rs786203131

Positions:

• chr8-89955367-C-A
• chr8-89955367-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_002485.5(NBN):​c.1313G>T​(p.Ser438Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,590 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. S438G) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: NBN NM_002485.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: -0.152

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 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.07489321).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NBN	NM_002485.5	c.1313G>T	p.Ser438Ile	missense_variant	10/16	ENST00000265433.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NBN	ENST00000265433.8	c.1313G>T	p.Ser438Ile	missense_variant	10/16	1	NM_002485.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461590 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727098

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: 0.00000270

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:3

Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Nov 13, 2023	This sequence change replaces serine, which is neutral and polar, with isoleucine, which is neutral and non-polar, at codon 438 of the NBN protein (p.Ser438Ile). This variant is present in population databases (rs786203131, gnomAD 0.0009%). 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: 186671). 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, no assertion criteria provided	clinical testing	Natera, Inc.	Jul 02, 2020	- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Sep 28, 2017

Variant summary: The NBN c.1313G>T (p.Ser438Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide located in the BRCT domain(IPR001357) (InterPro). 2/4 in silico tools predict a benign outcome for this variant (SNPsandGO not captured due to low reliability index). This variant was found in 1/246062 control chromosomes (gnomAD) at a frequency of 0.0000041, which does not exceed the estimated maximal expected allele frequency of a pathogenic NBN variant (0.000125). In addition, multiple clinical diagnostic laboratories in ClinVar have classified this variant as uncertain significance. The variant of interest has not, to our knowledge, been reported in affected individuals via publications, nor has it been evaluated for functional impact by in vivo/vitro studies. Because of the absence of clinical information and the lack of functional studies, the variant is classified as a variant of uncertain significance (VUS) until additional information becomes available. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jan 31, 2022

The p.S438I variant (also known as c.1313G>T), located in coding exon 10 of the NBN gene, results from a G to T substitution at nucleotide position 1313. The serine at codon 438 is replaced by isoleucine, an amino acid with dissimilar 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	0.087
BayesDel_addAF	Benign	-0.21	T
BayesDel_noAF	Benign	-0.54
CADD	Benign	5.7
DANN	Benign	0.59
DEOGEN2	Benign	0.12	T;T
Eigen	Benign	-1.2
Eigen_PC	Benign	-1.3
FATHMM_MKL	Benign	0.031	N
LIST_S2	Benign	0.64	T;T
M_CAP	Benign	0.014	T
MetaRNN	Benign	0.075	T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	1.2	L;.
MutationTaster	Benign	1.0	N;N
PrimateAI	Benign	0.23	T
PROVEAN	Benign	-1.5	N;N
REVEL	Benign	0.026
Sift	Benign	0.048	D;D
Sift4G	Benign	0.12	T;T
Polyphen		0.14	B;.
Vest4		0.16
MutPred		0.24		Gain of methylation at K441 (P = 0.0377);.;
MVP		0.42
MPC		0.087
ClinPred		0.047	T
GERP RS		-1.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.033
gMVP		0.21

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: rs786203131; hg19: chr8-90967595;