Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong
The NM_007294.4(BRCA1):c.4357+2T>G variant causes a splice donor, intron 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. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).
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]
Verdict is Pathogenic. Variant got 18 ACMG points.
PVS1
Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
PM2
Very rare variant in population databases, with high coverage;
PP5
Variant 17-43082402-A-C is Pathogenic according to our data. Variant chr17-43082402-A-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 91629.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
The c.4357+2T>G intronic pathogenic mutation results from a T to G substitution two nucleotides after coding exon 11 in the BRCA1 gene. This alteration has been observed in ovarian cancer cohorts (Ratajska M et al. J Appl Genet 2015 May;56(2):193-8; Koczkowska M et al. Cancer Med 2016 Jul;5(7):1640-6). This nucleotide position is well conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice donor site. Other alterations impacting the same donor site (c.4357+1G>A, c.4357+1G>T) have been shown to have a similar impact on splicing (Ambry internal data; Thomassen M et al. Breast Cancer Res Treat 2012 Apr;132:1009-23; Menéndez M et al. Breast Cancer Res Treat 2012 Apr;132(3):979-92). Alterations that disrupt the canonical splice site are expected to cause aberrant splicing, resulting in an abnormal protein or a transcript that is subject to nonsense-mediated mRNA decay. As such, this alteration is classified as a disease-causing mutation. -
Likely pathogenic, criteria provided, single submitter
clinical testing
Color Diagnostics, LLC DBA Color Health
Feb 09, 2022
This variant causes a T to G nucleotide substitution at the +2 position of intron 12 of the BRCA1 gene. This variant is also known as IVS13+2T>G based on Breast Cancer Information Core (BIC) nomenclature. Splice site prediction tools predict that this variant may have a significant impact on RNA splicing. Although this prediction has not been confirmed in published RNA studies, this variant is expected to result in an absent or disrupted protein product. This variant has been reported in individuals affected with ovarian cancer (PMID: 25366421, 27167707), and in hereditary breast cancer families (PMID: 27983536). This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Different variants affecting the same splice donor site, c.4357+2T>A, c.4357+2T>C, c.4357+1G>A, c.4357+1G>C and c.4357+1G>T, are known to be disease-causing (ClinVar variation ID: 1076429, 55180, 37584, 55177, 55178). Loss of BRCA1 function is a known mechanism of disease (clinicalgenome.org). Based on the available evidence, this variant is classified as Likely Pathogenic. -
not provided Pathogenic:1
Pathogenic, criteria provided, single submitter
clinical testing
GeneDx
Aug 16, 2016
This variant is denoted BRCA1 c.4357+2T>G or IVS12+2T>G and consists of a T>G nucleotide substitution at the +2 position of intron 12 of the BRCA1 gene. Using alternate nomenclature, this variant would be defined as/ has previously been published as BRCA1 4476+2T>G. This variant destroys a canonical splice donor site and is predicted to cause abnormal gene splicing, leading to either an abnormal message that is subject to nonsense-mediated mRNA decay or to an abnormal protein product. This variant has been reported in at least two women with a history of serous ovarian cancer (Ratajska 2015, Koczkowska 2016) We consider this variant to be pathogenic. Based on the current evidence, we consider this variant to be pathogenic. -
Hereditary breast ovarian cancer syndrome Pathogenic:1
Pathogenic, criteria provided, single submitter
clinical testing
Labcorp Genetics (formerly Invitae), Labcorp
Oct 28, 2022
For these reasons, this variant has been classified as Pathogenic. Studies have shown that disruption of this splice site alters mRNA splicing and is expected to lead to the loss of protein expression (PMID: 21735045, 24667779). ClinVar contains an entry for this variant (Variation ID: 91629). Disruption of this splice site has been observed in individual(s) with ovarian cancer (PMID: 25366421, 27167707). This variant is not present in population databases (gnomAD no frequency). This sequence change affects a donor splice site in intron 12 of the BRCA1 gene. RNA analysis indicates that disruption of this splice site induces altered splicing and may result in an absent or disrupted protein product. -