CADD	Pathogenic	32
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
MutationTaster	Benign	1.0	D;D
GERP RS		4.9

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.98		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.98		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: rs81002874; hg19: chr13-32937315;