Genetic Variant NBN:p.Ala127Ala (chr8-89980833-A-C) – ACMG Classification: Likely_benign (-3 pts)

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2BP4_StrongBP7

The NM_002485.5(NBN):c.381T>G(p.Ala127Ala) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,460,358 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. A127A) has been classified as Likely benign.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

NBN
NM_002485.5 synonymous

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 1.43

Publications

0 publications found

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 Gene-Disease associations (from GenCC):

Nijmegen breakage syndrome
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Labcorp Genetics (formerly Invitae), ClinGen, Myriad Women’s Health
rhabdomyosarcoma
Inheritance: AR Classification: MODERATE Submitted by: Genomics England PanelApp
idiopathic aplastic anemia
Inheritance: AD Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)
prostate cancer
Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
hereditary breast carcinoma
Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

NBN links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -3 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.61).

BP7

Synonymous conserved (PhyloP=1.43 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NBN	NM_002485.5 link	c.381T>G	p.Ala127Ala	synonymous_variant	Exon 4 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.381T>G	p.Ala127Ala	synonymous_variant	Exon 4 of 16	1	NM_002485.5	ENSP00000265433.4		O60934

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.85e-7

AC:

AN:

1460358

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

726610

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33436

American (AMR)

AF:

0.00

AC:

AN:

44718

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26122

East Asian (EAS)

AF:

0.00

AC:

AN:

39612

South Asian (SAS)

AF:

0.00

AC:

AN:

86232

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53236

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5758

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1110882

Other (OTH)

AF:

0.0000166

AC:

AN:

60362

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.325

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.61

CADD

Benign

(source)

DANN

Benign

0.76

PhyloP100

1.4

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.050

Details are displayed if max score is > 0.2

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over