Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2BP4
The NM_007294.4(BRCA1):c.527C>T(p.Thr176Met) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,458,456 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. T176T) has been classified as Likely benign.
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]
Uncertain significance, criteria provided, single submitter
clinical testing
Ambry Genetics
Jan 25, 2023
The p.T176M variant (also known as c.527C>T), located in coding exon 6 of the BRCA1 gene, results from a C to T substitution at nucleotide position 527. The threonine at codon 176 is replaced by methionine, an amino acid with similar properties. This alteration (designated as 646C>T) was detected in an individual with contralateral breast cancer (Pellegrino B et al. Acta Biomed, 2016 05;87:54-63). This amino acid position is poorly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -
Uncertain significance, criteria provided, single submitter
clinical testing
Color Diagnostics, LLC DBA Color Health
Apr 18, 2022
This missense variant replaces threonine with methionine at codon 176 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 detected in an individual affected with contralateral breast cancer (PMID: 27163896). This variant has been identified in 2/251452 chromosomes 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
curation
Sema4, Sema4
May 21, 2021
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not provided Uncertain:2
Uncertain significance, criteria provided, single submitter
clinical testing
GeneDx
May 31, 2023
Observed in an individual with bilateral breast cancer (Pellegrino et al., 2016); In silico analysis, which includes protein predictors and evolutionary conservation, supports that this variant does not alter protein structure/function; Not observed at a significant frequency in large population cohorts (gnomAD); Also known as 646C>T; This variant is associated with the following publications: (PMID: 9788437, 20215511, 27163896) -
Uncertain significance, criteria provided, single submitter
clinical testing
Quest Diagnostics Nichols Institute San Juan Capistrano
Oct 07, 2022
The frequency of this variant in the general population, 0.000008 (2/251452 chromosomes, http://gnomad.broadinstitute.org), is uninformative in assessment of its pathogenicity. In the published literature, the variant has been reported in an individual with contralateral breast cancer (PMID: 27163896 (2016). Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded predictions that this variant is benign. Based on the available information, we are unable to determine the clinical significance of this variant. -
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 22, 2023
This missense variant replaces threonine with methionine at codon 176 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 detected in an individual affected with contralateral breast cancer (PMID: 27163896). This variant has been identified in 2/251452 chromosomes 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;C2676676:Breast-ovarian cancer, familial, susceptibility to, 1;C3280442:Pancreatic cancer, susceptibility to, 4;C4554406:Fanconi anemia, complementation group S Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
Fulgent Genetics, Fulgent Genetics
Oct 31, 2018
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Hereditary breast ovarian cancer syndrome Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
Labcorp Genetics (formerly Invitae), Labcorp
Jan 21, 2024
This sequence change replaces threonine, which is neutral and polar, with methionine, which is neutral and non-polar, at codon 176 of the BRCA1 protein (p.Thr176Met). This variant is present in population databases (no rsID available, gnomAD 0.006%). This missense change has been observed in individual(s) with breast and/or ovarian cancer (PMID: 27163896). This variant is also known as 646C>T. ClinVar contains an entry for this variant (Variation ID: 409326). 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. -
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