rs1060502376
Variant summary
Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PVS1_ModeratePM2
The NM_000059.4(BRCA2):c.68-1G>A variant causes a splice acceptor 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 Uncertain significance (★★).
Frequency
Genomes: not found (cov: 33)
Consequence
BRCA2
NM_000059.4 splice_acceptor
NM_000059.4 splice_acceptor
Scores
5
1
1
Splicing: ADA: 1.000
2
Clinical Significance
Conservation
PhyloP100: 7.06
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]
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ACMG classification
Classification made for transcript
Verdict is Uncertain_significance. Variant got 4 ACMG points.
PVS1
Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.02417861 fraction of the gene. Cryptic splice site detected, with MaxEntScore 8.3, offset of 6, new splice context is: ttttttttaaataaatttAGgac. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
PM2
Very rare variant in population databases, with high coverage;
Transcripts
RefSeq
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | Protein | UniProt |
|---|---|---|---|---|---|---|---|---|
| BRCA2 | NM_000059.4 | c.68-1G>A | splice_acceptor_variant | ENST00000380152.8 | NP_000050.3 |
Ensembl
| Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Protein | Appris | UniProt |
|---|---|---|---|---|---|---|---|---|---|---|
| BRCA2 | ENST00000380152.8 | c.68-1G>A | splice_acceptor_variant | 5 | NM_000059.4 | ENSP00000369497 | A2 |
Frequencies
GnomAD3 genomes
GnomAD3 genomes
Cov.:
33
GnomAD4 exome Cov.: 32
GnomAD4 exome
Cov.:
32
GnomAD4 genome
GnomAD4 genome
Cov.:
33
ClinVar
Significance: Uncertain significance
Submissions summary: Uncertain:4
Revision: criteria provided, multiple submitters, no conflicts
LINK: link
Submissions by phenotype
Hereditary cancer-predisposing syndrome Uncertain:2
| Uncertain significance, criteria provided, single submitter | clinical testing | Ambry Genetics | Oct 25, 2021 | The c.68-1G>A intronic variant results from a G to A substitution one nucleotide upstream from coding exon 2 of 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 acceptor site and will result in the creation or strengthening of a novel splice acceptor site. RNA studies have demonstrated that this alteration results in substantial expression of multiple abnormal transcripts including a splice variant which is predicted to result in an in-frame loss of two amino acids as well as one that results in skipping of coding exon 2 (also known as exon 3 in the literature; (Ambry internal data; Nix P et al. Fam Cancer, 2021 Jan; personal communication). The loss of coding exon 2 of is strongly associated with hereditary breast and ovarian cancer phenotype based on multifactorial analysis (Caputo SM et al. Oncotarget, 2018 Apr;9:17334-17348); however the functional and clinical impact of the small in-frame loss is unknown. Functional studies showed that a close-match alteration with a similar splicing profile as this variant, BRCA2 c.68-2A>G, was able to rescue the growth defect in BRCA2-null mouse embryonic stem cells and that these surviving cells maintained partial activity in a homology directed DNA repair functional assay (personal communication). BRCA2 c.68-2A>G is also identified in patients who collectively have a phenotype that is not consistent with a high risk BRCA2 pathogenic variant (Nix P et al. Fam Cancer, 2021 Jan). Since supporting evidence is conflicting at this time, the clinical significance of this alteration remains unclear. It cannot yet be ruled out that this variant may be hypomorphic and present with reduced risks and/or biallelic phenotype. - |
| Uncertain significance, criteria provided, single submitter | clinical testing | Color Diagnostics, LLC DBA Color Health | Jan 11, 2022 | This variant is located in intron 2 of the BRCA2 gene. It is predicted to abolish the intron 2 splice acceptor site at the AG dinucleotide at the 3' terminus of the intron. However, there is an alternative AG dinucleotide at c.72_73, which if used is predicted to cause a 6-basepair deletion (r.68_73del) and an in-frame deletion of 2 amino acids. RNA studies on this and a similar canonical splice acceptor site variant, c.68-2A>G, reported aberrant splicing with the major product being the predicted in-frame deletion of the first six 6 nucleotides in exon 3 (PMID: 32641407, 33469799). This variant has not been reported in individuals affected with hereditary cancer in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. - |
Breast-ovarian cancer, familial, susceptibility to, 2 Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | All of Us Research Program, National Institutes of Health | May 31, 2023 | - - |
Hereditary breast ovarian cancer syndrome Uncertain:1
| Uncertain significance, criteria provided, single submitter | clinical testing | Labcorp Genetics (formerly Invitae), Labcorp | Jan 11, 2022 | This sequence change affects an acceptor splice site in intron 2 of the BRCA2 gene. RNA analysis indicates that disruption of this splice site induces altered splicing and likely results in the loss of 2 amino acid residue(s), but is expected to preserve the integrity of the reading-frame. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with BRCA2-related conditions. ClinVar contains an entry for this variant (Variation ID: 481036). Studies have shown that disruption of this splice site results in the activation of a cryptic splice site in exon 3 (PMID: 32641407). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. - |
Computational scores
Source:
Name
Calibrated prediction
Score
Prediction
BayesDel_addAF
Pathogenic
D
BayesDel_noAF
Pathogenic
CADD
Pathogenic
DANN
Uncertain
Eigen
Pathogenic
Eigen_PC
Pathogenic
FATHMM_MKL
Pathogenic
D
MutationTaster
Benign
D;D
GERP RS
Splicing
Name
Calibrated prediction
Score
Prediction
dbscSNV1_ADA
Pathogenic
dbscSNV1_RF
Pathogenic
SpliceAI score (max)
Details are displayed if max score is > 0.2
DS_AG_spliceai
Position offset: 7
DS_AL_spliceai
Position offset: 1
Find out detailed SpliceAI scores and Pangolin per-transcript scores at