17-43067611-T-C

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM1 PM2 PM5 PP3

The NM_007294.4(BRCA1):c.5071A>G(p.Thr1691Ala) variant causes a missense change. The variant allele was found at a frequency of 0.00000206 in 1,456,898 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic 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. T1691P) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 30)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: BRCA1 NM_007294.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7 B:1 O:1
• Conservation: PhyloP100: 4.79

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 Likely_pathogenic. Variant got 7 ACMG points.

• PM1: In a hotspot region, there are 11 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 7 benign, 17 uncertain in NM_007294.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr17-43067610-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 37628.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.835

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BRCA1	NM_007294.4	c.5071A>G	p.Thr1691Ala	missense_variant	16/23	ENST00000357654.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BRCA1	ENST00000357654.9	c.5071A>G	p.Thr1691Ala	missense_variant	16/23	1	NM_007294.4	P4

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD4 exome AF: 0.00000206 AC: 3 AN: 1456898 Hom.: 0 Cov.: 30 AF XY: 0.00000276 AC XY: 2 AN XY: 725038

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: 0.00000271

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 30

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:7 Benign:1 Other:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Breast-ovarian cancer, familial, susceptibility to, 1 Uncertain:2 Other:1

not provided, no classification provided	in vitro	Brotman Baty Institute, University of Washington	-	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Mar 23, 2017	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 17, 2023	- -

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Feb 04, 2016	This variant is denoted BRCA1 c.5071A>G at the cDNA level, p.Thr1691Ala (T1691A) at the protein level, and results in the change of a Threonine to an Alanine (ACA>GCA). This variant, also known as BRCA1 5190A>G using alternate nomenclature, was reported to be associated with RNA similar to wild type in a study of splicing defects using stimulated lymphocytes (Houdayer 2012). BRCA1 Thr1691Ala was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, suggesting it is not a common benign variant in these populations. Since Threonine and Alanine differ in polarity, charge, size or other properties, this is considered a non-conservative amino acid substitution. BRCA1 Thr1691Ala occurs at a position that is conserved in mammals and is located within the BRCT1 domain (UniProt). In silico analyses predict that this variant is probably damaging to protein structure and function. Based on currently available information, it is unclear whether BRCA1 Thr1691Ala is pathogenic or benign. We consider it to be a variant of uncertain significance. -
Uncertain significance, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jul 12, 2016	Variant summary: The BRCA1 c.5071A>G (p.Thr1691Ala) variant involves the alteration of a conserved nucleotide located in BRCT domain. p.Thr1691Ala was predicted to destabilize the BRCT domain and could have a functional impact (Caputo_2012). 3/4 in silico tools predict a damaging outcome for this variant (SNPs&GO not captured due to low reliability index). 3/5 splice prediction tools predict no significant impact on normal splicing, which was confirmed by RNA analysis in patient's T lymphoctes (Houdayer_2012). This variant is absent in 121146 control chromosomes. This variant has been reported in patients in literature or databases without convincing evidence supporting pathogenicity of this variant. Taken together, this variant is classified as VUS until more information is available. -

Hereditary cancer-predisposing syndrome Uncertain:1 Benign:1

Likely benign, criteria provided, single submitter	clinical testing	Ambry Genetics	Mar 31, 2020	This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -
Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Nov 03, 2022	This missense variant replaces threonine with alanine at codon 1691 of the BRCA1 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). Functional studies have reported that this variant does not impact BRCA1 function in homology-directed repair, subcellular localization and phosphopeptide binding assays (PMID: 30257991) and the variant retains intermediate activity in a haploid cell proliferation assay (PMID: 30209399). This variant has been reported in an individual affected with ovarian cancer (PMID 24504028). 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. -

Familial cancer of breast Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

MGZ Medical Genetics Center

Feb 09, 2024

ACMG codes applied following ENIGMA VCEP rules: PM2_SUP -

Hereditary breast ovarian cancer syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Apr 01, 2023

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. Experimental studies are conflicting or provide insufficient evidence to determine the effect of this variant on BRCA1 function (PMID: 30209399, 30257991, 32546644). Advanced modeling performed at Invitae incorporating data from internal and/or published experimental studies (PMID: 30209399) indicates that this missense variant is expected to disrupt BRCA1 function. ClinVar contains an entry for this variant (Variation ID: 55371). This missense change has been observed in individual(s) with breast and/or ovarian cancer (PMID: 24504028, 34597585). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces threonine, which is neutral and polar, with alanine, which is neutral and non-polar, at codon 1691 of the BRCA1 protein (p.Thr1691Ala). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.44
BayesDel_addAF	Pathogenic	0.25	D
BayesDel_noAF	Uncertain	0.12
Cadd	Benign	23
Dann	Uncertain	1.0
Eigen	Uncertain	0.54
Eigen_PC	Uncertain	0.54
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Benign	0.73	T;T;T;T;T;T;T;T;T;T
M_CAP	Pathogenic	0.70	D
MetaRNN	Pathogenic	0.83	D;D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.40	D
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D;D;D;D;D;D
PrimateAI	Uncertain	0.70	T
PROVEAN	Uncertain	-4.0	D;N;.;D;.;N;D;D;N;D
REVEL	Pathogenic	0.75
Sift	Benign	0.040	D;D;.;D;.;D;D;D;D;D
Sift4G	Uncertain	0.010	D;D;D;D;D;D;D;.;.;D
Polyphen		0.70, 1.0	.;P;.;.;.;.;.;.;D;.
Vest4		0.78
MVP		0.94
MPC		0.080
ClinPred		0.92	D
GERP RS		5.2
Varity_R		0.88
gMVP		0.69

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.070		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: rs397509219; hg19: chr17-41219628;