rs61754967
Variant summary
Our verdict is Benign. The variant received -13 ACMG points: 0P and 13B. BP4_StrongBP6BS1BS2
The NM_002485.5(NBN):c.758C>T(p.Thr253Ile) variant causes a missense change. The variant allele was found at a frequency of 0.000214 in 1,613,778 control chromosomes in the GnomAD database, including 2 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T253A) has been classified as Uncertain significance.
Frequency
Consequence
NM_002485.5 missense
Scores
Clinical Significance
Conservation
Publications
- Nijmegen breakage syndromeInheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Labcorp Genetics (formerly Invitae), ClinGen, Myriad Women’s Health
- rhabdomyosarcomaInheritance: AR Classification: MODERATE Submitted by: Genomics England PanelApp
- idiopathic aplastic anemiaInheritance: AD Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)
- prostate cancerInheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
- hereditary breast carcinomaInheritance: AD Classification: NO_KNOWN Submitted by: ClinGen
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ACMG classification
Our verdict: Benign. The variant received -13 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000920 AC: 14AN: 152110Hom.: 0 Cov.: 32 show subpopulations
GnomAD2 exomes AF: 0.000394 AC: 99AN: 251160 AF XY: 0.000567 show subpopulations
GnomAD4 exome AF: 0.000227 AC: 332AN: 1461550Hom.: 2 Cov.: 31 AF XY: 0.000347 AC XY: 252AN XY: 727088 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.0000920 AC: 14AN: 152228Hom.: 0 Cov.: 32 AF XY: 0.000134 AC XY: 10AN XY: 74428 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
not provided Uncertain:1Benign:3
The NBN p.Thr253Ile variant was identified in the literature from healthy individuals in 3 of 1362 control chromosomes (frequency: 0.002) (Bodian 2014). The variant was also identified in the following databases: dbSNP (ID: rs61754967) as "With Uncertain significance allele", ClinVar (2x uncertain significance, 2x likely benign), Clinvitae (2x uncertain significance, 1x likely benign), and the Zhejiang Colon Cancer Database. The variant was not identified in the Cosmic or LOVD 3.0 databases. The variant was identified in control databases in 100 of 276924 chromosomes (1 homozygous) at a frequency of 0.0004 (Genome Aggregation Database Feb 27, 2017). Breakdown of the observations by population include Other in 1 of 6454 chromosomes (freq: 0.0002) and South Asian in 99 of 30782 chromosomes (freq: 0.003). The variant was not observed in the African, Latino, European, Ashkenazi Jewish, East Asian, or Finnish populations. The p.Thr253 residue is not conserved in mammals and computational analyses (PolyPhen-2, SIFT, AlignGVGD, BLOSUM, MutationTaster) provide inconsistent predictions regarding the impact to the protein; this information is not very predictive of pathogenicity. The variant occurs outside of the splicing consensus sequence and in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer, HumanSpliceFinder) 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. -
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In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 24728327, 31278556) -
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Hereditary cancer-predisposing syndrome Uncertain:1Benign:2
This alteration is classified as 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. -
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Microcephaly, normal intelligence and immunodeficiency Benign:3
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. -
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not specified Benign:1Other:1
Variant summary: NBN c.758C>T (p.Thr253Ile) results in a non-conservative amino acid change located in the Nibrin, second BRCT domain of the encoded protein sequence. Four of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.00041 in 251260 control chromosomes, predominantly at a frequency of 0.0032 within the South Asian subpopulation in the gnomAD database, including 1 homozygote. The observed variant frequency within South Asian control individuals in the gnomAD database is approximately 1.3- fold the estimated maximal expected allele frequency for a pathogenic variant in NBN causing Nijmegen Breakage Syndrome phenotype (0.0025), suggesting that the variant is a benign polymorphism found primarily in populations of South Asian origin. c.758C>T has been reported in the literature in healthy individuals (e.g. Bodian_2014) and at least one cancer cell line (e.g. Sun_2018). These reports do 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. Six other clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation, citing the variant as benign/ likely benign (n=4) and uncertain significance (n=2). Based on the evidence outlined above, the variant was classified as likely benign. -
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NBN-related disorder Benign:1
This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at