8-89953381-T-C

Position:

• chr8-89953381-T-C

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_002485.5(NBN):​c.1708A>G​(p.Thr570Ala) 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:4
• Conservation: PhyloP100: -0.0500

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 -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.05096194).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NBN	NM_002485.5	c.1708A>G	p.Thr570Ala	missense_variant	11/16	ENST00000265433.8	NP_002476.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
NBN	ENST00000265433.8	c.1708A>G	p.Thr570Ala	missense_variant	11/16	1	NM_002485.5	ENSP00000265433.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 29, 2022	This sequence change replaces threonine, which is neutral and polar, with alanine, which is neutral and non-polar, at codon 570 of the NBN protein (p.Thr570Ala). 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: 182725). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Tolerated"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The alanine 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, 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

Jan 09, 2019

This variant is denoted NBN c.1708A>G at the cDNA level, p.Thr570Ala (T570A) at the protein level, and results in the change of a Threonine to an Alanine (ACA>GCA). This variant has not, to our knowledge, been published in the literature as pathogenic or benign. NBN Thr570Ala was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. Since Threonine and Alanine differ in polarity, charge, size or other properties, this is considered a non-conservative amino acid substitution. NBN Thr570Ala occurs at a position that is variable across species and is not located in a known functional domain. In silico analyses predict that this variant is unlikely to alter protein structure or function. Based on currently available information, it is unclear whether NBN Thr570Ala is pathogenic or benign. We consider it to be a variant of uncertain significance. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 11, 2023

The p.T570A variant (also known as c.1708A>G), located in coding exon 11 of the NBN gene, results from an A to G substitution at nucleotide position 1708. The threonine at codon 570 is replaced by alanine, an amino acid with similar 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	0.071
BayesDel_addAF	Benign	-0.28	T
BayesDel_noAF	Benign	-0.65
CADD	Benign	8.3
DANN	Benign	0.93
DEOGEN2	Benign	0.17	T;T
Eigen	Benign	-1.1
Eigen_PC	Benign	-1.1
FATHMM_MKL	Benign	0.033	N
LIST_S2	Benign	0.43	T;T
M_CAP	Benign	0.011	T
MetaRNN	Benign	0.051	T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	1.9	L;.
PrimateAI	Benign	0.32	T
PROVEAN	Benign	-1.2	N;N
REVEL	Benign	0.023
Sift	Benign	0.32	T;T
Sift4G	Benign	0.48	T;T
Polyphen		0.21	B;.
Vest4		0.046
MutPred		0.21		Gain of loop (P = 0.002);.;
MVP		0.50
MPC		0.067
ClinPred		0.062	T
GERP RS		-0.38
Varity_R		0.017
gMVP		0.11

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: rs730881854; hg19: chr8-90965609;