8-89971195-A-G

Variant names:

• chr8-89971195-A-G
• rs749025721
• NM_002485.5:c.680T>C

Variant summary

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

The NM_002485.5(NBN):​c.680T>C​(p.Phe227Ser) variant causes a missense change. The variant allele was found at a frequency of 0.000000685 in 1,460,668 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 (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: NBN NM_002485.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 7.08

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, 0.849

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NBN	NM_002485.5	c.680T>C	p.Phe227Ser	missense_variant	Exon 6 of 16	ENST00000265433.8	NP_002476.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NBN	ENST00000265433.8	c.680T>C	p.Phe227Ser	missense_variant	Exon 6 of 16	1	NM_002485.5	ENSP00000265433.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250480 Hom.: 0 AF XY: 0.00000738 AC XY: 1 AN XY: 135434

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

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: 0.00000884

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460668 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 726634

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: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency Uncertain:2

Nov 07, 2021

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 08, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. This sequence change replaces phenylalanine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 227 of the NBN protein (p.Phe227Ser). This variant is present in population databases (rs749025721, 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: 419540). 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"). -

not provided Uncertain:1

Jul 22, 2015

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is denoted NBN c.680T>C at the cDNA level, p.Phe227Ser (F227S) at the protein level, and results in the change of a Phenylalanine to a Serine (TTT>TCT). This variant was observed in a cohort of individuals referred for hereditary cancer testing (Yorczyk 2014). NBN Phe227Ser 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 Phenylalanine and Serine differ in polarity, charge, size or other properties, this is considered a non-conservative amino acid substitution. NBN Phe227Ser occurs at a position that is conserved across species and is located in the region of interaction with MTOR, MAPKAP1 and RICTOR and the region that mediates interaction with SP100 (UniProt). In silico analyses predict that this variant is probably damaging to protein structure and function. Based on currently available information, it is unclear whether NBN Phe227Ser is pathogenic or benign. We consider it to be a variant of uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.45	D
BayesDel_noAF	Pathogenic	0.41
CADD	Uncertain	26
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.56	D;T;.;.
Eigen	Pathogenic	0.86
Eigen_PC	Pathogenic	0.82
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.91	D;T;D;D
M_CAP	Pathogenic	0.29	D
MetaRNN	Pathogenic	0.85	D;D;D;D
MetaSVM	Uncertain	0.68	D
MutationAssessor	Pathogenic	3.0	M;.;.;.
PrimateAI	Uncertain	0.65	T
PROVEAN	Pathogenic	-6.7	D;D;D;D
REVEL	Pathogenic	0.87
Sift	Pathogenic	0.0	D;D;T;D
Sift4G	Pathogenic	0.0	D;D;D;.
Polyphen		1.0	D;.;.;.
Vest4		0.99
MutPred		0.58		Loss of helix (P = 0.0068);.;.;.;
MVP		0.96
MPC		0.53
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.93
gMVP		0.92

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: rs749025721; hg19: chr8-90983423;