NM_007294.4:c.81-1G>A

Variant names:

• chr17-43115780-C-T
• rs80358018
• NM_007294.4:c.81-1G>A

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1_Moderate PM2 PP5_Very_Strong

The NM_007294.4(BRCA1):​c.81-1G>A variant causes a splice acceptor, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,012 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 Pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: BRCA1 NM_007294.4 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:12
• Conservation: PhyloP100: 3.48
• Publications: 22 publications found

Genes affected

BRCA1 (HGNC:1100): (BRCA1 DNA repair associated) This gene encodes a 190 kD nuclear phosphoprotein that plays a role in maintaining genomic stability, and it also acts as a tumor suppressor. The BRCA1 gene contains 22 exons spanning about 110 kb of DNA. The encoded protein combines with other tumor suppressors, DNA damage sensors, and signal transducers to form a large multi-subunit protein complex known as the BRCA1-associated genome surveillance complex (BASC). This gene product associates with RNA polymerase II, and through the C-terminal domain, also interacts with histone deacetylase complexes. This protein thus plays a role in transcription, DNA repair of double-stranded breaks, and recombination. Mutations in this gene are responsible for approximately 40% of inherited breast cancers and more than 80% of inherited breast and ovarian cancers. Alternative splicing plays a role in modulating the subcellular localization and physiological function of this gene. Many alternatively spliced transcript variants, some of which are disease-associated mutations, have been described for this gene, but the full-length natures of only some of these variants has been described. A related pseudogene, which is also located on chromosome 17, has been identified. [provided by RefSeq, May 2020]

BRCA1 Gene-Disease associations (from GenCC):

• breast-ovarian cancer, familial, susceptibility to, 1

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, ClinGen, Labcorp Genetics (formerly Invitae), Genomics England PanelApp
• Fanconi anemia, complementation group S

  Inheritance: AR Classification: DEFINITIVE, STRONG, MODERATE, LIMITED Submitted by: G2P, Labcorp Genetics (formerly Invitae), ClinGen, Ambry Genetics
• pancreatic cancer, susceptibility to, 4

  Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
• hereditary breast ovarian cancer syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Fanconi anemia

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.009656653 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 17-43115780-C-T is Pathogenic according to our data. Variant chr17-43115780-C-T is described in ClinVar as Pathogenic. ClinVar VariationId is 91668.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BRCA1	NM_007294.4	c.81-1G>A		splice_acceptor_variant, intron_variant	Intron 2 of 22	ENST00000357654.9	NP_009225.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
BRCA1	ENST00000357654.9	c.81-1G>A		splice_acceptor_variant, intron_variant	Intron 2 of 22	1	NM_007294.4	ENSP00000350283.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000400 AC: 1 AN: 250180 AF XY: 0.00000739

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000884

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461012 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 726802

African (AFR) AF: 0.00 AC: 0 AN: 33468

American (AMR) AF: 0.00 AC: 0 AN: 44634

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26098

East Asian (EAS) AF: 0.00 AC: 0 AN: 39664

South Asian (SAS) AF: 0.00 AC: 0 AN: 86132

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53370

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 9.00e-7 AC: 1 AN: 1111534

Other (OTH) AF: 0.00 AC: 0 AN: 60344

GnomAD4 genome Cov.: 32

Alfa AF: 0.00000531 Hom.: 0

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.00

EpiControl AF: 0.0000594

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:12

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Breast-ovarian cancer, familial, susceptibility to, 1 Pathogenic:5

Oct 02, 2015

Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA), c/o University of Cambridge

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Feb 20, 2004

Breast Cancer Information Core (BIC) (BRCA1)

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Mar 02, 2020

BRCAlab, Lund University

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Aug 12, 2010

Sharing Clinical Reports Project (SCRP)

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Nov 16, 2023

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Pathogenic:2

Dec 24, 2018

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The variant disrupts a canonical splice site, and is therefore predicted to result in the loss of a functional protein. Found in at least one symptomatic patient, and found in general population data that is consistent with pathogenicity. -

Dec 09, 2023

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Canonical splice site variant predicted to result in a null allele in a gene for which loss-of-function is a known mechanism of disease; Published functional studies demonstrate a damaging effect: variant classified as non-functional based on a saturation genome editing (SGE) assay measuring cell survival (PMID: 30209399); Observed in individuals with a personal or family history consistent with pathogenic variants in this gene (PMID: 10644434, 22711857, 29446198); Not observed at significant frequency in large population cohorts (gnomAD); Also known as 200-1G>A; This variant is associated with the following publications: (PMID: 25525159, 10644434, 29922827, 22711857, 29446198, 30078507, 30720243, 30787465, 36123164, 36243179, 30209399) -

