chr8-89981406-T-C

Position:

• chr8-89981406-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2 BP4

The NM_002485.5(NBN):​c.289A>G​(p.Ile97Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,760 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: NBN NM_002485.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:1
• Conservation: PhyloP100: 0.523

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 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.35118717).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NBN	NM_002485.5	c.289A>G	p.Ile97Val	missense_variant	3/16	ENST00000265433.8	NP_002476.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
NBN	ENST00000265433.8	c.289A>G	p.Ile97Val	missense_variant	3/16	1	NM_002485.5	ENSP00000265433.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461760 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727168

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency Uncertain:2

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	Jun 11, 2022	Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Tolerated"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The valine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. 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. ClinVar contains an entry for this variant (Variation ID: 182726). This variant has not been reported in the literature in individuals affected with NBN-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces isoleucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 97 of the NBN protein (p.Ile97Val). -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Apr 22, 2014

This variant is denoted NBN c.289A>G at the cDNA level, p.Ile97Val (I97V) at the protein level, and results in the change of an Isoleucine to a Valine (ATT>GTT). This variant has not, to our knowledge, been published in the literature as pathogenic or benign. NBN Ile97Val was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. Since Isoleucine and Valine share similar properties, this is considered a conservative amino acid substitution. NBN Ile97Val occurs at a position that is highly variable across many species and is not located in a known functional domain. In silico analyses predict that this variant is unlikely to alter protein structure or function. Based on currently available information, it is unclear whether NBN Ile97Val is pathogenic or benign. We consider it to be a variant of uncertain significance. Furthermore, NBN has been only recently described in association with cancer predisposition and the risks are not well understood. -

Hereditary cancer-predisposing syndrome Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Oct 07, 2021

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.087
BayesDel_addAF	Benign	-0.15	T
BayesDel_noAF	Benign	-0.45
CADD	Benign	7.1
DANN	Benign	0.21
DEOGEN2	Benign	0.22	T;T;.;.;.
Eigen	Benign	-0.81
Eigen_PC	Benign	-0.64
FATHMM_MKL	Benign	0.17	N
LIST_S2	Benign	0.76	T;T;T;T;T
M_CAP	Benign	0.023	T
MetaRNN	Benign	0.35	T;T;T;T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	0.14	N;.;.;.;.
PrimateAI	Benign	0.28	T
PROVEAN	Benign	0.19	N;N;N;N;N
REVEL	Benign	0.14
Sift	Benign	1.0	T;T;T;T;T
Sift4G	Benign	1.0	T;T;T;.;T
Polyphen		0.0030	B;.;.;.;.
Vest4		0.099
MutPred		0.84		Gain of ubiquitination at K92 (P = 0.1235);.;Gain of ubiquitination at K92 (P = 0.1235);.;.;
MVP		0.60
MPC		0.060
ClinPred		0.062	T
GERP RS		1.8
Varity_R		0.024
gMVP		0.28

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: rs730881855; hg19: chr8-90993634;