chr8-89946285-T-C

Position:

• chr8-89946285-T-C

Variant summary

Our verdict is Likely benign. Variant got -4 ACMG points: 0P and 4B. BP4_Strong

The NM_002485.5(NBN):​c.1925A>G​(p.Lys642Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000133 in 1,430,002 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000013 (0 hom.)
• Consequence: NBN NM_002485.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:8
• Conservation: PhyloP100: 0.0950

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 (HGNC:):

ACMG classification

Verdict is Likely_benign. Variant got -4 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.04663956).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NBN	NM_002485.5	c.1925A>G	p.Lys642Arg	missense_variant	13/16	ENST00000265433.8	NP_002476.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
NBN	ENST00000265433.8	c.1925A>G	p.Lys642Arg	missense_variant	13/16	1	NM_002485.5	ENSP00000265433.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000199 AC: 5 AN: 251052 Hom.: 0 AF XY: 0.0000221 AC XY: 3 AN XY: 135728

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000868

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000881

Gnomad OTH exome AF: 0.000164

GnomAD4 exome AF: 0.0000133 AC: 19 AN: 1430002 Hom.: 0 Cov.: 32 AF XY: 0.0000126 AC XY: 9 AN XY: 713068

Gnomad4 AFR exome AF: 0.0000610

Gnomad4 AMR exome AF: 0.0000672

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: 0.0000120

Gnomad4 OTH exome AF: 0.0000168

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:8

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency Uncertain:4

Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 13, 2018	This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 13, 2023	This sequence change replaces lysine, which is basic and polar, with arginine, which is basic and polar, at codon 642 of the NBN protein (p.Lys642Arg). This variant is present in population databases (rs587781547, gnomAD 0.009%). This missense change has been observed in individual(s) with clinical features of NBN-related conditions (PMID: 29522266). ClinVar contains an entry for this variant (Variation ID: 141169). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Not Available"; PolyPhen-2: "Benign"; Align-GVGD: "Not Available". The arginine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. 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.	Nov 20, 2020	- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Dec 14, 2023

Variant summary: NBN c.1925A>G (p.Lys642Arg) results in a conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 2e-05 in 251052 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.1925A>G has been reported in the literature in individuals from cancer cohort studies without strong evidence for causality (examples: Bova_2016, Belhadj_2023). These report(s) do not provide unequivocal conclusions about association of the variant with Hereditary Breast And Ovarian Cancer Syndrome. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 36346689, 27148588). Five submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

NBN-related disorder Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

Feb 20, 2024

The NBN c.1925A>G variant is predicted to result in the amino acid substitution p.Lys642Arg. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.0087% of alleles in individuals of Latino descent in gnomAD and is listed in ClinVar as a variant of uncertain significance (https://www.ncbi.nlm.nih.gov/clinvar/variation/141169/). At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Malignant tumor of prostate Uncertain:1

Uncertain significance, no assertion criteria provided

research

Prostate Cancer Research Center, Institute of Biosciences and Medical Technology, University of Tampere

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- -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 19, 2024

The p.K642R variant (also known as c.1925A>G), located in coding exon 13 of the NBN gene, results from an A to G substitution at nucleotide position 1925. The lysine at codon 642 is replaced by arginine, an amino acid with highly similar properties. This alteration was detected in 1/5589 German BRCA1/2-negative probands with breast cancer (Hauke J et al. Cancer Med. 2018 04;7:1349-1358). This amino acid position is poorly 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	0.073
BayesDel_addAF	Benign	-0.44	T
BayesDel_noAF	Benign	-0.67
CADD	Benign	5.8
DANN	Benign	0.91
DEOGEN2	Benign	0.11	T;T
Eigen	Benign	-1.3
Eigen_PC	Benign	-1.3
FATHMM_MKL	Benign	0.074	N
LIST_S2	Benign	0.32	T;T
M_CAP	Benign	0.012	T
MetaRNN	Benign	0.047	T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	0.55	N;.
PrimateAI	Benign	0.24	T
PROVEAN	Benign	-0.72	N;N
REVEL	Benign	0.012
Sift	Benign	0.17	T;T
Sift4G	Benign	0.29	T;T
Polyphen		0.0	B;.
Vest4		0.029
MutPred		0.28		Loss of ubiquitination at K642 (P = 2e-04);.;
MVP		0.52
MPC		0.057
ClinPred		0.039	T
GERP RS		-2.3
Varity_R		0.025
gMVP		0.097

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.15		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: rs587781547; hg19: chr8-90958513; COSMIC: COSV55372637;