13-32338632-C-G

Variant names:

• chr13-32338632-C-G
• rs748591104
• NM_000059.4:c.4277C>G

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 2P and 3B. PM2 BP4_Moderate BP6

The NM_000059.4(BRCA2):​c.4277C>G​(p.Thr1426Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000691 in 1,446,394 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/20 in silico tools predict a benign 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. T1426K) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: BRCA2 NM_000059.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: -0.0260
• Publications: 0 publications found

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]

BRCA2 Gene-Disease associations (from GenCC):

• breast-ovarian cancer, familial, susceptibility to, 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Genomics England PanelApp, Labcorp Genetics (formerly Invitae), ClinGen
• Fanconi anemia complementation group D1

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, ClinGen, G2P
• pancreatic cancer, susceptibility to, 2

  Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
• sarcoma

  Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
• hereditary breast ovarian cancer syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Fanconi anemia

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• medulloblastoma

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics

ACMG classification

Our verdict: Likely_benign. The variant received -1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.14587277).
• BP6: Variant 13-32338632-C-G is Benign according to our data. Variant chr13-32338632-C-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 1347470.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000059.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	BRCA2	NM_000059.4	MANE Select	c.4277C>G	p.Thr1426Arg	missense	Exon 11 of 27	NP_000050.3
	BRCA2	NM_001432077.1		c.4277C>G	p.Thr1426Arg	missense	Exon 11 of 27	NP_001419006.1
	BRCA2	NM_001406720.1		c.4277C>G	p.Thr1426Arg	missense	Exon 11 of 27	NP_001393649.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	BRCA2	ENST00000380152.8	TSL:5 MANE Select	c.4277C>G	p.Thr1426Arg	missense	Exon 11 of 27	ENSP00000369497.3
	BRCA2	ENST00000544455.6	TSL:1	c.4277C>G	p.Thr1426Arg	missense	Exon 11 of 27	ENSP00000439902.1
	BRCA2	ENST00000530893.7	TSL:1	c.3908C>G	p.Thr1303Arg	missense	Exon 11 of 27	ENSP00000499438.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.91e-7 AC: 1 AN: 1446394 Hom.: 0 Cov.: 35 AF XY: 0.00000140 AC XY: 1 AN XY: 716590

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 32916

American (AMR) AF: 0.00 AC: 0 AN: 43562

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25892

East Asian (EAS) AF: 0.00 AC: 0 AN: 39334

South Asian (SAS) AF: 0.00 AC: 0 AN: 83690

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53242

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5716

European-Non Finnish (NFE) AF: 9.07e-7 AC: 1 AN: 1102364

Other (OTH) AF: 0.00 AC: 0 AN: 59678

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Hereditary breast ovarian cancer syndrome Uncertain:1

Nov 14, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site, but this prediction has not been confirmed by published transcriptional studies. This sequence change replaces threonine with arginine at codon 1426 of the BRCA2 protein (p.Thr1426Arg). The threonine residue is weakly conserved and there is a moderate physicochemical difference between threonine and arginine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with BRCA2-related conditions. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt BRCA2 protein function. 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.

Hereditary cancer-predisposing syndrome Benign:1

Mar 23, 2023

University of Washington Department of Laboratory Medicine, University of Washington

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: curation

Missense variant in a coldspot region where missense variants are very unlikely to be pathogenic (PMID:31911673).

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.088
BayesDel_addAF	Benign	-0.052	T
BayesDel_noAF	Benign	-0.31
CADD	Benign	0.093
DANN	Benign	0.72
Eigen	Benign	-1.1
Eigen_PC	Benign	-0.99
FATHMM_MKL	Benign	0.094	N
M_CAP	Benign	0.068	D
MetaRNN	Benign	0.15	T
MetaSVM	Benign	-0.91	T
PhyloP100		-0.026
PrimateAI	Benign	0.25	T
PROVEAN	Benign	-1.2	N
REVEL	Benign	0.27
Sift	Benign	0.23	T
Sift4G	Benign	0.68	T
Vest4		0.20
MutPred		0.60		Loss of phosphorylation at T1426 (P = 0.0541)
MVP		0.83
MPC		0.028
ClinPred		0.080	T
GERP RS		3.4
gMVP		0.11
Mutation Taster		=90/10	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs748591104; hg19: chr13-32912769;