17-43063957-G-T
Variant summary
Our verdict is Likely benign. The variant received -5 ACMG points: 0P and 5B. BP4_StrongBP6
The NM_007294.4(BRCA1):c.5075-6C>A variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000217 in 1,613,610 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
Frequency
Consequence
NM_007294.4 splice_region, intron
Scores
Clinical Significance
Conservation
Publications
- breast-ovarian cancer, familial, susceptibility to, 1Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, ClinGen, Labcorp Genetics (formerly Invitae), Genomics England PanelApp
- Fanconi anemia, complementation group SInheritance: AR Classification: DEFINITIVE, STRONG, MODERATE, LIMITED Submitted by: G2P, Labcorp Genetics (formerly Invitae), ClinGen, Ambry Genetics
- pancreatic cancer, susceptibility to, 4Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
- hereditary breast ovarian cancer syndromeInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- Fanconi anemiaInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
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ACMG classification
Our verdict: Likely_benign. The variant received -5 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000263 AC: 4AN: 152158Hom.: 0 Cov.: 32 show subpopulations
GnomAD2 exomes AF: 0.00000797 AC: 2AN: 250974 AF XY: 0.00000737 show subpopulations
GnomAD4 exome AF: 0.0000212 AC: 31AN: 1461452Hom.: 0 Cov.: 31 AF XY: 0.0000179 AC XY: 13AN XY: 727044 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.0000263 AC: 4AN: 152158Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0AN XY: 74342 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
Breast-ovarian cancer, familial, susceptibility to, 1 Uncertain:2Benign:1
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The BRCA1 c.5075-6C>A intronic change results from a C to A substitution at the -6 position of intron 16 of the BRCA1 gene. Splice predictors are not conclusive as to whether or not this variant affects splicing. This variant is absent in gnomAD v2.1.1 (https://gnomad.broadinstitute.org/). This variant is absent in the FLOSSIES database which contains genetic variants from women older than 70 years of age who have never had cancer (https://whi.color.com/). This variant has not been reported in individuals with hereditary breast and ovarian cancer or Fanconi anemia. In summary, the evidence currently available is insufficient to determine the clinical significance of this variant. It has therefore been classified as of uncertain significance. -
not provided Uncertain:2
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This variant is denoted BRCA1 c.5075-6C>A or IVS16-6C>A and consists of a C>A nucleotide substitution at the -6 position of intron 16 of the BRCA1 gene. Using alternate nomenclature, this variant would be defined as BRCA1 5194-6C>A. In silico analyses, which include splice predictors and evolutionary conservation, are inconsistent in their assessment as to whether or not the variant is damaging. BRCA1 5194-6C>A has not, to our knowledge, been published in the literature as a pathogenic or benign germline variant. This variant was not observed at a significant allele frequency in large population cohorts (Lek 2016). Based on currently available evidence, it is unclear whether BRCA1 c.5075-6C>A is a pathogenic or benign variant. We consider it to be a variant of uncertain significance. -
Hereditary breast ovarian cancer syndrome Uncertain:1Benign:1
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The BRCA1 c.5075-6C>A intronic change results from a a C to A substitution at the +6 position of intron 16 of the BRCA1 gene. Splice predictors are not inclusive as to whether or not this variant affects splicing and loss of function of the resulting protein product. Internal RNA data cannot conclusively determine the impact of this variant based on a low number of mutant reads (internal data). This variant is absent in gnomAD v2.1.1 (PM2_Supporting; https://gnomad.broadinstitute.org/). This variant is absent in the FLOSSIES database which contains genetic variants from women older than 70 years of age who have never had cancer (https://whi.color.com/). In summary, this variant meets criteria to be classified as of uncertain significance based on the ACMG/AMP criteria: PM2_Supporting. -
not specified Benign:1
Variant summary: BRCA1 c.5075-6C>A alters a non-conserved nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Several computational tools predict a significant impact on normal splicing: Three predict the variant weakens a 3' acceptor site. However, one study confirmed the variant had no impact on normal splicing in RNA from blood, confirmed by RT-PCR, Sanger sequncing, and gel electrophoresis (e.g. Wai_2020). The variant allele was found at a frequency of 8e-06 in 250974 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.5075-6C>A in individuals affected with Hereditary Breast And Ovarian Cancer Syndrome has been reported. At least one functional study reports experimental evidence evaluating an impact on protein function and showed no damaging effect of this variant on homology directed repair (HDR) activity (e.g. Findlay_2018). HDR assays qualify as a recognized gold standard on the basis of updated guidance provided by the ClinGen Sequence Variant Interpretation (SVI) working group. The following publications have been ascertained in the context of this evaluation (PMID: 30209399, 32123317). ClinVar contains an entry for this variant (Variation ID: 37634). Based on the evidence outlined above, the variant was classified as likely benign. -
Hereditary cancer-predisposing syndrome Benign:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at