rs81002797

Positions:

• chr13-32326151-G-A
• chr13-32326151-G-C
• chr13-32326151-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.475+1G>A variant causes a splice donor, intron change. The variant was absent in control chromosomes in GnomAD project. 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 Pathogenic (★★★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: BRCA2 NM_000059.4 splice_donor, intron
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Pathogenic reviewed by expert panel P:10
• Conservation: PhyloP100: 4.85

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 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 13-32326151-G-A is Pathogenic according to our data. Variant chr13-32326151-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 51708.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr13-32326151-G-A is described in Lovd as [Pathogenic]. Variant chr13-32326151-G-A is described in Lovd as [Likely_pathogenic]. Variant chr13-32326151-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.475+1G>A		splice_donor_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.475+1G>A		splice_donor_variant, intron_variant		5	NM_000059.4	ENSP00000369497.3
BRCA2	ENST00000530893.7	c.106+1G>A		splice_donor_variant, intron_variant		1		ENSP00000499438.2
BRCA2	ENST00000614259.2	n.475+1G>A		splice_donor_variant, intron_variant		2		ENSP00000506251.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:10

Revision: reviewed by expert panel

Submissions by phenotype

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

Pathogenic, reviewed by expert panel	curation	Evidence-based Network for the Interpretation of Germline Mutant Alleles (ENIGMA)	Apr 03, 2016	Allele-specific assay on patient-derived mRNA demonstrated that the variant allele produces only predicted non-functional transcripts. Variant allele produces r.426_475del transcript (encoding predicted non-functional protein). -
Pathogenic, criteria provided, single submitter	clinical testing	Mendelics	May 28, 2019	- -
Pathogenic, no assertion criteria provided	clinical testing	Breast Cancer Information Core (BIC) (BRCA2)	May 29, 2002	- -
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:2

Pathogenic, criteria provided, single submitter	clinical testing	Clinical Genetics Laboratory, Skane University Hospital Lund	Oct 24, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	Center for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital	Feb 06, 2024	- -

Hereditary breast ovarian cancer syndrome Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jun 16, 2023	This variant is not present in population databases (gnomAD no frequency). For these reasons, this variant has been classified as Pathogenic. Studies have shown that disruption of this splice site results in exon 5 skipping and introduces a premature termination codon (PMID: 23451180). The resulting mRNA is expected to undergo nonsense-mediated decay. ClinVar contains an entry for this variant (Variation ID: 51708). Disruption of this splice site has been observed in individual(s) with Fanconi Anemia and a personal and/or family history of breast and ovarian cancer (PMID: 28102861, 29176636, 29446198, 30792206). This sequence change affects a donor splice site in intron 5 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. -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Oct 17, 2019	Variant summary: BRCA2 c.475+1G>A 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: Four predict that the variant abolishes a 5 prime splicing donor site. At least one publication reports experimental evidence that this variant affects mRNA splicing (Colombo_2012). The variant was absent in 251000 control chromosomes (gnomAD). c.475+1G>A has been reported in the literature in individuals affected with Hereditary Breast and Ovarian Cancer (e.g. Colombo_2012, Nakamura_2013, Arai_2018, Rebbeck_2018). These data indicate that the variant is likely to be associated with disease. The variant has also been detected along with a second BRCA2 mutation in trans in individuals affected with Fanconi anemia (e.g. Mori_2019). Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar (evaluation after 2014) and cited the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Gastric cancer Pathogenic:1

Pathogenic, no assertion criteria provided

research

Laboratory for Genotyping Development, RIKEN

Jul 01, 2021

- -

Hereditary cancer-predisposing syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Jan 25, 2019

The c.475+1G>A intronic pathogenic mutation results from a G to A substitution one nucleotide after coding exon 4 of the BRCA2 gene. This alteration was identified in a large, worldwide study of BRCA1/2 mutation positive families (Rebbeck TR et al. Hum. Mutat., 2018 May;39:593-620). Using the BDGP and ESEfinder splice site prediction tools, this alteration is predicted to abolish the native splice donor site. Further, experimental observation of the effect of this alteration, designated as IVS5+1G>A, on mRNA splicing found it lead to skipping of exon 5, leading to protein truncation (Colombo M et al. PLoS ONE, 2013 Feb;8:e57173). 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.34	D
BayesDel_noAF	Pathogenic	0.25
CADD	Pathogenic	29
DANN	Uncertain	0.99
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.82
FATHMM_MKL	Uncertain	0.97	D
GERP RS		4.9

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
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: rs81002797; hg19: chr13-32900288;