8-89946142-T-G

Position:

• chr8-89946142-T-G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_002485.5(NBN):​c.2068A>C​(p.Lys690Gln) variant causes a missense, splice region change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: NBN NM_002485.5 missense, splice_region
• Scores: Splicing: ADA: 0.5069
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:7
• Conservation: PhyloP100: 3.69

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 Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.824

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NBN	NM_002485.5	c.2068A>C	p.Lys690Gln	missense_variant, splice_region_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.2068A>C	p.Lys690Gln	missense_variant, splice_region_variant	13/16	1	NM_002485.5	ENSP00000265433	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 28

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:7

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 29, 2022	This sequence change replaces lysine, which is basic and polar, with glutamine, which is neutral and polar, at codon 690 of the NBN protein (p.Lys690Gln). 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: 127864). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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 03, 2020	- -

Hereditary cancer-predisposing syndrome Uncertain:2

Uncertain significance, criteria provided, single submitter	curation	Sema4, Sema4	Jul 22, 2021	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	Jun 13, 2024	The p.K690Q variant (also known as c.2068A>C), located in coding exon 13 of the NBN gene, results from an A to C substitution at nucleotide position 2068. The lysine at codon 690 is replaced by glutamine, an amino acid with similar properties. This variant was reported in 0/60,466 breast cancer cases and in 1/53,461 controls (Dorling et al. N Engl J Med. 2021 02;384:428-439). This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Aplastic anemia Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Baylor Genetics

Aug 04, 2023

- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Apr 01, 2021

Not observed in large population cohorts (Lek 2016); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge; This variant is associated with the following publications: (PMID: 17612497) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.83
BayesDel_addAF	Uncertain	0.13	D
BayesDel_noAF	Uncertain	-0.050
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.56	D;T
Eigen	Uncertain	0.65
Eigen_PC	Uncertain	0.62
FATHMM_MKL	Uncertain	0.88	D
LIST_S2	Uncertain	0.91	D;D
M_CAP	Uncertain	0.14	D
MetaRNN	Pathogenic	0.82	D;D
MetaSVM	Uncertain	0.49	D
MutationAssessor	Uncertain	2.6	M;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.51	T
PROVEAN	Uncertain	-2.8	D;D
REVEL	Pathogenic	0.66
Sift	Uncertain	0.0040	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;.
Vest4		0.80
MutPred		0.61		Loss of helix (P = 0.0033);.;
MVP		0.94
MPC		0.42
ClinPred		0.99	D
GERP RS		5.2
Varity_R		0.50
gMVP		0.63

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.51
dbscSNV1_RF	Benign	0.69
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: rs587780092; hg19: chr8-90958370;