17-43115725-CTTGCAAAATATGT-CA

Position:

• chr17-43115725-CTTGCAAAATATGT-CA

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PM4 PP5_Moderate

The ENST00000357654.9(BRCA1):​c.122_134delinsT​(p.His41_Lys45delinsLeu) variant causes a protein altering, splice region change. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. H41H) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: BRCA1 ENST00000357654.9 protein_altering, splice_region
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 4.40

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 Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a hotspot region, there are 7 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 5 benign, 17 uncertain in ENST00000357654.9
• PM2: Very rare variant in population databases, with high coverage
• PM4: Nonframeshift variant in NON repetitive region in ENST00000357654.9.
• PP5: Variant 17-43115726-TTGCAAAATATGT-A is Pathogenic according to our data. Variant chr17-43115726-TTGCAAAATATGT-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 462553.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BRCA1	NM_007294.4	c.122_134delinsT	p.His41_Lys45delinsLeu	protein_altering_variant, splice_region_variant	3/23	ENST00000357654.9	NP_009225.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BRCA1	ENST00000357654.9	c.122_134delinsT	p.His41_Lys45delinsLeu	protein_altering_variant, splice_region_variant	3/23	1	NM_007294.4	ENSP00000350283	P4

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hereditary breast ovarian cancer syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 26, 2017

This variant, c.122_134delinsT, is a complex sequence change that results in the deletion of the last 5 amino acid residues of exon 3 BRCA1 protein and the insertion of 1 residue  (p.His41_Lys45delinsGln). This variant also affects the last nucleotide, which is part of the consensus splice site for this exon. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a BRCA1-related disease. Experimental studies and prediction algorithms are not available for this variant, and the functional significance of the deleted amino acids is currently unknown. However, the deletion removes essential amino acids  from the highly conserved residues of the N-terminal BRCA1 RING domain (PMID: 12732733, 22843421). Nucleotide substitutions within the consensus splice site are relatively common causes of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of nucleotide changes on RNA splicing suggest that this variant may alter RNA splicing, but this prediction has not been confirmed by published transcriptional studies. Different missense substitution at these codons (p.Cys44Phe, p.Cys44Tyr, p.His41Arg) have been determined to be pathogenic (PMID: 23633455, 18159056, 25777348, 16267036 19543972, 27083775, 21922593, 25823446, 15168169, 24489791). This suggests that these residues are critical for BRCA1 protein function and that deletion of these amino acids may also be pathogenic. In summary, this variant is a novel deletion/insertion that removes highly conserved residues of the BRCA1 RING domain that have been determined to be pathogenic. This evidence indicates that the variant is pathogenic, but additional data is needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Splicing

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

Publications

LitVar

Other links and lift over

dbSNP: rs1555599205; hg19: chr17-41267743;