Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1PP3_Strong
The NM_000179.3(MSH6):āc.3649A>Gā(p.Arg1217Gly) variant causes a missense, splice region change. The variant allele was found at a frequency of 0.0000316 in 1,613,880 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (ā ā ). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R1217K) has been classified as Uncertain significance.
MSH6 (HGNC:7329): (mutS homolog 6) This gene encodes a member of the DNA mismatch repair MutS family. In E. coli, the MutS protein helps in the recognition of mismatched nucleotides prior to their repair. A highly conserved region of approximately 150 aa, called the Walker-A adenine nucleotide binding motif, exists in MutS homologs. The encoded protein heterodimerizes with MSH2 to form a mismatch recognition complex that functions as a bidirectional molecular switch that exchanges ADP and ATP as DNA mismatches are bound and dissociated. Mutations in this gene may be associated with hereditary nonpolyposis colon cancer, colorectal cancer, and endometrial cancer. Transcripts variants encoding different isoforms have been described. [provided by RefSeq, Jul 2013]
FBXO11 (HGNC:13590): (F-box protein 11) This gene encodes a member of the F-box protein family which is characterized by an approximately 40 amino acid motif, the F-box. The F-box proteins constitute one of the four subunits of ubiquitin protein ligase complex called SCFs (SKP1-cullin-F-box), which function in phosphorylation-dependent ubiquitination. The F-box proteins are divided into 3 classes: Fbws containing WD-40 domains, Fbls containing leucine-rich repeats, and Fbxs containing either different protein-protein interaction modules or no recognizable motifs. The protein encoded by this gene belongs to the Fbxs class. It can function as an arginine methyltransferase that symmetrically dimethylates arginine residues, and it acts as an adaptor protein to mediate the neddylation of p53, which leads to the suppression of p53 function. This gene is known to be down-regulated in melanocytes from patients with vitiligo, a skin disorder that results in depigmentation. Polymorphisms in this gene are associated with chronic otitis media with effusion and recurrent otitis media (COME/ROM), a hearing loss disorder, and the knockout of the homologous mouse gene results in the deaf mouse mutant Jeff (Jf), a single gene model of otitis media. Alternatively spliced transcript variants encoding distinct isoforms have been identified for this gene. [provided by RefSeq, Jun 2010]
Verdict is Likely_pathogenic. Variant got 6 ACMG points.
PM1
In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 16 uncertain in NM_000179.3
PP3
MetaRNN computational evidence supports a deleterious effect, 0.987
Uncertain significance, criteria provided, single submitter
clinical testing
Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine
Aug 12, 2016
Variant identified in a genome or exome case(s) and assessed due to predicted null impact of the variant or pathogenic assertions in the literature or databases. Disclaimer: This variant has not undergone full assessment. The following are preliminary notes: Reported in 1 family with prostate cancer and demonstrated "partial" segregation (not sure what that means, but other uses of this term in the paper included examples of nonsegregation, ie affected individuals who did not carry the variant); ClinVar: 1 VUS -
Uncertain significance, criteria provided, single submitter
clinical testing
Women's Health and Genetics/Laboratory Corporation of America, LabCorp
Nov 27, 2023
Variant summary: MSH6 c.3649A>G (p.Arg1217Gly) results in a non-conservative amino acid change located in the DNA mismatch repair protein Mut S, C-terminal domain (IPR000432) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. Consensus agreement among computation tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. The variant was absent in 251192 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.3649A>G has been reported in the literature in individuals affected with prostrate cancer (Leongamornlert_2014), colon cancer of cecum with proficient MMR status (Pearlman_2017), and sebaceous neoplasms with loss of MLH1 and PMS2 on tumor IHC and no significant family history (Schon_2018). These report(s) do not provide unequivocal conclusions about association of the variant with MSH6-associated Lynch syndrome. 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: 24556621, 27978560, 29333623). Five submitters have cited clinical-significance assessments for this variant to ClinVar after 2014, and all submitters classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -
Uncertain significance, criteria provided, single submitter
clinical testing
Ambry Genetics
Feb 01, 2023
The p.R1217G variant (also known as c.3649A>G), located in coding exon 8 of the MSH6 gene, results from an A to G substitution at nucleotide position 3649. The arginine at codon 1217 is replaced by glycine, an amino acid with dissimilar properties. This has been identified in individuals with a personal and/or family history of prostate cancer (Leongamornlert D et al Br J Cancer. 2014 Mar 18;110(6):1663-72; Matejcic M et al. JCO Precis Oncol, 2020 Jan;4:32-43). This alteration has also been previously identified in an individual from a North American cohort of individuals with early onset colon cancer (Pearlman R et al. JAMA Oncol, 2017 Apr;3:464-471). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -
Uncertain significance, criteria provided, single submitter
clinical testing
Color Diagnostics, LLC DBA Color Health
Mar 20, 2023
This missense variant replaces arginine with glycine at codon 1217 of the MSH6 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in individuals affected with colorectal adenocarcinoma, sebaceous neoplasms, and prostate cancer (PMID: 24556621, 27978560, 29333623). This variant has been identified in 1/31404 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 Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
All of Us Research Program, National Institutes of Health
Oct 06, 2023
This missense variant replaces arginine with glycine at codon 1217 of the MSH6 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in individuals affected with colorectal adenocarcinoma, sebaceous neoplasms, and prostate cancer in the literature (PMID: 24556621, 27978560, 29333623). This variant has been identified in 1/31404 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. -
not provided Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
GeneDx
Jun 06, 2023
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 individuals with sebaceous neoplasm, cecal, or prostate cancer (Leongamornlert et al., 2014; Pearlman et al., 2017; Schon et al., 2018; Matejcic et al., 2020); This variant is associated with the following publications: (PMID: 24556621, 27978560, 29596542, 29333623, 12019211, 17531815, 21120944, 32832836) -
Uncertain significance, criteria provided, single submitter
clinical testing
Labcorp Genetics (formerly Invitae), Labcorp
Oct 05, 2023
This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 1217 of the MSH6 protein (p.Arg1217Gly). This variant is present in population databases (rs587780677, gnomAD 0.007%). This missense change has been observed in individual(s) with colorectal cancer, prostate cancer, and sebaceous neoplasm (PMID: 24556621, 27978560, 29333623). ClinVar contains an entry for this variant (Variation ID: 135842). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. 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
Uncertain significance, criteria provided, single submitter