Our verdict is Likely benign. The variant received -1 ACMG points: 2P and 3B. PM2BP4_ModerateBP6
The NM_007294.4(BRCA1):āc.1636A>Gā(p.Met546Val) 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. 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. M546I) 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]
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
Our verdict: Likely_benign. The variant received -1 ACMG points.
PM2
Very rare variant in population databases, with high coverage;
BP4
Computational evidence support a benign effect (MetaRNN=0.22404224).
BP6
Variant 17-43093895-T-C is Benign according to our data. Variant chr17-43093895-T-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 142331.
University of Washington Department of Laboratory Medicine, University of Washington
Significance:Likely benign
Review Status:criteria provided, single submitter
Collection Method:curation
Missense variant in a coldspot region where missense variants are very unlikely to be pathogenic (PMID:31911673).
Aug 16, 2013
Ambry Genetics
Significance:Uncertain significance
Review Status:criteria provided, single submitter
Collection Method:clinical testing
The p.M546V variant (also known as c.1636A>G and 1755A>T) is located in coding exon 9 of the BRCA1 gene. This alteration results from a A to G substitution at nucleotide position 1636. The methionine at codon 546 is replaced by valine, an amino acid with highly similar properties. In one study including 25 Chinese women with hereditary breast and ovarian cancer, this alteration was identified in one proband, segregating with disease in one affected relative. Authors note that this alteration is within a BRCA1 functional domain involved in binding to the y-microtubule protein (Li N et al. Int. J. Gynecol. Cancer;16 Suppl 1:172-178). This variant was not reported in population-based cohorts in the following databases: Database of Single Nucleotide Polymorphisms (dbSNP), the 1000 Genomes Project and the NHLBI Exome Sequencing Project (ESP). This amino acid position is not conserved in available vertebrate species, with valine as the reference amino acid in one species. In addition, this alteration is predicted to be benign and tolerated by PolyPhen and SIFT in silico analyses, respectively.Since supporting evidence is limited at this time, the clinical significance of this variant remains unclear.