rs876659969

Positions:

• chr8-89964449-T-C

Variant summary

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

The ENST00000265433.8(NBN):​c.955A>G​(p.Thr319Ala) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,458 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T319I) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: NBN ENST00000265433.8 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: 5.02

Genes affected

NBN (HGNC:7652): (nibrin) Mutations in this gene are associated with Nijmegen breakage syndrome, an autosomal recessive chromosomal instability syndrome characterized by microcephaly, growth retardation, immunodeficiency, and cancer predisposition. The encoded protein is a member of the MRE11/RAD50 double-strand break repair complex which consists of 5 proteins. This gene product is thought to be involved in DNA double-strand break repair and DNA damage-induced checkpoint activation. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NBN	NM_002485.5	c.955A>G	p.Thr319Ala	missense_variant	8/16	ENST00000265433.8	NP_002476.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
NBN	ENST00000265433.8	c.955A>G	p.Thr319Ala	missense_variant	8/16	1	NM_002485.5	ENSP00000265433	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461458 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 727062

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: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jun 03, 2022	This sequence change replaces threonine, which is neutral and polar, with alanine, which is neutral and non-polar, at codon 319 of the NBN protein (p.Thr319Ala). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with NBN-related conditions. ClinVar contains an entry for this variant (Variation ID: 232754). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. 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. -
Uncertain significance, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 08, 2021	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Mar 03, 2022

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge; This variant is associated with the following publications: (PMID: 24894818) -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 24, 2021

The p.T319A variant (also known as c.955A>G), located in coding exon 8 of the NBN gene, results from an A to G substitution at nucleotide position 955. The threonine at codon 319 is replaced by alanine, an amino acid with similar properties. This amino acid position is 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.16
BayesDel_addAF	Benign	0.0050	T
BayesDel_noAF	Benign	-0.23
CADD	Benign	23
DANN	Uncertain	0.99
DEOGEN2	Benign	0.31	T;T
Eigen	Benign	0.11
Eigen_PC	Uncertain	0.25
FATHMM_MKL	Uncertain	0.91	D
LIST_S2	Benign	0.81	T;T
M_CAP	Benign	0.038	D
MetaRNN	Uncertain	0.71	D;D
MetaSVM	Benign	-0.50	T
MutationAssessor	Uncertain	2.5	M;.
MutationTaster	Benign	0.80	D;D
PrimateAI	Benign	0.41	T
PROVEAN	Uncertain	-2.5	N;D
REVEL	Benign	0.11
Sift	Benign	0.031	D;D
Sift4G	Benign	0.14	T;T
Polyphen		0.017	B;.
Vest4		0.74
MutPred		0.30		Loss of glycosylation at T319 (P = 0.082);.;
MVP		0.80
MPC		0.078
ClinPred		0.95	D
GERP RS		5.5
Varity_R		0.12
gMVP		0.38

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: rs876659969; hg19: chr8-90976677;