rs8176139

Positions:

• chr17-43099883-A-C
• chr17-43099883-A-G
• chr17-43099883-A-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_007294.4(BRCA1):​c.442-3T>G variant causes a splice region, splice polypyrimidine tract, intron change. The variant allele was found at a frequency of 0.000000688 in 1,453,086 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: BRCA1 NM_007294.4 splice_region, splice_polypyrimidine_tract, intron
• Scores: Splicing: ADA: 0.9915
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: 3.92

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, max_spliceai. No scorers claiming Uncertain. Scorers claiming Benign: dbscSNV1_RF.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BRCA1	NM_007294.4	c.442-3T>G		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		ENST00000357654.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BRCA1	ENST00000357654.9	c.442-3T>G		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		1	NM_007294.4	P4

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.88e-7 AC: 1 AN: 1453086 Hom.: 0 Cov.: 29 AF XY: 0.00 AC XY: 0 AN XY: 723492

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: 9.06e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Dec 08, 2022	This variant causes a T to G nucleotide substitution at the -3 position of intron 6 of the BRCA1 gene. An RNA study has reported that this variant increases the use of a cryptic splice site in exon 7, resulting in an in-frame deletion r.442_444del (p.Gly148del) in carrier cellular RNA (PMID: 22505045). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in an individual affected with early-onset breast cancer (PMID: 29310832). 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	Oct 24, 2023	The c.442-3T>G intronic variant results from a T to G substitution 3 nucleotides upstream from coding exon 6 in the BRCA1 gene. This nucleotide position is highly conserved in available vertebrate species.This alteration was reported in a Greek woman with a personal history of breast cancer diagnosed at age 30 (Apessos A et al. Cancer Genet 2018 Jan;220:1-12). In silico splice site analysis predicts that this alteration will weaken the native splice acceptor site. Canonical splice site variants are typically considered deleterious, however, alterations at this particular splice acceptor site result in a transcript with a predicted in-frame loss of a single amino acid at the beginning of coding exon 6 (Ambry internal data; Houdayer C et al. Hum. Mutat., 2012 Aug;33:1228-38). This single amino acid loss is a naturally occurring isoform and may be referred to as Δ8p in some literature (Colombo M et al. Hum Mol Genet. 2014; 23:3666-80). The functional and clinical significance of this single amino acid loss is unknown. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Breast-ovarian cancer, familial, susceptibility to, 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

All of Us Research Program, National Institutes of Health

Feb 24, 2023

This variant causes a T to G nucleotide substitution at the -3 position of intron 6 of the BRCA1 gene. An RNA study has reported that this variant increases the use of a cryptic splice site in exon 7, resulting in an in-frame deletion r.442_444del (p.Gly148del) in carrier cellular RNA (PMID: 22505045). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in an individual affected with early-onset breast cancer (PMID: 29310832). 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. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Quest Diagnostics Nichols Institute San Juan Capistrano

Apr 16, 2020

- -

Hereditary breast ovarian cancer syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jan 10, 2024

This sequence change falls in intron 6 of the BRCA1 gene. It does not directly change the encoded amino acid sequence of the BRCA1 protein. It affects a nucleotide within the consensus splice site. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with breast cancer (PMID: 29310832). ClinVar contains an entry for this variant (Variation ID: 485396). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.44
CADD	Benign	16
DANN	Benign	0.84

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.99
dbscSNV1_RF	Benign	0.65
SpliceAI score (max)		0.86		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.86		Position offset: -3

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

Publications

LitVar

Other links and lift over

dbSNP: rs8176139; hg19: chr17-41251900;