rs886040954

Positions:

• chr13-32394687-A-G
• chr13-32394687-A-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PVS1_Moderate PM2 PP5

The NM_000059.4(BRCA2):​c.9257-2A>G variant causes a splice acceptor, intron change. The variant allele was found at a frequency of 0.00000137 in 1,460,418 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 Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: BRCA2 NM_000059.4 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:7 U:1
• Conservation: PhyloP100: 6.06

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 Uncertain_significance. Variant got 5 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.023788633 fraction of the gene. Cryptic splice site detected, with MaxEntScore 4.3, offset of 27, new splice context is: ccctttcgtctatttgtcAGacg. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 13-32394687-A-G is Pathogenic according to our data. Variant chr13-32394687-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 267722.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Pathogenic=5, Likely_pathogenic=2}. Variant chr13-32394687-A-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BRCA2	NM_000059.4	c.9257-2A>G		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.9257-2A>G		splice_acceptor_variant, intron_variant		5	NM_000059.4	ENSP00000369497.3
BRCA2	ENST00000530893.7	c.8888-2A>G		splice_acceptor_variant, intron_variant		1		ENSP00000499438.2
BRCA2	ENST00000614259.2	n.*1315-2A>G		splice_acceptor_variant, intron_variant		2		ENSP00000506251.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1460418 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 726456

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.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:7 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Hereditary breast ovarian cancer syndrome Pathogenic:2 Uncertain:1

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jul 10, 2023	Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. This sequence change affects an acceptor splice site in intron 24 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). This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individual(s) with breast and/or ovarian cancer (Invitae). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 267722). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 09, 2021	Variant summary: BRCA2 c.9257-2A>G is located in a canonical splice-site and is predicted to affect mRNA splicing resulting in a significantly altered protein due to either exon skipping, shortening, or inclusion of intronic material. Several computational tools predict a significant impact on normal splicing: Five predict the variant abolishes the canonical 3' splice acceptor site. However, these predictions have yet to be confirmed by functional studies. The variant was absent in 249820 control chromosomes. c.9257-2A>G has been reported in the literature in individuals affected with Hereditary Breast And Ovarian Cancer Syndrome as well as prostate cancer (example, Rebbeck_2018, Nyberg_2020). These data indicate that the variant is likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Four clinical diagnostic laboratories and an expert panel (CIMBA) have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All submitters classified the variant as pathogenic (n=3)/likely pathogenic (n=2). Based on the evidence outlined above, the variant was classified as pathogenic. -
Uncertain significance, criteria provided, single submitter	curation	German Consortium for Hereditary Breast and Ovarian Cancer, University Hospital Cologne	May 13, 2024	Eigene RNA-Analysen?; According to the ClinGen ENIGMA BRCA2 v1.0.0 criteria we chose these criteria: PVS1 (supporting pathogenic): Enigma figure 6 list C, PM2 (supporting pathogenic): not in GnomAD (v3.1.2 non-cancer) -

Hereditary cancer-predisposing syndrome Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Feb 18, 2022	This variant causes an A to G nucleotide substitution at the -2 position of intron 24 of the BRCA2 gene. Splice site prediction tools predict that this variant may have a significant impact on RNA splicing. Although this prediction has not been confirmed in published RNA studies, this variant is expected to result in an absent or disrupted protein product. This variant has not been reported in individuals affected with hereditary cancer in the literature, but has been identified in in 3 families among the CIMBA participants (PMID: 29446198). This variant has not been identified 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	clinical testing	Ambry Genetics	May 24, 2022	The c.9257-2A>G intronic variant results from an A to G substitution two nucleotides upstream from coding exon 24 in the BRCA2 gene. This nucleotide position is highly conserved in available vertebrate species. This alteration was identified in a large, worldwide study of BRCA1/2 mutation positive families (Rebbeck TR et al. Hum Mutat. 2018 05;39:593-620). 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; however, direct evidence is insufficient at this time (Ambry internal data). 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, 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

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Oct 03, 2019

Canonical splice site variant in a gene for which loss-of-function is a known mechanism of disease; Not observed in large population cohorts (Lek 2016); This variant is considered pathogenic by an expert panel (CIMBA); Also known as BRCA2 9485-2A>G; This variant is associated with the following publications: (PMID: 31589614, 31131967) -

Familial cancer of breast Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Baylor Genetics

Jun 29, 2022

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.17	D
BayesDel_noAF	Uncertain	0.0
CADD	Pathogenic	34
DANN	Uncertain	0.99
Eigen	Pathogenic	0.97
Eigen_PC	Pathogenic	0.80
FATHMM_MKL	Pathogenic	0.97	D
GERP RS		5.9

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.90
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.95		Position offset: 29
DS_AL_spliceai		1.0		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: rs886040954; hg19: chr13-32968824;