chr13-32362656-C-G

Position:

• chr13-32362656-C-G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM5 PP3

The NM_000059.4(BRCA2):​c.7939C>G​(p.Leu2647Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000164 in 1,461,876 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic 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. L2647?) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000016 (0 hom.)
• Consequence: BRCA2 NM_000059.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:5 B:1
• Conservation: PhyloP100: 1.98

Genes affected

BRCA2 (HGNC:1101): (BRCA2 DNA repair associated) Inherited mutations in BRCA1 and this gene, BRCA2, confer increased lifetime risk of developing breast or ovarian cancer. Both BRCA1 and BRCA2 are involved in maintenance of genome stability, specifically the homologous recombination pathway for double-strand DNA repair. The largest exon in both genes is exon 11, which harbors the most important and frequent mutations in breast cancer patients. The BRCA2 gene was found on chromosome 13q12.3 in human. The BRCA2 protein contains several copies of a 70 aa motif called the BRC motif, and these motifs mediate binding to the RAD51 recombinase which functions in DNA repair. BRCA2 is considered a tumor suppressor gene, as tumors with BRCA2 mutations generally exhibit loss of heterozygosity (LOH) of the wild-type allele. [provided by RefSeq, May 2020]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM5: Other missense variant is known to change same aminoacid residue: Variant chr13-32362656-CTA-CC is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.827

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BRCA2	NM_000059.4	c.7939C>G	p.Leu2647Val	missense_variant	17/27	ENST00000380152.8	NP_000050.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BRCA2	ENST00000380152.8	c.7939C>G	p.Leu2647Val	missense_variant	17/27	5	NM_000059.4	ENSP00000369497	A2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.0000164 AC: 24 AN: 1461876 Hom.: 0 Cov.: 33 AF XY: 0.0000124 AC XY: 9 AN XY: 727234

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000216

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:5 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Mar 07, 2018	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Sep 28, 2023	Identified in a high-risk breast cancer family (Byers et al., 2016); Published functional studies demonstrate no impact on splicing (Byers et al., 2016); Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant does not alter protein structure/function; Also known as 8167C>G; This variant is associated with the following publications: (PMID: 12228710, 27273131) -

Hereditary cancer-predisposing syndrome Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Jun 02, 2023	This missense variant replaces leucine with valine at codon 2647 in the DNA binding domain of the BRCA2 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). This variant has been reported to be functional in a haploidized cell proliferation assay (PMID: 35190686). This variant has been reported in an individual affected with breast cancer and in an unaffected individual (PMID: 27273131, 33471991; Leiden Open Variation Database DB-ID BRCA2_003789). This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). A different missense variant at the same amino acid position, p.Leu2647Pro, is considered to be disease-causing (ClinVar variation ID: 52443), suggesting that leucine at this position is important for BRCA2 function. 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	clinical testing	Ambry Genetics	May 08, 2024	The p.L2647V variant (also known as c.7939C>G), located in coding exon 16 of the BRCA2 gene, results from a C to G substitution at nucleotide position 7939. The leucine at codon 2647 is replaced by valine, an amino acid with highly similar properties. This alteration was detected in a woman with a personal history of early onset breast cancer (Byers H et al. Eur. J. Hum. Genet., 2016 11;24:1591-1597). This amino acid position is highly 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. -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Apr 11, 2024

Variant summary: BRCA2 c.7939C>G (p.Leu2647Val) results in a conservative amino acid change located in the Breast cancer type 2 susceptibility protein, helical domain (IPR015252) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 1.6e-05 in 1461876 control chromosomes (gnomAD database v4.0.0). This frequency is not significantly higher than estimated for a pathogenic variant in BRCA2 causing Hereditary Breast And Ovarian Cancer Syndrome (1.6e-05 vs 0.00075), allowing no conclusion about variant significance. c.7939C>G has been reported in the literature in at-least one individual affected with female breast cancer and authors classified the variant as VUS (example: Byers_2016). These report(s) do not provide unequivocal conclusions about association of the variant with Hereditary Breast And Ovarian Cancer Syndrome. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication have been ascertained in the context of this evaluation (PMID: 27273131). ClinVar contains an entry for this variant (Variation ID: 186112). Based on the evidence outlined above, the variant was classified as uncertain significance. -

Hereditary breast ovarian cancer syndrome Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 07, 2024

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.33
BayesDel_addAF	Pathogenic	0.26	D
BayesDel_noAF	Pathogenic	0.14
CADD	Benign	22
DANN	Uncertain	1.0
Eigen	Uncertain	0.53
Eigen_PC	Uncertain	0.44
FATHMM_MKL	Uncertain	0.87	D
M_CAP	Uncertain	0.21	D
MetaRNN	Pathogenic	0.83	D;D
MetaSVM	Uncertain	0.64	D
MutationTaster	Benign	1.0	D;D
PrimateAI	Benign	0.48	T
PROVEAN	Benign	-0.80	N;N
REVEL	Uncertain	0.63
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Vest4		0.66
MutPred		0.69		Loss of catalytic residue at L2647 (P = 0.0243);Loss of catalytic residue at L2647 (P = 0.0243);
MVP		0.91
MPC		0.17
ClinPred		0.98	D
GERP RS		2.5
gMVP		0.42

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs778391123; hg19: chr13-32936793;