13-32316528-G-C

Variant summary

Our verdict is Pathogenic. Variant got 22 ACMG points: 22P and 0B. PVS1 PM2 PP3_Strong PP5_Very_Strong

The NM_000059.4(BRCA2):c.67+1G>C variant causes a splice donor change. The variant allele was found at a frequency of 0.000000685 in 1,460,826 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: 6.8e-7 (0 hom.)
• Consequence: BRCA2 NM_000059.4 splice_donor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 5.43

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 22 ACMG points.

• PVS1: Splicing 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
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 13-32316528-G-C is Pathogenic according to our data. Variant chr13-32316528-G-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 224450.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr13-32316528-G-C is described in Lovd as [Pathogenic]. Variant chr13-32316528-G-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BRCA2	NM_000059.4	c.67+1G>C		splice_donor_variant		ENST00000380152.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BRCA2	ENST00000380152.8	c.67+1G>C		splice_donor_variant		5	NM_000059.4	A2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460826 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 726776

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: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

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

Likely pathogenic, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Mar 04, 2016	- -
Pathogenic, criteria provided, single submitter	clinical testing	Genetics and Molecular Pathology, SA Pathology	Nov 09, 2020	- -

Breast neoplasm Pathogenic:1

Pathogenic, criteria provided, single submitter

research

Laboratory of Molecular Diagnosis of Cancer, West China Hospital, Sichuan University

Nov 01, 2015

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Genetic Services Laboratory, University of Chicago

Mar 09, 2020

- -

Hereditary cancer-predisposing syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 25, 2022

The c.67+1G>C intronic pathogenic mutation results from a G to C substitution one nucleotide after coding exon 1 of the BRCA2 gene. This alteration has been detected in 1/507 unselected Chinese breast cancer patients (Zhong X et al. PLoS ONE 2016 Jun;11:e0156789). Additionally, two other disease-causing mutations at the same position, c.67+1G>A and c.67+1G>T, have been identified in families with HBOC (Meyer P et al. Hum. Mutat. 2003 Sep;22:259; Sagi M et al. Fam. Cancer. 2011 Mar;10(1):59-63) and functional studies have shown that both of these alterations result in skipping of exon 2 (Bonatti F et al. Cancer Genet Cytogenet. 2006 Oct 15;170(2):93-101; Houdayer C et al. Hum. Mutat. 2012 Aug;33:1228-38). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). In silico splice site analysis predicts that this alteration will weaken the native splice donor site. RNA studies have demonstrated that this alteration results in abnormal splicing in the set of samples tested (Ambry internal data). In addition to the clinical data presented in the literature, 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 a disease-causing mutation. -

Hereditary breast ovarian cancer syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Dec 23, 2020

For these reasons, this variant has been classified as Pathogenic. Studies have shown that disruption of this splice site disrupts mRNA splicing and is expected to lead to the loss of protein expression (PMID: 17011979). Disruption of this splice site has been observed in individual(s) with breast cancer (PMID: 27257965, 30702160, 21063910). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 224450). This variant is not present in population databases (ExAC no frequency). This sequence change affects a donor splice site in intron 2 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	0.30	D
BayesDel_noAF	Pathogenic	0.20
Cadd	Pathogenic	32
Dann	Uncertain	0.99
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.89
FATHMM_MKL	Uncertain	0.90	D
MutationTaster	Benign	1.0	D;D
GERP RS		5.1

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.95
SpliceAI score (max)		0.98		Details are displayed if max score is > 0.2
DS_DL_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: rs81002796; hg19: chr13-32890665;