8-89953605-G-A

Variant names:

• chr8-89953605-G-A
• rs863224714
• NM_002485.5:c.1484C>T

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 0P and 1B. BP4

The NM_002485.5(NBN):​c.1484C>T​(p.Pro495Leu) variant causes a missense change. The variant allele was found at a frequency of 0.0000105 in 1,613,292 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 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. P495S) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000096 (0 hom.)
• Consequence: NBN NM_002485.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:9
• Conservation: PhyloP100: 4.92
• Publications: 2 publications found

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

ACMG classification

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

• BP4: Computational evidence support a benign effect (MetaRNN=0.2789816).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_002485.5. 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
	NBN	NM_002485.5	MANE Select	c.1484C>T	p.Pro495Leu	missense	Exon 11 of 16	NP_002476.2
	NBN	NM_001024688.3		c.1238C>T	p.Pro413Leu	missense	Exon 12 of 17	NP_001019859.1
	NBN	NM_001440379.1		c.1238C>T	p.Pro413Leu	missense	Exon 11 of 16	NP_001427308.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	NBN	ENST00000265433.8	TSL:1 MANE Select	c.1484C>T	p.Pro495Leu	missense	Exon 11 of 16	ENSP00000265433.4
	NBN	ENST00000697309.1		c.1484C>T	p.Pro495Leu	missense	Exon 11 of 15	ENSP00000513244.1
	NBN	ENST00000697293.1		c.1484C>T	p.Pro495Leu	missense	Exon 11 of 17	ENSP00000513230.1

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152066 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000441

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000958 AC: 14 AN: 1461226 Hom.: 0 Cov.: 32 AF XY: 0.00000963 AC XY: 7 AN XY: 726920

African (AFR) AF: 0.00 AC: 0 AN: 33466

American (AMR) AF: 0.00 AC: 0 AN: 44704

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26124

East Asian (EAS) AF: 0.00 AC: 0 AN: 39668

South Asian (SAS) AF: 0.00 AC: 0 AN: 86228

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53246

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 0.0000126 AC: 14 AN: 1111658

Other (OTH) AF: 0.00 AC: 0 AN: 60368

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152066 Hom.: 0 Cov.: 32 AF XY: 0.0000269 AC XY: 2 AN XY: 74280

African (AFR) AF: 0.00 AC: 0 AN: 41400

American (AMR) AF: 0.00 AC: 0 AN: 15262

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5204

South Asian (SAS) AF: 0.00 AC: 0 AN: 4826

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10604

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000441 AC: 3 AN: 67988

Other (OTH) AF: 0.00 AC: 0 AN: 2086

Alfa AF: 0.0000340 Hom.: 0

Bravo AF: 0.0000151

EpiCase AF: 0.0000545

EpiControl AF: 0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:9

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency Uncertain:3

Sep 03, 2020

Natera, Inc.

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

Nov 07, 2021

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Oct 29, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 495 of the NBN protein (p.Pro495Leu). This variant is present in population databases (no rsID available, gnomAD 0.007%). This missense change has been observed in individual(s) with colorectal cancer (PMID: 27978560). ClinVar contains an entry for this variant (Variation ID: 216564). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. 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.

not provided Uncertain:2

Dec 22, 2022

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The frequency of this variant in the general population, 0.000032 (1/31372 chromosomes, http://gnomad.broadinstitute.org), is uninformative in assessment of its pathogenicity. This variant has been reported in an individual with colon cancer (PMID: 27978560 (2016)). In a large-scale breast cancer association study, the variant was observed in individuals with breast cancer (PMID: 33471991 (2021), see also LOVD (http://databases.lovd.nl/shared/genes/NBN)). Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded conflicting predictions that this variant is benign or damaging. Based on the available information, we are unable to determine the clinical significance of this variant.

Feb 25, 2022

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at a significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Observed in individuals with colon cancer (Pearlman 2017); This variant is associated with the following publications: (PMID: 27978560)

Hereditary cancer-predisposing syndrome Uncertain:2

Apr 14, 2021

Sema4, Sema4

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: curation

May 05, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.P495L variant (also known as c.1484C>T), located in coding exon 11 of the NBN gene, results from a C to T substitution at nucleotide position 1484. The proline at codon 495 is replaced by leucine, an amino acid with similar properties. This alteration was previously reported in a male diagnosed with cecal cancer at 39 years old, whose tumor was MMR-proficient (Pearlman R et al. JAMA Oncol. 2017 Apr;3:464-471). 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.

not specified Uncertain:1

Jul 24, 2022

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: NBN c.1484C>T (p.Pro495Leu) results in a non-conservative amino acid change in the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 250652 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.1484C>T has been reported in the literature as a VUS in at-least one mismatch repair (MMR) proficient individual from a cohort undergoing multigene panel testing for early onset colorectal cancer (example, Pearlman_2016). These report(s) do not provide unequivocal conclusions about association of the variant with Nijmegen Breakage Syndrome or NBN-related cancers. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Seven clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance.

Aplastic anemia Uncertain:1

Oct 20, 2023

Baylor Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.089
BayesDel_addAF	Benign	-0.065	T
BayesDel_noAF	Benign	-0.33
CADD	Benign	22
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.47	T
Eigen	Uncertain	0.41
Eigen_PC	Uncertain	0.38
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.88	D
M_CAP	Benign	0.036	D
MetaRNN	Benign	0.28	T
MetaSVM	Benign	-0.43	T
MutationAssessor	Uncertain	2.6	M
PhyloP100		4.9
PrimateAI	Benign	0.37	T
PROVEAN	Uncertain	-3.2	D
REVEL	Benign	0.097
Sift	Uncertain	0.0020	D
Sift4G	Uncertain	0.0070	D
Polyphen		0.94	P
Vest4		0.33
MVP		0.80
MPC		0.32
ClinPred		0.97	D
GERP RS		5.4
PromoterAI		-0.0016	Neutral
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.10
gMVP		0.28
Mutation Taster		=83/17	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: rs863224714; hg19: chr8-90965833;