chr8-89964449-T-C

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_002485.5(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
NM_002485.5 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:5

Conservation

PhyloP100: 5.02

Publications

1 publications found

Variant links:

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]

NBN Gene-Disease associations (from GenCC):

Nijmegen breakage syndrome
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Labcorp Genetics (formerly Invitae), ClinGen, Myriad Women’s Health
rhabdomyosarcoma
Inheritance: AR Classification: MODERATE Submitted by: Genomics England PanelApp
idiopathic aplastic anemia
Inheritance: AD Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)
prostate cancer
Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
hereditary breast carcinoma
Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

NBN links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NBN	NM_002485.5 link	c.955A>G	p.Thr319Ala	missense_variant	Exon 8 of 16	ENST00000265433.8	NP_002476.2	O60934

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NBN	ENST00000265433.8 link	c.955A>G	p.Thr319Ala	missense_variant	Exon 8 of 16	1	NM_002485.5	ENSP00000265433.4		O60934

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461458

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727062

show subpopulations

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

African (AFR)

AF:

0.00

AC:

AN:

33458

American (AMR)

AF:

0.00

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26124

East Asian (EAS)

AF:

0.00

AC:

AN:

39648

South Asian (SAS)

AF:

0.00

AC:

AN:

86256

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53392

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5764

European-Non Finnish (NFE)

AF:

9.00e-7

AC:

AN:

1111726

Other (OTH)

AF:

0.00

AC:

AN:

60370

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.375

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency

Uncertain:3

Nov 07, 2021

Genome-Nilou Lab

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jun 03, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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. -

Sep 08, 2021

Natera, Inc.

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

not provided

Uncertain:1

Mar 03, 2022

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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

May 08, 2025

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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

BayesDel_noAF

Benign

-0.23

CADD

Benign

(source)

DANN

Uncertain

0.99

DEOGEN2

Benign

0.31

T;T

Eigen

Benign

0.11

Eigen_PC

Uncertain

0.25

FATHMM_MKL

Uncertain

0.91

LIST_S2

Benign

0.81

T;T

M_CAP

Benign

0.038

MetaRNN

Uncertain

0.71

D;D

MetaSVM

Benign

-0.50

MutationAssessor

Uncertain

2.5

M;.

PhyloP100

5.0

PrimateAI

Benign

0.41

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

GERP RS

5.5

Varity_R

0.12

gMVP

0.38

Mutation Taster

=75/25

polymorphism

(source)

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

You must be logged in to view publications. This limit was set because tens of millions (!) of queries from AI bots are generated daily.

chr8-89964449-T-C

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over