chr17-43091579-T-C

Position:

• chr17-43091579-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 4P and 1B. PM2 PM5 BP4

The NM_007294.4(BRCA1):​c.3952A>G​(p.Ile1318Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I1318L) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: BRCA1 NM_007294.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7 B:4
• Conservation: PhyloP100: 0.0120

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 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr17-43091579-T-G is described in Lovd as [Likely_pathogenic].
• BP4: Computational evidence support a benign effect (MetaRNN=0.2743758).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BRCA1	NM_007294.4	c.3952A>G	p.Ile1318Val	missense_variant	10/23	ENST00000357654.9	NP_009225.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BRCA1	ENST00000357654.9	c.3952A>G	p.Ile1318Val	missense_variant	10/23	1	NM_007294.4	ENSP00000350283.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:7 Benign:4

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:3 Benign:3

Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics Laboratory, Department of Pathology, Netherlands Cancer Institute	-	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Feb 09, 2021	Not observed in large population cohorts (Lek 2016); In silico analysis supports that this missense variant does not alter protein structure/function; Also known as 4071A>G; Observed in individuals with a family history of breast and/or ovarian cancer (Arnold 1999, Meindl 2002).; This variant is associated with the following publications: (PMID: 10502781, 11802209, 12457999, 28277317) -
Uncertain significance, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Apr 02, 2021	The BRCA1 c.3952A>G; p.Ile1318Val variant (rs397509121) is reported in the literature in at least two individuals affected with hereditary breast/ovarian cancer (Arnold 1999, Meindl 2002). This variant is absent from general population databases (Exome Variant Server, Genome Aggregation Database), indicating it is not a common polymorphism. The isoleucine at codon 1318 is weakly conserved, but computational analyses are uncertain whether this variant is neutral or deleterious (REVEL: 0.54). Due to limited information, the clinical significance of the p.Ile1318Val variant is uncertain at this time. -
Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Jul 29, 2024	- -
Likely benign, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -

Hereditary cancer-predisposing syndrome Uncertain:2 Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	Sep 08, 2022	The p.I1318V variant (also known as c.3952A>G), located in coding exon 9 of the BRCA1 gene, results from an A to G substitution at nucleotide position 3952. The isoleucine at codon 1318 is replaced by valine, an amino acid with highly similar properties. This alteration has been reported in studies of families with hereditary breast and ovarian cancer (Arnold N et al. Hum. Mutat. 1999; 14(4):333-9; Meindl A et al. Int. J. Cancer 2002 Feb; 97(4):472-80). This amino acid position is well conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -
Likely benign, criteria provided, single submitter	curation	University of Washington Department of Laboratory Medicine, University of Washington	Mar 23, 2023	Missense variant in a coldspot region where missense variants are very unlikely to be pathogenic (PMID:31911673). -
Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Sep 05, 2023	This missense variant replaces isoleucine with valine at codon 1318 of the BRCA1 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in at least one suspected hereditary breast and ovarian cancer family (PMID: 10502781, 11802209). 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. -

BRCA1-related disorder Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

Feb 20, 2024

The BRCA1 c.3952A>G variant is predicted to result in the amino acid substitution p.Ile1318Val. This variant was reported in individuals with a personal or family history of breast and/or ovarian cancer (Meindl et al. 2002. PubMed ID: 11802209; Fanale et al. 2021. PubMed ID: 34178674). This variant occurs within a region of the BRCA1 gene that is predicted to be tolerant to missense variation (Table 2, Dines et al. 2020. PubMed ID: 31911673). This variant has not been reported in a large population database (http://gnomad.broadinstitute.org), indicating this variant is rare. This variant is interpreted as uncertain or likely benign in ClinVar (https://www.ncbi.nlm.nih.gov/clinvar/variation/55058/). At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Hereditary breast ovarian cancer syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 17, 2023

This sequence change replaces isoleucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 1318 of the BRCA1 protein (p.Ile1318Val). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with breast and/or ovarian cancer (PMID: 10502781, 12457999, 34178674). ClinVar contains an entry for this variant (Variation ID: 55058). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt BRCA1 protein function with a negative predictive value of 95%. 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
AlphaMissense	Benign	0.084
BayesDel_addAF	Pathogenic	0.21	D
BayesDel_noAF	Uncertain	0.060
CADD	Benign	11
DANN	Benign	0.94
DEOGEN2	Benign	0.082	T;.;.;.
Eigen	Benign	-0.25
Eigen_PC	Benign	-0.23
FATHMM_MKL	Benign	0.067	N
LIST_S2	Benign	0.86	D;D;D;D
M_CAP	Benign	0.017	T
MetaRNN	Benign	0.27	T;T;T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	0.76	N;N;.;.
PrimateAI	Benign	0.30	T
PROVEAN	Benign	-0.10	N;N;N;N
REVEL	Uncertain	0.54
Sift	Benign	0.41	T;T;T;T
Sift4G	Benign	1.0	T;T;T;T
Polyphen		0.0090	B;.;.;B
Vest4		0.56
MutPred		0.56		Loss of methylation at K1322 (P = 0.1052);Loss of methylation at K1322 (P = 0.1052);.;Loss of methylation at K1322 (P = 0.1052);
MVP		0.60
MPC		0.077
ClinPred		0.061	T
GERP RS		3.6
Varity_R		0.024
gMVP		0.052

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs397509121; hg19: chr17-41243596;