NM_007294.4:c.4997dupA

Variant names:

• chr17-43067684-G-GT
• rs876658947
• NM_007294.4:c.4997dupA

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_007294.4(BRCA1):​c.4997dupA​(p.Tyr1666fs) variant causes a frameshift, stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,459,710 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★★). Synonymous variant affecting the same amino acid position (i.e. Y1666Y) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 30)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: BRCA1 NM_007294.4 frameshift, stop_gained
• Clinical Significance: Pathogenic reviewed by expert panel P:8
• Conservation: PhyloP100: 3.27
• Publications: 8 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 18 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
• PP5: Variant 17-43067684-G-GT is Pathogenic according to our data. Variant chr17-43067684-G-GT is described in ClinVar as Pathogenic. ClinVar VariationId is 231083.Status of the report is reviewed_by_expert_panel, 3 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BRCA1	NM_007294.4	c.4997dupA	p.Tyr1666fs	frameshift_variant, stop_gained	Exon 16 of 23	ENST00000357654.9	NP_009225.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
BRCA1	ENST00000357654.9	c.4997dupA	p.Tyr1666fs	frameshift_variant, stop_gained	Exon 16 of 23	1	NM_007294.4	ENSP00000350283.3

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1459710 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 726378

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33428

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39682

South Asian (SAS) AF: 0.00 AC: 0 AN: 86204

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53402

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5760

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1110062

Other (OTH) AF: 0.00 AC: 0 AN: 60320

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 30

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:8

Revision: reviewed by expert panel

Submissions by phenotype

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

Dec 15, 2017

Evidence-based Network for the Interpretation of Germline Mutant Alleles (ENIGMA)

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: curation

Variant allele predicted to encode a truncated non-functional protein. -

-

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

The p.Tyr1666X variant has not been previously identified in the literature. This variant is predicted to cause a frameshift, which alters the protein's amino acid sequence leading to a premature stop codon at codon 1666 of BRCA1. This alteration is predicted to lead to a truncated or absent protein and loss of function. Loss of function of the BRCA1 gene is an established disease mechanism in hereditary breast cancer patients. In summary, based on the above information, this variant is classified as pathogenic. -

Nov 25, 2022

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Hereditary breast ovarian cancer syndrome Pathogenic:3

Dec 18, 2023

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.4997dupA (p.Tyr1666X) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Variants downstream of this position have been classified as pathogenic by our laboratory. The variant was absent in 251340 control chromosomes (gnomAD). c.4997dupA has been reported in the literature in individuals affected with Hereditary Breast And Ovarian Cancer Syndrome (example: Thuan Tran_2022). The following publication has been ascertained in the context of this evaluation (PMID: 35070997). Four submitters (including ENIGMA expert panel) have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Apr 22, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Tyr1666*) in the BRCA1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in BRCA1 are known to be pathogenic (PMID: 20104584). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with BRCA1-related conditions. ClinVar contains an entry for this variant (Variation ID: 231083). For these reasons, this variant has been classified as Pathogenic. -

Nov 11, 2022

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Tyr1666X variant in BRCA1 has been reported in at least 3 individuals with BRCA1-associated cancers, and segregated with disease in at least 2 affected relatives from one family (Van Thuan 2020 PMID: 32009791, Le 2022 PMID: 35205313). It was absent from large population studies. This nonsense variant is a result of a duplication of one base pair at position 4997 (c.4997dupA), which creates a premature termination codon at position 1666. This alteration is then predicted to lead to a truncated or absent protein. Heterozygous loss of function of the BRCA1 gene is an established disease mechanism in autosomal dominant hereditary breast and ovarian cancer (HBOC). Additionally, this variant was classified as pathogenic on December 15, 2017 by the ClinGen-approved ENIGMA expert panel (Variation ID 231083). In summary, this variant meets criteria to be classified as pathogenic for autosomal dominant HBOC. ACMG/AMP Criteria applied: PM2_Supporting, PVS1, PS4_Supporting. -

not provided Pathogenic:1

Jun 09, 2016

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This pathogenic variant is denoted BRCA1 c.4997dupA at the cDNA level and p.Tyr1666Ter (Y1666X) at the protein level. Using alternate nomenclature this variant would be defined as BRCA1 5116dupA. The substitution creates a nonsense variant, which changes a Tyrosine to a premature stop codon (TAC>TAA), and is predicted to cause loss of normal protein function through either protein truncation or nonsense-mediated mRNA decay. Although this variant has not, to our knowledge, been reported in the literature, the adjacent variant BRCA1 c.4998C>A, which also results in a premature stop codon at this residue (p.Tyr1666Ter), has been reported in an individual with breast cancer (Lecarpentier 2012). We therefore consider BRCA1 c.4997dupA to be pathogenic. -

Hereditary cancer-predisposing syndrome Pathogenic:1

Aug 31, 2022

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.4997dupA pathogenic mutation, located in coding exon 15 of the BRCA1 gene, results from a duplication of A at nucleotide position 4997, causing a translational frameshift with a predicted alternate stop codon. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		3.3
Mutation Taster		=0/200	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.090		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs876658947; hg19: chr17-41219701;