2-47798981-C-T
Variant summary
Our verdict is Likely benign. Variant got -3 ACMG points: 0P and 3B. BP4_ModerateBP6
The NM_000179.3(MSH6):c.998C>T(p.Thr333Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000124 in 1,614,098 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 Conflicting classifications of pathogenicity (no stars).
Frequency
Consequence
NM_000179.3 missense
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Likely_benign. Variant got -3 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.00000657 AC: 1AN: 152214Hom.: 0 Cov.: 32
GnomAD4 exome AF: 0.0000130 AC: 19AN: 1461884Hom.: 0 Cov.: 34 AF XY: 0.0000138 AC XY: 10AN XY: 727240
GnomAD4 genome AF: 0.00000657 AC: 1AN: 152214Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0AN XY: 74358
ClinVar
Submissions by phenotype
Hereditary cancer-predisposing syndrome Uncertain:3Benign:1
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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. -
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This missense variant replaces threonine with isoleucine at codon 333 of the MSH6 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been identified in individuals affected with colorectal or pancreatic cancer (PMID: 26300997, 35886069). This variant has been identified in 1/31406 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -
Lynch syndrome 5 Uncertain:3
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The MSH6 c.998C>T (p.Thr333Ile) missense change has a maximum subpopulation frequency of 0.0065% in gnomAD v2.1.1 (PM2_supporting; https://gnomad.broadinstitute.org/). In silico tools are inconclusive about the effect of this variant on protein function, and to our knowledge functional assays have not been performed. This variant has been reported in an individual with Lynch syndrome who harbored a pathogenic variant in MLH1 (BP5; PMID: 26300997). In summary, this variant meets criteria to be classified as of uncertain significance based on the ACMG/AMP criteria: PM2_supporting, BP5. -
ACMG classification criteria: PM2 moderated, BP4 supporting -
not provided Uncertain:2
Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Observed in an individual with Lynch syndrome who also harbored a pathogenic MLH1 variant and in individuals with pancreatic or breast cancer (PMID: 26300997, 25186627, 32658311, 35886069); This variant is associated with the following publications: (PMID: 28717660, 18523027, 27311873, 31422574, 35886069, 21437237, 25186627, 26300997, 32658311, 34284872) -
The frequency of this variant in the general population, 0.000032 (1/31406 chromosomes, http://gnomad.broadinstitute.org), is uninformative in assessment of its pathogenicity. In the published literature, the variant has been reported in an individual with Lynch syndrome who also carried a pathogenic variant in the MLH1 gene, suggesting the MSH6 c.998C>T (p.Thr333Ile) variant may not the primary cause of disease. In addition, this variant has been observed in an individual with pancreatic cancer (PMID: 35886069 (2022)), and in several breast cancer cases and a control individual in a large-scale breast cancer association study (see LOVD (http://databases.lovd.nl/shared/genes/MSH6) and PMID: 33471991 (2021)). 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. -
Endometrial carcinoma;C1833477:Lynch syndrome 5;C5436807:Mismatch repair cancer syndrome 3 Uncertain:1
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Hereditary nonpolyposis colorectal neoplasms Uncertain:1
This sequence change replaces threonine, which is neutral and polar, with isoleucine, which is neutral and non-polar, at codon 333 of the MSH6 protein (p.Thr333Ile). This variant is present in population databases (rs587781983, gnomAD 0.007%). This missense change has been observed in individual(s) with Lynch syndrome, however, in that individual a pathogenic allele was also identified in the MLH1 gene, which suggests that this c.998C>T variant was not the primary cause of disease (PMID: 26300997). ClinVar contains an entry for this variant (Variation ID: 141751). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt MSH6 protein function with a negative predictive value of 95%. 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. -
Endometrial carcinoma Uncertain:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at