17-43074340-G-A

Position:

• chr17-43074340-G-A

Variant summary

Our verdict is Pathogenic. Variant got 20 ACMG points: 20P and 0B. PVS1 PM2 PP3_Moderate PP5_Very_Strong

The NM_007294.4(BRCA1):​c.4666C>T​(p.Gln1556Ter) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★★). Synonymous variant affecting the same amino acid position (i.e. Q1556Q) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 31)
• Consequence: BRCA1 NM_007294.4 stop_gained
• Clinical Significance: Pathogenic reviewed by expert panel P:8
• Conservation: PhyloP100: 2.75

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 Pathogenic. Variant got 20 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 17-43074340-G-A is Pathogenic according to our data. Variant chr17-43074340-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 433717.Status of the report is reviewed_by_expert_panel, 3 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BRCA1	NM_007294.4	c.4666C>T	p.Gln1556Ter	stop_gained	14/23	ENST00000357654.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BRCA1	ENST00000357654.9	c.4666C>T	p.Gln1556Ter	stop_gained	14/23	1	NM_007294.4	P4

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:8

Revision: reviewed by expert panel

Submissions by phenotype

Breast-ovarian cancer, familial, susceptibility to, 1 Pathogenic:3

Pathogenic, reviewed by expert panel	curation	Evidence-based Network for the Interpretation of Germline Mutant Alleles (ENIGMA)	Dec 15, 2017	Variant allele predicted to encode a truncated non-functional protein. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Dec 27, 2022	- -
Pathogenic, no assertion criteria provided	clinical testing	Department of Pathology and Laboratory Medicine, Sinai Health System	-	The p.Gln1556X variant has not been reported in the literature. The variant leads to a premature stop codon at position 1556 which is predicted to cause premature truncation of the protein product. This is a loss of function DNA variant and loss of function is an established disease mechanism for the BRCA1 gene in hereditary breast and ovarian cancer. In summary, based on the above information, this variant is classified as pathogenic. -

Hereditary cancer-predisposing syndrome Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Ambry Genetics	Sep 17, 2021	The p.Q1556* pathogenic mutation (also known as c.4666C>T), located in coding exon 13 of the BRCA1 gene, results from a C to T substitution at nucleotide position 4666. This changes the amino acid from a glutamine to a stop codon within coding exon 13. This variant has been observed in breast and ovarian cancer cohorts (Oros KK et al. Int J Cancer, 2004 Nov;112:411-9; Borg A et al. Hum Mutat, 2010 Mar;31:E1200-40; Lhotova K et al. Cancers (Basel), 2020 Apr;12). In silico splice site analysis predicts that this alteration will weaken the native splice donor site and will result in the creation or strengthening of a novel splice donor site. RNA studies have demonstrated that this alteration results in abnormal splicing in the set of samples tested (Ambry internal data). This alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. As such, this alteration is interpreted as a disease-causing mutation. -
Pathogenic, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Sep 08, 2020	This variant changes 1 nucleotide in exon 14 of the BRCA1 gene, creating a premature translation stop signal. This variant is expected to result in an absent or non-functional protein product. To our knowledge, 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). Loss of BRCA1 function is a known mechanism of disease (clinicalgenome.org). Based on the available evidence, this variant is classified as Pathogenic. -

Breast and/or ovarian cancer Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

CZECANCA consortium

Jun 11, 2019

- -

Inherited breast cancer and ovarian cancer Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Genomics and Molecular Medicine Service, East Genomic Laboratory Hub, NHS Genomic Medicine Service

Jun 04, 2024

PVS1,PM2 -

Hereditary breast ovarian cancer syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 02, 2021

This sequence change creates a premature translational stop signal (p.Gln1556*) in the BRCA1 gene. It is expected to result in an absent or disrupted protein product. This variant is not present in population databases (ExAC no frequency). For these reasons, this variant has been classified as Pathogenic. Loss-of-function variants in BRCA1 are known to be pathogenic (PMID: 20104584). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site, but this prediction has not been confirmed by published transcriptional studies. This variant has not been reported in the literature in individuals with BRCA1-related conditions. ClinVar contains an entry for this variant (Variation ID: 433717). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.40	D
BayesDel_noAF	Pathogenic	0.34
CADD	Pathogenic	49
DANN	Uncertain	1.0
Eigen	Pathogenic	0.77
Eigen_PC	Uncertain	0.54
FATHMM_MKL	Benign	0.50	D
MutationTaster	Benign	1.0	A;A;A;A;A;A;A;A;A;A;D;D;D;D
Vest4		0.87
GERP RS		5.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.87		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.83		Position offset: 2
DS_DL_spliceai		0.87		Position offset: -9

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

Publications

LitVar

Other links and lift over

dbSNP: rs1555581812; hg19: chr17-41226357;