Genetic Variant NBN:p.Gly75Ala (chr8-89981471-C-G) – ACMG Classification: Uncertain_significance (2 pts)

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PP3_Moderate

The NM_002485.5(NBN):c.224G>C(p.Gly75Ala) variant causes a missense change. The variant allele was found at a frequency of 0.0000366 in 1,613,338 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: 𝑓 0.000026 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000038 ( 0 hom. )

Consequence

NBN
NM_002485.5 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:10

Conservation

PhyloP100: 5.74

Variant links:

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]

NBN links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 2 ACMG points.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.895

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NBN	NM_002485.5 link	c.224G>C	p.Gly75Ala	missense_variant	Exon 3 of 16	ENST00000265433.8	NP_002476.2	O60934

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NBN	ENST00000265433.8 link	c.224G>C	p.Gly75Ala	missense_variant	Exon 3 of 16	1	NM_002485.5	ENSP00000265433.4		O60934

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

152174

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000483

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000654

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000796

AC:

AN:

251334

Hom.:

AF XY:

0.00000736

AC XY:

AN XY:

135850

show subpopulations

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:

0.0000176

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000376

AC:

AN:

1461164

Hom.:

Cov.:

AF XY:

0.0000316

AC XY:

AN XY:

726940

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

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:

0.0000468

Gnomad4 OTH exome

AF:

0.0000331

GnomAD4 genome

AF:

0.0000263

AC:

AN:

152174

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74336

show subpopulations

Gnomad4 AFR

AF:

0.0000483

Gnomad4 AMR

AF:

0.0000654

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000565

Hom.:

Bravo

AF:

0.0000378

ExAC

AF:

0.00000824

AC:

EpiCase

AF:

0.00

EpiControl

AF:

0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:10

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency

Uncertain:5

Aug 19, 2021

St. Jude Molecular Pathology, St. Jude Children's Research Hospital

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The NBN c.224G>C (p.Gly75Ala) missense change has a maximum subpopulation frequency of 0.0018% in gnomAD v2.1.1 (PM2_supporting; https://gnomad.broadinstitute.org/variant/8-90993699-C-G). Six of seven in silico tools predict a deleterious effect of this variant on protein function (PP3), but to our knowledge these predictions have not been confirmed by functional assays. This variant has been reported in an individual diagnosed with mismatch repair proficient sigmoid colon cancer at age 30 (PMID: 27978560). It is also present 1x in the FLOSSIES database which contains genetic variants from women older than 70 years of age who have never had cancer (https://whi.color.com/variant/8-90993699-C-G). To our knowledge, this variant has not been reported in individuals with Nijmegan breakage syndrome or breast cancer. In summary, this variant meets criteria to be classified as of uncertain significance based on the ACMG/AMP criteria: PM2_supporting, PP3. -

Nov 07, 2021

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

May 04, 2017

Counsyl

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Sep 23, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine, which is neutral and non-polar, with alanine, which is neutral and non-polar, at codon 75 of the NBN protein (p.Gly75Ala). This variant is present in population databases (rs587782179, gnomAD 0.002%). 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: 142014). 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. 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. -

Sep 16, 2020

Natera, Inc.

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Hereditary cancer-predisposing syndrome

Uncertain:2

Jun 10, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.G75A variant (also known as c.224G>C), located in coding exon 3 of the NBN gene, results from a G to C substitution at nucleotide position 224. The glycine at codon 75 is replaced by alanine, an amino acid with similar properties. This alteration has been previously identified in an individual from a North American cohort of individuals with early onset colon cancer (Pearlman R et al. JAMA Oncol, 2017 Apr;3:464-471). Additionally, this variant was reported in 3/60,466 breast cancer cases and in 2/53,461 controls (Dorling et al. N Engl J Med. 2021 02;384:428-439). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Mar 05, 2022

Sema4, Sema4

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: curation

- -

not specified

Uncertain:1

Sep 26, 2022

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

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: NBN c.224G>C (p.Gly75Ala) results in a non-conservative amino acid change located in the Forkhead-associated (FHA) domain (IPR000253) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 8e-06 in 251334 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.224G>C has been reported in the literature in at-least one individual affected with MMR proficient sigmoid colon cancer (Pearlman_2016). This report does not provide unequivocal conclusions about association of the variant with Nijmegen Breakage Syndrome. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Nine clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and all classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Aplastic anemia

Uncertain:1

Mar 10, 2024

Baylor Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided

Uncertain:1

Aug 17, 2024

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Observed in an individual with MMR-proficient colorectal cancer, as well as cases and controls in a breast cancer study (PMID: 27978560, 33471991); This variant is associated with the following publications: (PMID: 28569743, 33471991, 24894818, 27978560, 36346689) -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.86

BayesDel_addAF

Pathogenic

0.38

BayesDel_noAF

Pathogenic

0.32

CADD

Pathogenic

DANN

Uncertain

1.0

DEOGEN2

Uncertain

0.70

D;.

Eigen

Pathogenic

0.99

Eigen_PC

Pathogenic

0.91

FATHMM_MKL

Uncertain

0.94

LIST_S2

Uncertain

0.95

D;D

M_CAP

Uncertain

0.12

MetaRNN

Pathogenic

0.90

D;D

MetaSVM

Uncertain

0.63

MutationAssessor

Pathogenic

4.2

H;.

PrimateAI

Uncertain

0.64

PROVEAN

Pathogenic

-5.4

D;D

REVEL

Pathogenic

0.78

Sift

Pathogenic

0.0

D;D

Sift4G

Pathogenic

0.0

D;D

Polyphen

1.0

D;.

Vest4

0.94

MVP

0.92

MPC

0.42

ClinPred

1.0

GERP RS

5.8

Varity_R

0.95

gMVP

0.86

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over