8-89943367-C-G

Variant names:

• chr8-89943367-C-G
• rs786201965
• NM_002485.5:c.2071-1G>C

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PVS1_Moderate PM2 PP5

The NM_002485.5(NBN):​c.2071-1G>C variant causes a splice acceptor, intron change. The variant allele was found at a frequency of 0.00000138 in 1,448,480 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: NBN NM_002485.5 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:8 U:1
• Conservation: PhyloP100: 5.17
• Publications: 3 publications found

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

ACMG classification

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.050331127 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 8-89943367-C-G is Pathogenic according to our data. Variant chr8-89943367-C-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 185152.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NBN	NM_002485.5	c.2071-1G>C		splice_acceptor_variant, intron_variant	Intron 13 of 15	ENST00000265433.8	NP_002476.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NBN	ENST00000265433.8	c.2071-1G>C		splice_acceptor_variant, intron_variant	Intron 13 of 15	1	NM_002485.5	ENSP00000265433.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000138 AC: 2 AN: 1448480 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 721460

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

African (AFR) AF: 0.00 AC: 0 AN: 33040

American (AMR) AF: 0.00 AC: 0 AN: 44700

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26044

East Asian (EAS) AF: 0.00 AC: 0 AN: 39570

South Asian (SAS) AF: 0.00 AC: 0 AN: 86002

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53284

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5746

European-Non Finnish (NFE) AF: 9.09e-7 AC: 1 AN: 1100158

Other (OTH) AF: 0.0000167 AC: 1 AN: 59936

⚠️ 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.

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:8 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Microcephaly, normal intelligence and immunodeficiency Pathogenic:3

Jan 28, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects an acceptor splice site in intron 13 of the NBN gene. RNA analysis indicates that disruption of this splice site induces altered splicing and likely results in a shortened protein product. This variant is not present in population databases (gnomAD no frequency). 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: 185152). Studies have shown that disruption of this splice site results in skipping of exon 14, but is expected to preserve the integrity of the reading-frame (internal data). In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Jan 18, 2016

Counsyl

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

Jul 31, 2020

Natera, Inc.

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

not provided Pathogenic:2 Uncertain:1

Jan 01, 2024

CeGaT Center for Human Genetics Tuebingen

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

NBN: PVS1:Strong, PM2 -

May 21, 2024

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Canonical splice site variant predicted to result in an in-frame loss of the adjacent exon in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 28152038, 24894818, 33471991, 26315354) -

May 10, 2024

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The NBN c.2071-1G>C variant disrupts a canonical splice-acceptor site and is predicted to interfere with normal NBN mRNA splicing. This variant has been reported in the published literature in individuals with breast cancer and reportedly healthy individuals (PMIDs: 33471991 (2021), 26315354 (2015), see also LOVD (http://databases.lovd.nl/shared/genes/NBN)). This variant has not been reported in large, multi-ethnic general populations (Genome Aggregation Database, http://gnomad.broadinstitute.org). Based on the available information, we are unable to determine the clinical significance of this variant. -

Aplastic anemia;C0023449:Acute lymphoid leukemia;C0398791:Microcephaly, normal intelligence and immunodeficiency Pathogenic:1

Apr 06, 2024

Fulgent Genetics, Fulgent Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Aplastic anemia Pathogenic:1

Dec 20, 2023

Baylor Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Hereditary cancer-predisposing syndrome Pathogenic:1

Apr 28, 2023

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2071-1G>C intronic variant results from a G to C substitution one nucleotide upstream from coding exon 14 of the NBN gene. This alteration was identified in an individual who underwent hereditary cancer multi-gene panel testing (LaDuca H et al. PLoS ONE, 2017 Feb;12:e0170843). This alteration was also observed in 0/3,236 cases with invasive epithelial ovarian cancer and 1/3,431 controls (Ramus SJ et al. J. Natl. Cancer Inst., 2015 Nov;107). This variant was also reported in 2/60,466 breast cancer cases and in 3/53,461 controls (Dorling et al. N Engl J Med. 2021 02;384:428-439). This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice acceptor site. RNA studies have demonstrated that this alteration results in abnormal splicing in the set of samples tested (Ambry internal data). Alterations that disrupt the canonical splice site are expected to cause aberrant splicing, resulting in an abnormal protein or a transcript that is subject to nonsense-mediated mRNA decay. As such, this alteration is classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.62	D
BayesDel_noAF	Pathogenic	0.33
CADD	Pathogenic	27
DANN	Uncertain	0.99
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	0.99	D
PhyloP100		5.2
GERP RS		5.6
Mutation Taster		=8/92	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_AL_spliceai		1.0		Position offset: -1

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

Other links and lift over

dbSNP: rs786201965; hg19: chr8-90955595;