8-89943254-T-A

Position:

• chr8-89943254-T-A

Variant summary

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

The NM_002485.5(NBN):​c.2183A>T​(p.Glu728Val) variant causes a missense, splice region change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: NBN NM_002485.5 missense, splice_region
• Scores: Splicing: ADA: 0.9998
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.28

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: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NBN	NM_002485.5	c.2183A>T	p.Glu728Val	missense_variant, splice_region_variant	14/16	ENST00000265433.8	NP_002476.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
NBN	ENST00000265433.8	c.2183A>T	p.Glu728Val	missense_variant, splice_region_variant	14/16	1	NM_002485.5	ENSP00000265433	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Apr 24, 2023

This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glutamic acid, which is acidic and polar, with valine, which is neutral and non-polar, at codon 728 of the NBN protein (p.Glu728Val). This variant has not been reported in the literature in individuals affected with NBN-related conditions. 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 sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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. ClinVar contains an entry for this variant (Variation ID: 411785). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.40
BayesDel_addAF	Uncertain	0.13	D
BayesDel_noAF	Uncertain	-0.050
CADD	Pathogenic	28
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.51	D;T;.
Eigen	Pathogenic	0.72
Eigen_PC	Pathogenic	0.70
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Uncertain	0.86	D;T;T
M_CAP	Uncertain	0.19	D
MetaRNN	Pathogenic	0.87	D;D;D
MetaSVM	Uncertain	-0.033	T
MutationAssessor	Uncertain	2.5	M;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.49	T
PROVEAN	Pathogenic	-4.7	D;D;.
REVEL	Uncertain	0.60
Sift	Pathogenic	0.0	D;D;.
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;.;.
Vest4		0.61
MutPred		0.74		Loss of disorder (P = 0.004);.;.;
MVP		0.88
MPC		0.44
ClinPred		1.0	D
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.77
gMVP		0.47

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.98
SpliceAI score (max)		0.58		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.58		Position offset: -1

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

Publications

LitVar

Other links and lift over

dbSNP: rs1060503487; hg19: chr8-90955482;