13-32340798-C-T

Position:

• chr13-32340798-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 4P and 2B. PM2 PM5 BP4_Moderate

The NM_000059.4(BRCA2):​c.6443C>T​(p.Ser2148Phe) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000694 in 1,440,376 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/19 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. S2148Y) has been classified as Pathogenic.

• 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:3 B:1
• Conservation: PhyloP100: -0.529

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 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr13-32340798-C-A is described in Lovd as [Pathogenic].
• BP4: Computational evidence support a benign effect (MetaRNN=0.16584015).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BRCA2	NM_000059.4	c.6443C>T	p.Ser2148Phe	missense_variant	11/27	ENST00000380152.8	NP_000050.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BRCA2	ENST00000380152.8	c.6443C>T	p.Ser2148Phe	missense_variant	11/27	5	NM_000059.4	ENSP00000369497.3
BRCA2	ENST00000530893.7	c.6074C>T	p.Ser2025Phe	missense_variant	11/27	1		ENSP00000499438.2
BRCA2	ENST00000614259.2	n.6443C>T		non_coding_transcript_exon_variant	10/26	2		ENSP00000506251.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.94e-7 AC: 1 AN: 1440376 Hom.: 0 Cov.: 44 AF XY: 0.00000140 AC XY: 1 AN XY: 715686

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: 9.05e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:1 Benign:1

Likely benign, criteria provided, single submitter	curation	University of Washington Department of Laboratory Medicine, University of Washington	Mar 23, 2023	Missense variant in a coldspot region where missense variants are very unlikely to be pathogenic (PMID:31911673). -
Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Oct 31, 2022	This missense variant replaces serine with phenylalanine at codon 2148 of the BRCA2 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with hereditary cancer in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). 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. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Apr 04, 2018

The BRCA2 c.6443C>T; p.Ser2148Phe variant, to our knowledge, is not reported in the medical literature or gene specific databases. This variant is also absent from the general population databases (1000 Genomes Project, Exome Variant Server, and Genome Aggregation Database), indicating it is not a common polymorphism. The serine at codon 2148 is moderately conserved, but computational analyses (SIFT, PolyPhen-2) predict that this variant is tolerated. However, given the lack of clinical and functional data, the significance of the p.Ser2148Phe variant is uncertain at this time. -

Hereditary breast ovarian cancer syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 20, 2019

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: "Tolerated"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The phenylalanine amino acid residue is found in multiple mammalian species, suggesting that this missense change does not adversely affect protein function. These predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with BRCA2-related conditions. ClinVar contains an entry for this variant (Variation ID: 617996). This variant is not present in population databases (ExAC no frequency). This sequence change replaces serine with phenylalanine at codon 2148 of the BRCA2 protein (p.Ser2148Phe). The serine residue is moderately conserved and there is a large physicochemical difference between serine and phenylalanine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.10
BayesDel_addAF	Uncertain	0.070	D
BayesDel_noAF	Benign	-0.14
CADD	Benign	12
DANN	Benign	0.81
Eigen	Benign	-0.87
Eigen_PC	Benign	-0.96
FATHMM_MKL	Benign	0.033	N
M_CAP	Uncertain	0.14	D
MetaRNN	Benign	0.17	T;T
MetaSVM	Benign	-0.83	T
PrimateAI	Benign	0.24	T
PROVEAN	Benign	-1.1	N;N
REVEL	Uncertain	0.49
Sift	Benign	0.037	D;D
Sift4G	Benign	0.46	T;T
Vest4		0.25
MutPred		0.35		Loss of disorder (P = 0.0103);Loss of disorder (P = 0.0103);
MVP		0.84
MPC		0.023
ClinPred		0.037	T
GERP RS		-0.98
gMVP		0.25

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

Publications

LitVar

Other links and lift over

dbSNP: rs80358880; hg19: chr13-32914935; COSMIC: COSV105326814;