Hereditary cancer-predisposing syndrome Pathogenic:2

May 09, 2022

Color Diagnostics, LLC DBA Color Health

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant causes a G to A nucleotide substitution at the -1 position of intron 2 splice acceptor site of the BRCA1 gene. This variant is also known as 200-1G>A and IVS2-1G>A in the literature. Splice site prediction tools suggest that this variant may have a significant impact on RNA splicing. A similar variant c.81-1G>C has been shown in RNA studies to impact the splicing of exon 3 that partially encodes the RING domain, which is important for BRCA1 function and is noted to have clinically relevant mutations (PMID: 22505045, 22737296, 23239986). This variant also has been reported to cause loss of BRCA1 function in haploid cell proliferation assays (PMID: 30209399, 31467430). This variant has been detected in at least three individuals and one family affected with ovarian cancer and breast cancer (PMID: 10644434, 22711857, 30287823). Three other similar variants at the -1 and -2 positions of this intron have been reported in at least 5 individuals affected with breast and ovarian cancer (PMID: 30078507, 32438681, 33461583, 33850850). This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Loss of BRCA1 function is a known mechanism of disease (clinicalgenome.org). Based on the available evidence, this variant is classified as Pathogenic. -

Jul 17, 2024

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.81-1G>A intronic pathogenic mutation results from a G to A substitution one nucleotide upstream from coding exon 2 of the BRCA1 gene. This nucleotide position is highly conserved in available vertebrate species. This mutation has been previously identified in multiple breast and/or ovarian cancer cohorts (Kroiss R et al. Hum Mutat. 2005 Dec;26(6):583-9; Alsop K et al. J Clin Oncol. 2012 Jul 20;30(21):2654-63). Of note, this alteration is also designated as IVS2-1G>A in published literature. 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 abnormal splicing in the set of samples tested (Ambry internal data). One functional study found that this nucleotide substitution is non-functional in a high throughput genome editing haploid cell survival assay (Findlay GM et al. Nature. 2018 Oct;562(7726):217-222). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). Based on the supporting evidence, this variant is interpreted as a disease-causing mutation. -

Hereditary breast ovarian cancer syndrome Pathogenic:2

Apr 18, 2022

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: BRCA1 c.81-1G>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 the variant abolishes a 3' acceptor site. The variant allele was found at a frequency of 4e-06 in 250180 control chromosomes (gnomAD). c.81-1G>A has been reported in the literature in multiple individuals with personal and/or family history of breast and/or ovarian cancer (e.g. Momozawa_2018, Rebbeck_2018, Li_2018). These data indicate that the variant is very likely to be associated with disease. An in vitro study that assessed the effect of the variant in a haploid human cell line whose survival is dependent on intact BRCA1 function, and demonstrated a damaging effect for this variant (Findlay 2018). Six clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as pathogenic (n=5) / likely pathogenic (n=1). Based on the evidence outlined above, the variant was classified as pathogenic. -

Jan 22, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects an acceptor splice site in intron 2 of the BRCA1 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 BRCA1 are known to be pathogenic (PMID: 20104584). This variant is present in population databases (rs80358018, gnomAD 0.0009%). Disruption of this splice site has been observed in individual(s) with breast cancer and/or ovarian cancer (PMID: 16287141, 22711857). ClinVar contains an entry for this variant (Variation ID: 91668). Studies have shown that disruption of this splice site alters mRNA splicing and is expected to lead to the loss of protein expression (PMID: 22505045). For these reasons, this variant has been classified as Pathogenic. -

Gastric cancer Pathogenic:1

Jul 01, 2021

Laboratory for Genotyping Development, RIKEN

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: research

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.40	D
BayesDel_noAF	Pathogenic	0.34
CADD	Pathogenic	32
DANN	Uncertain	0.99
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.94
FATHMM_MKL	Uncertain	0.89	D
PhyloP100		3.5
GERP RS		6.0
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.53		Position offset: -17
DS_AL_spliceai		0.96		Position offset: -1

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

Other links and lift over

dbSNP: rs80358018; hg19: chr17-41267797;