chr13-32326282-G-T

Position:

• chr13-32326282-G-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PM5 PP5_Moderate

The NM_000059.4(BRCA2):​c.516G>T​(p.Lys172Asn) variant causes a missense, splice region change. The variant was absent in control chromosomes in GnomAD project. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. K172?) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: BRCA2 NM_000059.4 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 3.71

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr13-32326281-AGG-AC is described in Lovd as [Pathogenic].
• PP5: Variant 13-32326282-G-T is Pathogenic according to our data. Variant chr13-32326282-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 441345.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr13-32326282-G-T is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BRCA2	NM_000059.4	c.516G>T	p.Lys172Asn	missense_variant, splice_region_variant	6/27	ENST00000380152.8	NP_000050.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BRCA2	ENST00000380152.8	c.516G>T	p.Lys172Asn	missense_variant, splice_region_variant	6/27	5	NM_000059.4	ENSP00000369497.3
BRCA2	ENST00000530893.7	c.147G>T	p.Lys49Asn	missense_variant, splice_region_variant	6/27	1		ENSP00000499438.2
BRCA2	ENST00000614259.2	n.516G>T		splice_region_variant, non_coding_transcript_exon_variant	5/26	2		ENSP00000506251.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hereditary cancer-predisposing syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Jan 05, 2023

The c.516G>T variant (also known as p.K172N), located in coding exon 5 of the BRCA2 gene, results from a G to T substitution at nucleotide position 516. The amino acid change results in lysine to asparagine at codon 172, an amino acid with similar properties. However, this change occurs in the last base pair of coding exon 5, which makes it likely to have some effect on normal mRNA splicing. In silico splice site analysis predicts that this alteration will weaken the native splice donor site; however, direct evidence is insufficient at this time (Ambry internal data). Another alteration impacting the same donor site (BRCA2 c.516G>A) has been shown to result in multiple out-of-frame aberrant transcripts (Hansen TV et al. Breast Cancer Res Treat, 2010 Feb;119:547-50). Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.29
BayesDel_addAF	Benign	-0.078	T
BayesDel_noAF	Benign	-0.35
CADD	Pathogenic	35
DANN	Uncertain	1.0
Eigen	Uncertain	0.59
Eigen_PC	Uncertain	0.56
FATHMM_MKL	Uncertain	0.91	D
M_CAP	Uncertain	0.14	D
MetaRNN	Uncertain	0.47	T;T
MetaSVM	Benign	-0.94	T
PrimateAI	Uncertain	0.52	T
PROVEAN	Benign	-0.99	N;N
REVEL	Benign	0.12
Sift	Uncertain	0.0030	D;D
Sift4G	Uncertain	0.010	D;D
Vest4		0.46
MutPred		0.29		Loss of methylation at K172 (P = 0.0026);Loss of methylation at K172 (P = 0.0026);
MVP		0.93
MPC		0.17
ClinPred		0.90	D
GERP RS		5.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
gMVP		0.21

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.98
SpliceAI score (max)		0.94		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.94		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs80359790; hg19: chr13-32900419;