rs1554556582

chr8-89946264-A-Gchr8-89946264-A-T

Variant summary

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

The NM_002485.5(NBN):c.1946T>C(p.Met649Thr) 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. 15/20 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. M649I) has been classified 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: 0.00800

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 -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.05786422).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NBN	NM_002485.5	c.1946T>C	p.Met649Thr	missense_variant	13/16	ENST00000265433.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NBN	ENST00000265433.8	c.1946T>C	p.Met649Thr	missense_variant	13/16	1	NM_002485.5	P1

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	Invitae	Sep 14, 2023	This sequence change replaces methionine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 649 of the NBN protein (p.Met649Thr). 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: 496667). 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 tolerated. 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	- -

Malignant tumor of breast Uncertain:1

Uncertain significance, criteria provided, single submitter

research

CSER _CC_NCGL, University of Washington

Oct 01, 2016

Found in patient having exome sequencing due to suspicion for hereditary colon cancer and/or polyps. Patient is a 50 year old female diagnosed with colon cancer at age 49. This interpretation considers GERP score and allele frequency data, in addition to published reports of the variant in the literature, available at the time of review. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 16, 2022

The p.M649T variant (also known as c.1946T>C), located in coding exon 13 of the NBN gene, results from a T to C substitution at nucleotide position 1946. The methionine at codon 649 is replaced by threonine, 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	0.11
BayesDel_addAF	Benign	-0.19	T
BayesDel_noAF	Benign	-0.50
Cadd	Benign	9.6
Dann	Benign	0.69
DEOGEN2	Benign	0.18	T;T
Eigen	Benign	-0.73
Eigen_PC	Benign	-0.62
FATHMM_MKL	Benign	0.22	N
LIST_S2	Benign	0.30	T;T
M_CAP	Benign	0.0085	T
MetaRNN	Benign	0.058	T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	1.7	L;.
MutationTaster	Benign	1.0	N;N
PrimateAI	Benign	0.36	T
PROVEAN	Benign	-0.57	N;N
REVEL	Benign	0.028
Sift	Benign	0.57	T;T
Sift4G	Benign	0.56	T;T
Polyphen		0.050	B;.
Vest4		0.24
MutPred		0.18		Gain of loop (P = 3e-04);.;
MVP		0.63
MPC		0.086
ClinPred		0.048	T
GERP RS		0.016
Varity_R		0.027
gMVP		0.14

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: rs1554556582; hg19: chr8-90958492;