chr8-89955500-T-C

Position:

• chr8-89955500-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_002485.5(NBN):​c.1180A>G​(p.Arg394Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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)
• Consequence: NBN NM_002485.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 0.969

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 Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.095065534).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NBN	NM_002485.5	c.1180A>G	p.Arg394Gly	missense_variant	10/16	ENST00000265433.8	NP_002476.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
NBN	ENST00000265433.8	c.1180A>G	p.Arg394Gly	missense_variant	10/16	1	NM_002485.5	ENSP00000265433.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jun 30, 2020

In summary, this variant is a novel missense change that is not predicted to affect protein function. There is no indication that it causes disease, but the available evidence is currently insufficient to prove that conclusively. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function output the following: (SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0"). The glycine amino acid residue is found in multiple mammalian species, suggesting that this missense change does not adversely affect protein function. These predictions have not been confirmed by published functional studies. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with an NBN-related disease. This sequence change replaces arginine with glycine at codon 394 of the NBN protein (p.Arg394Gly). The arginine residue is moderately conserved and there is a moderate physicochemical difference between arginine and glycine. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 15, 2021

The p.R394G variant (also known as c.1180A>G), located in coding exon 10 of the NBN gene, results from an A to G substitution at nucleotide position 1180. The arginine at codon 394 is replaced by glycine, an amino acid with dissimilar properties. This amino acid position is not 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	0.080
BayesDel_addAF	Benign	-0.21	T
BayesDel_noAF	Benign	-0.53
CADD	Benign	12
DANN	Benign	0.92
DEOGEN2	Benign	0.16	T;T
Eigen	Benign	-0.84
Eigen_PC	Benign	-0.90
FATHMM_MKL	Benign	0.056	N
LIST_S2	Benign	0.65	T;T
M_CAP	Benign	0.014	T
MetaRNN	Benign	0.095	T;T
MetaSVM	Benign	-0.96	T
MutationAssessor	Benign	2.0	M;.
PrimateAI	Benign	0.24	T
PROVEAN	Benign	-1.6	N;N
REVEL	Benign	0.047
Sift	Benign	0.15	T;T
Sift4G	Benign	0.25	T;T
Polyphen		0.0	B;.
Vest4		0.12
MutPred		0.34		Loss of MoRF binding (P = 0.0059);.;
MVP		0.64
MPC		0.085
ClinPred		0.048	T
GERP RS		0.30
Varity_R		0.062
gMVP		0.32

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: rs1060503470; hg19: chr8-90967728; COSMIC: COSV55373985; COSMIC: COSV55373985;