13-32376796-G-A

Position:

• chr13-32376796-G-A

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM2 PP5_Very_Strong

The NM_000059.4(BRCA2):​c.8754+5G>A variant causes a splice donor 5th base, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,650 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign 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: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: BRCA2 NM_000059.4 splice_donor_5th_base, intron
• Scores: Splicing: ADA: 0.9986
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:10 U:1
• Conservation: PhyloP100: 2.49

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 10 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 13-32376796-G-A is Pathogenic according to our data. Variant chr13-32376796-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 38182.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr13-32376796-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BRCA2	NM_000059.4	c.8754+5G>A		splice_donor_5th_base_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.8754+5G>A		splice_donor_5th_base_variant, intron_variant		5	NM_000059.4	ENSP00000369497	A2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461650 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727102

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:10 Uncertain:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Breast-ovarian cancer, familial, susceptibility to, 2 Pathogenic:4 Uncertain:1

Pathogenic, no assertion criteria provided	clinical testing	Sharing Clinical Reports Project (SCRP)	May 01, 2012	- -
Pathogenic, criteria provided, single submitter	clinical testing	Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA), c/o University of Cambridge	Oct 02, 2015	- -
Uncertain significance, no assertion criteria provided	clinical testing	Breast Cancer Information Core (BIC) (BRCA2)	Dec 23, 2003	- -
Pathogenic, no assertion criteria provided	clinical testing	Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Genome Diagnostics Laboratory, University Medical Center Utrecht	Jul 28, 2017	- -

not provided Pathogenic:3

Pathogenic, no assertion criteria provided	clinical testing	Clinical Genetics Laboratory, Department of Pathology, Netherlands Cancer Institute	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC)	-	- -

Hereditary cancer-predisposing syndrome Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Mar 22, 2022	This variant causes a G to A nucleotide substitution at the +5 position of intron 21 of the BRCA2 gene. RNA studies have reported that this variant causes the out-of-frame splicing of intron 21 in RNA from carrier-derived cells, in minigene splicing assay and in mouse embryonic stem cells (PMID: 18693280, 25146914, 25382762). Moreover, this variant failed to complement Brca2-deficient mouse embryonic stem cell (PMID: 25146914). This variant has been reported in an individual affected with breast and/or ovarian cancer (PMID: 18693280). 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 Pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Ambry Genetics	Apr 28, 2022	The c.8754+5G>A intronic variant results from a G to A substitution 5 nucleotides after coding exon 20 in the BRCA2 gene. This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice donor site and will result in the creation or strengthening of a novel splice donor site. This alteration has been reported in a patient diagnosed with early-onset breast cancer who had a family history of breast cancer (Vreeswijk MP et al. Hum Mutat. 2009 Jan;30(1):107-14). Multiple splicing assays have shown this alteration results in an aberrant transcript which retains 46 nucleotides from intron 20 and would cause a translational frameshift with a predicted alternate stop codon (Vreeswijk MP et al. Hum Mutat. 2009 Jan;30(1):107-14; Hendriks G et al. Hum Mutat. 2014 Nov;35(11):1382-91; Acedo A et al. Hum Mutat. 2015 Feb;36(2):210-21). In addition, Hendriks et al. (2014) used a functional complementation assay in mouse-embryonic stem (mES) cells which showed that the alteration could not complement the lethality of mBrca2-deficient mES cells. This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Hereditary breast ovarian cancer syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 31, 2021

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. Nucleotide substitutions within the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this variant is associated with retention of 46 nucleotides from intron 21, which introduces a premature termination codon (PMID: 18693280, 25146914). The resulting mRNA is expected to undergo nonsense-mediated decay. Studies have shown that this variant alters BRCA2 gene expression (PMID: 25146914). This variant has been observed in individual(s) with clinical features of hereditary breast and ovarian cancer (HBOC) syndrome (PMID: 18693280). This variant is also known as IVS21+5G>A. ClinVar contains an entry for this variant (Variation ID: 38182). This variant is not present in population databases (ExAC no frequency). This sequence change falls in intron 21 of the BRCA2 gene. It does not directly change the encoded amino acid sequence of the BRCA2 protein. RNA analysis indicates that this variant 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_noAF	Benign	-0.27
CADD	Benign	22
DANN	Benign	0.95

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.97
SpliceAI score (max)		0.85		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.76		Position offset: 41
DS_DL_spliceai		0.85		Position offset: -5

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

Publications

LitVar

Other links and lift over

dbSNP: rs81002813; hg19: chr13-32950933;