8-89946211-A-G
Variant summary
Our verdict is Likely benign. Variant got -5 ACMG points: 0P and 5B. BP4_StrongBP6
The NM_002485.5(NBN):āc.1999T>Cā(p.Ser667Pro) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000988 in 1,599,276 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
Frequency
Consequence
NM_002485.5 missense
Scores
Clinical Significance
Conservation
Genome browser will be placed here
ACMG classification
Verdict is Likely_benign. Variant got -5 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.000164 AC: 25AN: 152142Hom.: 0 Cov.: 32
GnomAD3 exomes AF: 0.0000557 AC: 14AN: 251130Hom.: 0 AF XY: 0.0000442 AC XY: 6AN XY: 135738
GnomAD4 exome AF: 0.0000919 AC: 133AN: 1447134Hom.: 0 Cov.: 32 AF XY: 0.0000874 AC XY: 63AN XY: 720786
GnomAD4 genome AF: 0.000164 AC: 25AN: 152142Hom.: 0 Cov.: 32 AF XY: 0.000202 AC XY: 15AN XY: 74320
ClinVar
Submissions by phenotype
Microcephaly, normal intelligence and immunodeficiency Uncertain:4
- -
- -
This sequence change replaces serine, which is neutral and polar, with proline, which is neutral and non-polar, at codon 667 of the NBN protein (p.Ser667Pro). This variant is present in population databases (rs587780091, gnomAD 0.01%). This missense change has been observed in individual(s) with breast cancer, colorectal cancer, ovarian cancer, and/or prostate cancer (PMID: 26315354, 29596542, 29659569, 30256826, 31206626, 35245693). ClinVar contains an entry for this variant (Variation ID: 127863). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Not Available"; PolyPhen-2: "Benign"; Align-GVGD: "Not Available". The proline amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -
- -
not provided Uncertain:2Benign:1
In silico analysis supports that this missense variant does not alter protein structure/function; Observed in individuals with ovarian, colon, and prostate cancer (PMID: 26315354, 29596542, 30256826, 29659569); This variant is associated with the following publications: (PMID: 30256826, 26315354, 29596542, 29659569, 32936981, 33471991, 36243179, 31206626, 36346689, 35245693) -
The NBN c.1999T>C (p.Ser667Pro) variant has been reported in the published literature in individuals with breast cancer (PMID: 31206626 (2019), 32936981 (2021), 33471991 (2021) see also LOVD (https://databases.lovd.nl/shared/)), ovarian cancer (PMID: 26315354 (2015)), colorectal cancer (PMID: 29596542 (2018)), prostate cancer (PMID: 29659569 (2018)), other unspecified cancer types (PMID: 36346689 (2023)), and an individual that met clinical criteria for Lynch Syndrome (PMID: 30256826 (2018)). Additionally, this variant has seen in reportedly healthy individuals (PMID: 26315354 (2015), 33471991 (2021) see also LOVD (https://databases.lovd.nl/shared/variants/), 36243179 (2022)). The frequency of this variant in the general population, 0.00017 (6/35408 chromosomes (Genome Aggregation Database, http://gnomad.broadinstitute.org)), is uninformative in the assessment of its pathogenicity. Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded predictions that this variant is benign. Based on the available information, we are unable to determine the clinical significance of this variant. -
- -
Hereditary cancer-predisposing syndrome Uncertain:1Benign:1
- -
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. -
not specified Uncertain:1
Variant summary: NBN c.1999T>C (p.Ser667Pro) results in a non-conservative amino acid change in 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 5.6e-05 in 251130 control chromosomes (gnomAD). This frequency is not significantly higher than expected for a pathogenic variant in NBN causing Nijmegen Breakage Syndrome (5.6e-05 vs 0.0025), allowing no conclusion about variant significance. c.1999T>C has been reported in the literature as a VUS in settings of multigene panel testing in individuals with cancers such as breast and ovarian (e.g., Ramus_2015, Weitzel_2019, Castillo-Guardiola_2022), colorectal (e.g., Hampel_2018, Martin-Morales_2018), and prostate (e.g., Paulo_2018) and in unaffected controls (e.g., Ramus_2015). These report(s) do not provide unequivocal conclusions about association of the variant with Nijmegen Breakage Syndrome and/or NBN-related cancers. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 29596542, 26315354, 31206626, 35245693, 30256826, 29659569, 36346689). Twelve submitters have reported clinical-significance assessments for this variant to ClinVar after 2014. Multiple submitters reported the variant with conflicting assessments (VUS, n = 10; likely benign, n = 2). Based on the evidence outlined above, the variant was classified as uncertain significance. -
Aplastic anemia;C0023449:Acute lymphoid leukemia;C0398791:Microcephaly, normal intelligence and immunodeficiency Uncertain:1
- -
Aplastic anemia Uncertain:1
This variant was determined to be of uncertain significance according to ACMG Guidelines, 2015 [PMID:25741868]. -
NBN-related disorder Uncertain:1
The NBN c.1999T>C variant is predicted to result in the amino acid substitution p.Ser667Pro. This variant has been reported in individuals with ovarian cancer and controls at approximately equal frequency (Ramus et al. 2015. PubMed ID: 26315354. Table S4). It has also been reported in individuals with colorectal cancer and interpreted as uncertain significance ( eTable 2, Hampel et al. 2018. PubMed ID: 29596542; Martin-Morales et al. 2018. PubMed ID: 30256826). This variant was also observed in the controls cohort at a carrier frequency of 0.001% but not in the cases cohort in a large study of hereditary cancer variants (Table S2, Okawa et al. 2023. PubMed ID: 36243179). This variant is reported in 0.017% of alleles in individuals of Latino descent in gnomAD and has conflicting interpretations of likely benign and uncertain significance in ClinVar (https://www.ncbi.nlm.nih.gov/clinvar/variation/127863/). At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at