13-32329491-C-T

Position:

• chr13-32329491-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_000059.4(BRCA2):​c.680C>T​(p.Ala227Val) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000197 in 152,160 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. 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. A227P) has been classified as Uncertain significance.

• Frequency: Genomes: 𝑓 0.000020 (0 hom., cov: 32)
• Consequence: BRCA2 NM_000059.4 missense, splice_region
• Scores: Splicing: ADA: 0.00006719
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:5 B:1
• Conservation: PhyloP100: 0.381

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 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.09228328).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
BRCA2	NM_000059.4	c.680C>T	p.Ala227Val	missense_variant, splice_region_variant	8/27	ENST00000380152.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
BRCA2	ENST00000380152.8	c.680C>T	p.Ala227Val	missense_variant, splice_region_variant	8/27	5	NM_000059.4	A2

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152160 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000724

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 27

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152160 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74334

Gnomad4 AFR AF: 0.0000724

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000151

ESP6500AA AF: 0.000227 AC: 1

ESP6500EA AF: 0.00 AC: 0

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	GeneDx	Apr 28, 2016	This variant is denoted BRCA2 c.680C>T at the cDNA level, p.Ala227Val (A227V) at the protein level, and results in the change of an Alanine to a Valine (GCT>GTT). Using alternate nomenclature, this variant would be defined as BRCA2 908C>T. BRCA2 Ala227Val occurs at the second to last position with its exon and was selected for splicing analysis by de Garibay et al. (2014), who did not find this variant to impact splicing on both in silico and in vitro analyses. BRCA2 Ala227Val was not observed at a significant allele frequency in the NHLBI Exome Sequencing Project. Since Alanine and Valine share similar properties, this is considered a conservative amino acid substitution. BRCA2 Ala227Val occurs at a position that is not conserved and is not located in a known functional domain. In silico analyses predict that this variant is unlikely to alter protein structure or function. Based on currently available evidence, it is unclear whether BRCA2 Ala227Val is pathogenic or benign. We consider it to be a variant of uncertain significance. -
Uncertain significance, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Mar 26, 2019	- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Sep 18, 2023

Variant summary: BRCA2 c.680C>T (p.Ala227Val) results in a non-conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a benign effect of the variant on protein function. The variant was absent in 243714 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.680C>T has been reported in the literature in individuals with Hereditary Breast And Ovarian Cancer Syndrome, without strong evidence for causality (example, de Garibay_2014, Rodriguez-Balada_2016). It was also reported in an unaffected individual in a large case-control study of Breast cancer (PMID: 33471991). These report(s) do not provide unequivocal conclusions about association of the variant with Hereditary Breast And Ovarian Cancer Syndrome. At least one publication reports experimental evidence evaluating an impact on RNA splicing. RT-PCR of patient RNA showed the variant had no effect on splicing (de Garibay_2014). The following publications have been ascertained in the context of this evaluation (PMID: 27886673, 24123850, 33471991). Four submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jul 20, 2023

The p.A227V variant (also known as c.680C>T), located in coding exon 7 of the BRCA2 gene, results from a C to T substitution at nucleotide position 680. The alanine at codon 227 is replaced by valine, an amino acid with similar properties. This alteration was identified in 1/710 high-risk hereditary breast and ovarian cancer families (Rodríguez-Balada M et al. Cancer Genet. 2016 Nov;209:487-492). A study using capillary electrophoresis of semi-quantitative RT-PCR assays of BRCA2 splicing alterations demonstrated similar patterns of splicing in wild-type controls and c.680C>T carriers; subsequent direct sequencing also confirmed bi-allelic expression in c.680C>T carriers (de Garibay GR et al. Hum. Mutat. 2014 Jan;35:53-7). This amino acid position is not well conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Hereditary breast ovarian cancer syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

May 26, 2023

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Not Available"; PolyPhen-2: "Benign"; Align-GVGD: "Not Available". The valine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. ClinVar contains an entry for this variant (Variation ID: 182179). This variant has not been reported in the literature in individuals affected with BRCA2-related conditions. This variant is present in population databases (rs149565664, gnomAD 0.004%). This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 227 of the BRCA2 protein (p.Ala227Val). -

Breast-ovarian cancer, familial, susceptibility to, 2 Benign:1

Likely benign, criteria provided, single submitter

clinical testing

All of Us Research Program, National Institutes of Health

Aug 15, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Benign	-0.040	T
BayesDel_noAF	Benign	-0.30
CADD	Benign	18
DANN	Uncertain	0.99
Eigen	Benign	-0.56
Eigen_PC	Benign	-0.50
FATHMM_MKL	Benign	0.16	N
M_CAP	Benign	0.033	D
MetaRNN	Benign	0.092	T;T
MetaSVM	Benign	-0.94	T
MutationTaster	Benign	0.96	N;N
PrimateAI	Benign	0.25	T
PROVEAN	Benign	-0.56	N;N
REVEL	Benign	0.18
Sift	Benign	0.094	T;T
Sift4G	Benign	0.089	T;T
Vest4		0.22
MVP		0.78
MPC		0.021
ClinPred		0.095	T
GERP RS		-1.2
gMVP		0.12

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.000067
dbscSNV1_RF	Benign	0.076
SpliceAI score (max)		0.020		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: rs149565664; hg19: chr13-32903628;