8-89981460-T-G

Position:

• chr8-89981460-T-G

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The ENST00000265433.8(NBN):​c.235A>C​(p.Asn79His) variant causes a missense change. The variant allele was found at a frequency of 0.00000205 in 1,461,578 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. N79D) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: NBN ENST00000265433.8 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 5.82

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.979

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NBN	NM_002485.5	c.235A>C	p.Asn79His	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.235A>C	p.Asn79His	missense_variant	3/16	1	NM_002485.5	ENSP00000265433	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461578 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727094

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:4

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	Labcorp Genetics (formerly Invitae), Labcorp	Jul 19, 2021	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 do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with NBN-related disease. ClinVar contains an entry for this variant (Variation ID: 421316). This variant is not present in population databases (ExAC no frequency). This sequence change replaces asparagine with histidine at codon 79 of the NBN protein (p.Asn79His). The asparagine residue is moderately conserved and there is a small physicochemical difference between asparagine and histidine. -
Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

May 27, 2016

This variant is denoted NBN c.235A>C at the cDNA level, p.Asn79His (N79H) at the protein level, and results in the change of an Asparagine to a Histidine (AAT>CAT). This variant has not, to our knowledge, been published in the literature as pathogenic or benign. NBN Asn79His was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, suggesting it is not a common benign variant in these populations. Since Asparagine and Histidine differ in some properties, this is considered a semi-conservative amino acid substitution. NBN Asn79His occurs at a position that is conserved across species and is located in the FHA domain (UniProt). In silico analyses predict that this variant is probably damaging to protein structure and function. Based on currently available evidence, it is unclear whether NBN Asn79His is a pathogenic or benign variant. We consider it to be a variant of uncertain significance. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jul 08, 2019

The p.N79H variant (also known as c.235A>C), located in coding exon 3 of the NBN gene, results from an A to C substitution at nucleotide position 235. The asparagine at codon 79 is replaced by histidine, an amino acid with similar properties. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.47
BayesDel_addAF	Uncertain	0.069	T
BayesDel_noAF	Benign	-0.14
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.72	D;.
Eigen	Pathogenic	0.92
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.91	D;D
M_CAP	Uncertain	0.086	D
MetaRNN	Pathogenic	0.98	D;D
MetaSVM	Uncertain	0.35	D
MutationAssessor	Pathogenic	4.6	H;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.52	T
PROVEAN	Uncertain	-4.0	D;D
REVEL	Uncertain	0.62
Sift	Uncertain	0.0030	D;D
Sift4G	Uncertain	0.0040	D;D
Polyphen		1.0	D;.
Vest4		0.79
MutPred		0.92		Gain of catalytic residue at N79 (P = 0.1138);Gain of catalytic residue at N79 (P = 0.1138);
MVP		0.87
MPC		0.40
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.85
gMVP		0.68

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs786202749; hg19: chr8-90993688;