chr2-47803663-G-A

Position:

• chr2-47803663-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PM5 PP3 PP5

The NM_000179.3(MSH6):​c.3416G>A​(p.Gly1139Asp) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,888 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 8/13 in silico tools predict a damaging 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. G1139C) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: MSH6 NM_000179.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:3
• Conservation: PhyloP100: 9.97

Genes affected

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 3 benign, 17 uncertain in NM_000179.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr2-47803662-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1731205.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.801
• PP5: Variant 2-47803663-G-A is Pathogenic according to our data. Variant chr2-47803663-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 581014.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=3, Uncertain_significance=3}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MSH6	NM_000179.3	c.3416G>A	p.Gly1139Asp	missense_variant	5/10	ENST00000234420.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MSH6	ENST00000234420.11	c.3416G>A	p.Gly1139Asp	missense_variant	5/10	1	NM_000179.3	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251346 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135852

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461888 Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1 AN XY: 727244

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:3

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Lynch syndrome 5 Pathogenic:1 Uncertain:1

Uncertain significance, criteria provided, single submitter	clinical testing	Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center	Mar 26, 2024	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Aug 23, 2023	This variant is considered likely pathogenic. Functional studies indicate this variant impacts protein function [PMID: 31965077]. This variant is expected to disrupt protein structure [Myriad internal data]. -

Hereditary cancer-predisposing syndrome Pathogenic:1 Uncertain:1

Likely pathogenic, criteria provided, single submitter	clinical testing	Ambry Genetics	May 27, 2024	The p.G1139D variant (also known as c.3416G>A), located in coding exon 5 of the MSH6 gene, results from a G to A substitution at nucleotide position 3416. The glycine at codon 1139 is replaced by aspartic acid, an amino acid with similar properties. This variant has been identified in a proband whose Lynch syndrome-associated tumor demonstrated loss of MSH6 expression by immunohistochemistry (Ambry internal data). Another variant at the same codon, p.G1139S (c.3415G>A), demonstrated deficient mismatch repair activity in functional studies and was detected in individuals with MSI-H colorectal tumors that showed loss of MSH2 and/or MSH6 expression by immunohistochemistry (Drost M et al. Hum Mutat, 2012 Mar;33:488-94; Wielders EA et al. PLoS One, 2013 Sep;8:e74766; Houlleberghs H et al. PLoS Genet, 2017 May;13:e1006765; Drost M et al. Genet Med, 2020 05;22:847-856; Woods MO et al. Clin Cancer Res, 2005 Oct;11:6853-61; Steinke V et al. Eur J Hum Genet, 2008 May;16:587-92). Based on internal structural analysis, G1139D disrupts a key position in the MSH6 phosphate-binding motif (Walker JE et al. EMBO J, 1982;1:945-51; Antony E et al. DNA Repair (Amst), 2006 Feb;5:153-62; Warren JJ et al. Mol Cell, 2007 May;26:579-92; Ambry internal data). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the majority of available evidence to date, this variant is likely to be pathogenic. -
Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Nov 03, 2020	This missense variant replaces a conserved glycine with aspartic acid at codon 1139 in the ATPase domain (the Walker A motif) 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). Functional studies have shown that this variant protein and its equivalent in the mouse and budding yeast MSH6 homologs are defective in DNA mismatch repair and associated activities (PMID: 9819445, 31965077). To our knowledge, this variant has not been reported in individuals affected with hereditary cancer in the literature. However, a different missense variant p.Gly1139Ser has been observed in at least two individuals affected with Lynch syndrome (PMID: 16203774, 18301448) and found to be defective in DNA mismatch repair and related functional assays (PMID: 22102614, 24040339, 28531214, 31965077). This variant has been identified in 1/251346 chromosomes in the general population by the Genome Aggregation Database (gnomAD). Although there is a suspicion that this variant may be associated with disease, additional studies are necessary to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 28, 2023

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. RNA analysis performed to evaluate the impact of this missense change on mRNA splicing indicates it does not significantly alter splicing (PMID: 32123317). Experimental studies have shown that this missense change affects MSH6 function (PMID: 31965077). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt MSH6 protein function. ClinVar contains an entry for this variant (Variation ID: 581014). This variant has not been reported in the literature in individuals affected with MSH6-related conditions. This variant is present in population databases (no rsID available, gnomAD 0.003%). This sequence change replaces glycine, which is neutral and non-polar, with aspartic acid, which is acidic and polar, at codon 1139 of the MSH6 protein (p.Gly1139Asp). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.44	D
BayesDel_noAF	Pathogenic	0.61
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Benign	0.17	T
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Benign	0.30	T
M_CAP	Pathogenic	0.51	D
MetaRNN	Pathogenic	0.80	D
MetaSVM	Pathogenic	0.95	D
MutationTaster	Benign	1.0	D;D;D;D
Sift4G	Uncertain	0.0070	D
Vest4		0.64
MVP		0.94
ClinPred		1.0	D
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.8

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1316409501; hg19: chr2-48030802;