rs1554567892

Positions:

• chr8-89980768-TG-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_002485.5(NBN):​c.445delC​(p.His149fs) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,164 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: NBN NM_002485.5 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 7.55

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 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 8-89980768-TG-T is Pathogenic according to our data. Variant chr8-89980768-TG-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 480026.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
NBN	NM_002485.5	c.445delC	p.His149fs	frameshift_variant	4/16	ENST00000265433.8	NP_002476.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
NBN	ENST00000265433.8	c.445delC	p.His149fs	frameshift_variant	4/16	1	NM_002485.5	ENSP00000265433.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461164 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 726940

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jun 23, 2023	This variant is not present in population databases (gnomAD no frequency). For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 480026). This variant has not been reported in the literature in individuals affected with NBN-related conditions. This sequence change creates a premature translational stop signal (p.His149Thrfs*7) in the NBN gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in NBN are known to be pathogenic (PMID: 9590180, 16415040). -
Pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Nov 07, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Apr 05, 2023	Variant summary: NBN c.445delC (p.His149ThrfsX7) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. The variant was absent in 251268 control chromosomes. To our knowledge, no occurrence of c.445delC in individuals affected with Nijmegen Breakage Syndrome and no experimental evidence demonstrating its impact on protein function have been reported. Four clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and classified it as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Aplastic anemia Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Baylor Genetics

Sep 24, 2023

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Quest Diagnostics Nichols Institute San Juan Capistrano

Feb 05, 2019

The variant results in a shift of the reading frame, and is therefore predicted to result in the loss of a functional protein. Found in at least one symptomatic patient, and not found in general population data. -

Hereditary cancer-predisposing syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 16, 2023

The c.445delC pathogenic mutation, located in coding exon 4 of the NBN gene, results from a deletion of one nucleotide at nucleotide position 445, causing a translational frameshift with a predicted alternate stop codon (p.H149Tfs*7). This alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. As such, this alteration is interpreted as a disease-causing mutation. -

Computational scores

Source: dbNSFP v4.3

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: rs1554567892; hg19: chr8-90992996;