8-89943339-G-T

Position:

• chr8-89943339-G-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.2098C>A​(p.Pro700Thr) variant causes a missense change. The variant allele was found at a frequency of 0.000000687 in 1,456,346 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 Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P700L) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: NBN NM_002485.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: 6.60

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, 0.877

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NBN	NM_002485.5	c.2098C>A	p.Pro700Thr	missense_variant	14/16	ENST00000265433.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NBN	ENST00000265433.8	c.2098C>A	p.Pro700Thr	missense_variant	14/16	1	NM_002485.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251288 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135804

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.87e-7 AC: 1 AN: 1456346 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 724928

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

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	Dec 08, 2021	This variant is present in population databases (no rsID available, gnomAD 0.003%). 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 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"). ClinVar contains an entry for this variant (Variation ID: 411748). This variant has not been reported in the literature in individuals affected with NBN-related conditions. This sequence change replaces proline, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 700 of the NBN protein (p.Pro700Thr). -
Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Genetic Services Laboratory, University of Chicago

Sep 28, 2020

DNA sequence analysis of the NBN gene demonstrated a sequence change, c.2098C>A, in exon 14 that results in an amino acid change, p.Pro700Thr. This sequence change does not appear to have been previously described in patients with NBN-related disorders and has been described in the gnomAD database in one individual with an overall population frequency of 0.0004% (dbSNP rs1060503461). The p.Pro700Thr change affects a highly conserved amino acid residue located in a domain of the NBN protein that is known to be functional. The p.Pro700Thr substitution appears to be deleterious using several in-silico pathogenicity prediction tools (SIFT, PolyPhen2, Align GVGD, REVEL). Due to the lack of functional studies, the clinical significance of the p.Pro700Thr change remains unknown at this time. -

Aplastic anemia Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Baylor Genetics

Jan 08, 2024

- -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 05, 2024

The p.P700T variant (also known as c.2098C>A), located in coding exon 14 of the NBN gene, results from a C to A substitution at nucleotide position 2098. The proline at codon 700 is replaced by threonine, an amino acid with highly similar properties. 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	Pathogenic	0.84
BayesDel_addAF	Pathogenic	0.28	D
BayesDel_noAF	Pathogenic	0.24
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.58	D;T;.
Eigen	Pathogenic	0.84
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Uncertain	0.93	D;D;D
M_CAP	Benign	0.063	D
MetaRNN	Pathogenic	0.88	D;D;D
MetaSVM	Uncertain	0.20	D
MutationAssessor	Uncertain	2.6	M;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.65	T
PROVEAN	Pathogenic	-5.6	D;D;.
REVEL	Pathogenic	0.70
Sift	Uncertain	0.0030	D;D;.
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;.;.
Vest4		0.82
MutPred		0.70		Gain of loop (P = 0.0013);.;.;
MVP		0.95
MPC		0.43
ClinPred		0.98	D
GERP RS		5.9
Varity_R		0.68
gMVP		0.52

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: rs1060503461; hg19: chr8-90955567;