rs771034958

chr8-89980874-C-Achr8-89980874-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_002485.5(NBN):c.340G>T(p.Val114Phe) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,460,496 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V114I) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: NBN NM_002485.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:8
• Conservation: PhyloP100: 1.81

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 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.855

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NBN	NM_002485.5	c.340G>T	p.Val114Phe	missense_variant	4/16	ENST00000265433.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NBN	ENST00000265433.8	c.340G>T	p.Val114Phe	missense_variant	4/16	1	NM_002485.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1460496 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 726616

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: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:8

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency Uncertain:4

Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Oct 24, 2017	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Jan 20, 2024	This sequence change replaces valine, which is neutral and non-polar, with phenylalanine, which is neutral and non-polar, at codon 114 of the NBN protein (p.Val114Phe). RNA analysis indicates that this missense change induces altered splicing and may result in an absent or disrupted protein product. This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with personal and family history of breast cancer, uterine cancer and ovarian cancer (PMID: 28202063). ClinVar contains an entry for this variant (Variation ID: 219644). 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 disruptive. Studies have shown that this missense change results in activation of a cryptic splice site and introduces a premature termination codon (Invitae). The resulting mRNA is expected to undergo nonsense-mediated decay. 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.	Sep 28, 2020	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -

Aplastic anemia Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Baylor Genetics

Oct 18, 2023

- -

Aplastic anemia;C0023449:Acute lymphoid leukemia;C0398791:Microcephaly, normal intelligence and immunodeficiency Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

Oct 31, 2018

- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Quest Diagnostics Nichols Institute San Juan Capistrano

Jul 21, 2017

- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Sep 09, 2022

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Identified in individuals with breast cancer, but also in unaffected controls (Jalkh et al., 2017; Momozawa et al., 2018); This variant is associated with the following publications: (PMID: 28202063, 24894818, 30287823) -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 09, 2023

The p.V114F variant (also known as c.340G>T), located in coding exon 4 of the NBN gene, results from a G to T substitution at nucleotide position 340. The valine at codon 114 is replaced by phenylalanine, an amino acid with highly similar properties. This alteration was not observed in 7,051 unselected female breast cancer patients and was observed with an allele frequency of 0.00009 in 11,241 female controls of Japanese ancestry (Momozawa Y et al. Nat Commun, 2018 10;9:4083). This alteration was also detected in 1/45 Lebanese patients with reported family history of breast cancer who were tested with whole-exome sequencing (Jalkh N et al. BMC Med Genomics, 2017 02;10:8). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious 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	0.29
BayesDel_addAF	Pathogenic	0.26	D
BayesDel_noAF	Pathogenic	0.14
Cadd	Uncertain	24
Dann	Uncertain	0.99
DEOGEN2	Uncertain	0.58	D;T;.;.
Eigen	Uncertain	0.65
Eigen_PC	Uncertain	0.62
FATHMM_MKL	Uncertain	0.76	D
LIST_S2	Uncertain	0.92	D;D;D;D
M_CAP	Benign	0.051	D
MetaRNN	Pathogenic	0.86	D;D;D;D
MetaSVM	Benign	-0.51	T
MutationAssessor	Uncertain	2.8	M;.;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Benign	0.43	T
PROVEAN	Uncertain	-4.2	D;D;D;D
REVEL	Uncertain	0.47
Sift	Uncertain	0.0010	D;D;D;D
Sift4G	Uncertain	0.0020	D;D;.;D
Polyphen		1.0	D;.;.;.
Vest4		0.89
MutPred		0.75		Gain of catalytic residue at P112 (P = 0.1677);.;.;.;
MVP		0.77
MPC		0.45
ClinPred		0.99	D
GERP RS		4.9
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.75
gMVP		0.82

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.46		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.46		Position offset: 19

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs771034958; hg19: chr8-90993102;