rs147494981

Positions:

• chr8-89937040-A-G

Variant summary

Our verdict is Benign. Variant got -15 ACMG points: 0P and 15B. BP4_Moderate BP6_Very_Strong BP7 BS1

The NM_002485.5(NBN):​c.2220T>C​(p.Ala740=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000159 in 1,611,442 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.00025 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00015 (0 hom.)
• Consequence: NBN NM_002485.5 synonymous
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:8
• Conservation: PhyloP100: 0.941

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 Benign. Variant got -15 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.43).
• BP6: Variant 8-89937040-A-G is Benign according to our data. Variant chr8-89937040-A-G is described in ClinVar as [Likely_benign]. Clinvar id is 136043.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr8-89937040-A-G is described in Lovd as [Benign].
• BP7: Synonymous conserved (PhyloP=0.941 with no splicing effect.
• BS1: Variant frequency is greater than expected in population eas. gnomad4 allele frequency = 0.000249 (38/152368) while in subpopulation EAS AF= 0.00694 (36/5188). AF 95% confidence interval is 0.00515. There are 0 homozygotes in gnomad4. There are 25 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NBN	NM_002485.5	c.2220T>C	p.Ala740=	synonymous_variant	15/16	ENST00000265433.8	NP_002476.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
NBN	ENST00000265433.8	c.2220T>C	p.Ala740=	synonymous_variant	15/16	1	NM_002485.5	ENSP00000265433	P1

Frequencies

GnomAD3 genomes AF: 0.000250 AC: 38 AN: 152250 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00692

Gnomad SAS AF: 0.000414

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000556 AC: 139 AN: 250016 Hom.: 0 AF XY: 0.000451 AC XY: 61 AN XY: 135150

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00751

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000164

GnomAD4 exome AF: 0.000149 AC: 218 AN: 1459074 Hom.: 0 Cov.: 29 AF XY: 0.000139 AC XY: 101 AN XY: 725974

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00500

Gnomad4 SAS exome AF: 0.0000812

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.01e-7

Gnomad4 OTH exome AF: 0.000199

GnomAD4 genome AF: 0.000249 AC: 38 AN: 152368 Hom.: 0 Cov.: 32 AF XY: 0.000336 AC XY: 25 AN XY: 74510

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00694

Gnomad4 SAS AF: 0.000414

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000133 Hom.: 0

Bravo AF: 0.000280

Asia WGS AF: 0.00145 AC: 5 AN: 3474

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:8

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:3

Benign, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Aug 09, 2020	- -
Benign, criteria provided, single submitter	clinical testing	GeneDx	Aug 18, 2014	This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -
Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Feb 14, 2019	Variant summary: NBN c.2220T>C alters a non-conserved nucleotide resulting in a synonymous change. 5/5 computational tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 0.00056 in 281422 control chromosomes, predominantly within the East Asian subpopulation at a frequency of 0.0078 in the gnomAD database. The observed variant frequency within East Asian control individuals in the gnomAD database is approximately 60 fold of the estimated maximal expected allele frequency for a pathogenic variant in NBN causing Hereditary Breast and Ovarian Cancer phenotype, strongly suggesting that the variant is a benign polymorphism found primarily in populations of East Asian origin. Though the variant, c.2220T>C, has been reported in the literature in East Asian individuals affected with breast cancer (Kim 2015), it was also found in several healthy controls (Momozawa 2018). A large case-control association study involving unselected breast cancer patients and controls of Japanese ancestry concluded that the variant is benign (Momozawa 2018). To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Two clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation and classified the variant as benign (1x) / likely benign (1x). Based on the evidence outlined above, the variant was classified as benign. -

Microcephaly, normal intelligence and immunodeficiency Benign:2

Benign, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 31, 2024	- -
Likely benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 12, 2018	This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Hereditary cancer-predisposing syndrome Benign:2

Benign, criteria provided, single submitter	curation	Sema4, Sema4	Aug 16, 2021	- -
Likely benign, criteria provided, single submitter	clinical testing	Ambry Genetics	Oct 17, 2014	This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Malignant tumor of breast Benign:1

Likely benign, no assertion criteria provided

clinical testing

Department of Pathology and Laboratory Medicine, Sinai Health System

-

The NBN p.Ala740= variant was identified in 47 of 14,208 proband chromosomes (frequency: 0.003) from individuals with breast cancer and was present in 117 of 47,460 control chromosomes (frequency: 0.002) from healthy individuals (Momozawa 2018). The variant was identified in dbSNP (rs147494981) as “with likely benign allele”, ClinVar (classified as benign by Invitae and GeneDx and likely benign by Color and Ambry Genetics) and LOVD 3.0 (observed 5x). The variant was identified in control databases in 157 of 281,422 chromosomes at a frequency of 0.0006 (Genome Aggregation Database Feb 27, 2017). The variant was observed in the following populations: East Asian in 156 of 19,936 chromosomes (freq: 0.008 increasing the likelihood this could be a low frequency benign variant), Other in 1 of 7180 chromosomes (freq: 0.0001), while the variant was not observed in the African, Latino, Ashkenazi Jewish, Finnish, European and South Asian populations. The p.Ala740= variant is not expected to have clinical significance because it does not result in a change of amino acid and is not located in a known consensus splice site. The variant occurs at a non-highly conserved nucleotide outside of the splicing consensus sequence and in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer) do not predict a difference in splicing. In summary, based on the above information the clinical significance of this variant cannot be determined with certainty at this time although we would lean towards a more benign role for this variant. This variant is classified as likely benign. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.43
CADD	Benign	8.7
DANN	Benign	0.67

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs147494981; hg19: chr8-90949268;