chr13-32396896-A-C

Position:

• chr13-32396896-A-C

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.9502-2A>C variant causes a splice acceptor, intron change. The variant allele was found at a frequency of 0.00000137 in 1,461,732 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: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: BRCA2 NM_000059.4 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:8
• Conservation: PhyloP100: 5.31

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]

BRCA2 (HGNC:):

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 0.0142341815 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 13-32396896-A-C is Pathogenic according to our data. Variant chr13-32396896-A-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 52858.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr13-32396896-A-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BRCA2	NM_000059.4	c.9502-2A>C		splice_acceptor_variant, intron_variant		ENST00000380152.8	NP_000050.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BRCA2	ENST00000380152.8	c.9502-2A>C		splice_acceptor_variant, intron_variant		5	NM_000059.4	ENSP00000369497.3
BRCA2	ENST00000530893.7	c.9133-2A>C		splice_acceptor_variant, intron_variant		1		ENSP00000499438.2
BRCA2	ENST00000614259.2	n.*1560-2A>C		splice_acceptor_variant, intron_variant		2		ENSP00000506251.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251232 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135798

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000881

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461732 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727180

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:8

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Pathogenic:3

Likely pathogenic, criteria provided, single submitter	clinical testing	Ambry Genetics	Nov 16, 2023	The c.9502-2A>C intronic variant results from an A to C substitution 2 nucleotides before coding exon 25 in the BRCA2 gene. This variant was previously reported in the SNPDatabase as rs81002868. Based on nucleotide sequence alignment, this position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice acceptor site and will result in the creation or strengthening of a novel splice acceptor site. Further, functional analysis of this alteration using a minigene construct is predicted to cause a combination of frameshifting partial intron inclusion as well as an in-frame deletion coding exon 25 (also called exon 26 in the literature) (Acedo A et al, Hum. Mutat. 2015 Feb; 36(2):210-21). Based on the majority of available evidence to date, this variant is likely to be pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Nov 16, 2021	This variant causes an A to C nucleotide substitution at the -2 position of intron 25 of the BRCA2 gene. Splice site prediction tools predict that this variant may have a significant impact on RNA splicing (PMID: 21523855). An RNA study utilizing a mini-gene assay have shown that this variant results in multiple aberrant transcripts causing both in-frame skipping of exon 26 and protein frameshift mutations via the use of cryptic acceptor sites (PMID: 25382762). This variant has been reported in an individual affected with breast cancer (PMID: 33471991; Leiden Open Variation Database DB-ID BRCA2_006242). This variant has been identified in 1/251232 chromosomes in the general population by the Genome Aggregation Database (gnomAD). Loss of BRCA2 function is a known mechanism of disease (clinicalgenome.org). Based on the available evidence, this variant is classified as Likely Pathogenic. -
Likely pathogenic, criteria provided, single submitter	curation	Sema4, Sema4	Sep 19, 2021	- -

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

Pathogenic, no assertion criteria provided	clinical testing	Breast Cancer Information Core (BIC) (BRCA2)	Dec 23, 2003	- -
Pathogenic, criteria provided, single submitter	clinical testing	Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA), c/o University of Cambridge	Oct 02, 2015	- -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Quest Diagnostics Nichols Institute San Juan Capistrano

Aug 10, 2023

The BRCA2 c.9502-2A>C variant disrupts a canonical splice-acceptor site and is predicted to interfere with normal BRCA2 mRNA splicing. This variant has been reported in the published literature in an individual with epithelial ovarian cancer (PMID: 36169650 (2022)) and in individual(s) with BRCA2-related conditions (PMID: 29446198 (2018)). In a large-scale breast cancer association study, the variant was observed in an individual with breast cancer (PMID: 33471991 (2021), see also LOVD (http://databases.lovd.nl/shared/genes/BRCA2)). This variant was shown to cause exon 26 skipping and produces aberrant transcripts which may have consequences with BRCA2 binding to TP53 (PMID: 25382762 (2015)). The frequency of this variant in the general population, 0.000004 (1/251232 chromosomes (Genome Aggregation Database, http://gnomad.broadinstitute.org)), is uninformative in the assessment of its pathogenicity. Based on the available information, this variant is classified as likely pathogenic. -

Familial cancer of breast Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Baylor Genetics

Nov 09, 2023

- -

Hereditary breast ovarian cancer syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 31, 2023

For these reasons, this variant has been classified as Pathogenic. Studies have shown that disruption of this splice site is associated with altered splicing resulting in multiple RNA products (PMID: 25382762). ClinVar contains an entry for this variant (Variation ID: 52858). Disruption of this splice site has been observed in individual(s) with clinical features of BRCA2-related conditions (PMID: 29446198). This variant is present in population databases (rs81002868, gnomAD 0.0009%). This sequence change affects an acceptor splice site in intron 25 of the BRCA2 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in BRCA2 are known to be pathogenic (PMID: 20104584). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.080
CADD	Pathogenic	33
DANN	Uncertain	0.98
Eigen	Pathogenic	0.99
Eigen_PC	Pathogenic	0.83
FATHMM_MKL	Pathogenic	0.99	D
GERP RS		5.9

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.92
SpliceAI score (max)		0.98		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.50		Position offset: 27
DS_AL_spliceai		0.98		Position offset: 2

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

Publications

LitVar

Other links and lift over

dbSNP: rs81002868; hg19: chr13-32971033;