8-89953635-G-T

Variant summary

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

The NM_002485.5(NBN):c.1454C>A(p.Thr485Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000411 in 1,460,612 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T485M) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: NBN NM_002485.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 1.01

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]

ACMG classification

Verdict is Likely_benign. Variant got -4 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.056218922).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NBN	NM_002485.5	c.1454C>A	p.Thr485Lys	missense_variant	11/16	ENST00000265433.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NBN	ENST00000265433.8	c.1454C>A	p.Thr485Lys	missense_variant	11/16	1	NM_002485.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000400 AC: 1 AN: 250230 Hom.: 0 AF XY: 0.00000739 AC XY: 1 AN XY: 135246

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

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: 0.00000884

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000411 AC: 6 AN: 1460612 Hom.: 0 Cov.: 32 AF XY: 0.00000413 AC XY: 3 AN XY: 726598

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 0.00000540

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

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

Invitae

Dec 22, 2020

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. 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, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with NBN-related conditions. This variant is present in population databases (rs200891292, ExAC 0.002%). This sequence change replaces threonine with lysine at codon 485 of the NBN protein (p.Thr485Lys). The threonine residue is weakly conserved and there is a moderate physicochemical difference between threonine and lysine. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 01, 2022

The p.T485K variant (also known as c.1454C>A), located in coding exon 11 of the NBN gene, results from a C to A substitution at nucleotide position 1454. The threonine at codon 485 is replaced by lysine, an amino acid with similar properties. 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	0.094
BayesDel_addAF	Benign	-0.18	T
BayesDel_noAF	Benign	-0.50
Cadd	Benign	15
Dann	Benign	0.87
DEOGEN2	Benign	0.050	T;T
Eigen	Benign	-0.76
Eigen_PC	Benign	-0.54
FATHMM_MKL	Benign	0.41	N
LIST_S2	Benign	0.44	T;T
M_CAP	Benign	0.0097	T
MetaRNN	Benign	0.056	T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	0.34	N;.
MutationTaster	Benign	1.0	N;N
PrimateAI	Benign	0.45	T
PROVEAN	Benign	0.43	N;N
REVEL	Benign	0.0090
Sift	Benign	0.72	T;T
Sift4G	Benign	0.94	T;T
Polyphen		0.0010	B;.
Vest4		0.16
MutPred		0.22		Gain of ubiquitination at T485 (P = 0.0045);.;
MVP		0.57
MPC		0.080
ClinPred		0.034	T
GERP RS		3.0
Varity_R		0.018
gMVP		0.16

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs200891292; hg19: chr8-90965863;