rs561198849

chr2-47800274-C-Achr2-47800274-C-Gchr2-47800274-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM1 PP3

The NM_000179.3(MSH6):c.2291C>A(p.Thr764Asn) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000105 in 1,614,040 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 13/20 in silico tools predict 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. T764I) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000010 (0 hom.)
• Consequence: MSH6 NM_000179.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:10 B:1
• Conservation: PhyloP100: 3.33

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 Uncertain_significance. Variant got 3 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 16 uncertain in NM_000179.3
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.762

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MSH6	NM_000179.3	c.2291C>A	p.Thr764Asn	missense_variant	4/10	ENST00000234420.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MSH6	ENST00000234420.11	c.2291C>A	p.Thr764Asn	missense_variant	4/10	1	NM_000179.3	P4

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152164 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000159 AC: 4 AN: 251148 Hom.: 0 AF XY: 0.0000295 AC XY: 4 AN XY: 135722

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: 0.0000980

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000881

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000103 AC: 15 AN: 1461876 Hom.: 0 Cov.: 34 AF XY: 0.0000138 AC XY: 10 AN XY: 727238

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: 0.0000696

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000629

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152164 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74324

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.0000655

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000113

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:10 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Dec 08, 2022	This missense variant replaces threonine with asparagine at codon 764 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 reported in an individual with colorectal cancer, however, this individual also carried a pathogenic variant in the MLH1 gene that could explain the observed phenotype (PMID: 15713769). This variant has also been reported in an individual affected with hereditary breast cancer (PMID: 32547938). This variant has been identified in 5/282546 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	Nov 01, 2022	The p.T764N variant (also known as c.2291C>A), located in coding exon 4 of the MSH6 gene, results from a C to A substitution at nucleotide position 2291. The threonine at codon 764 is replaced by asparagine, an amino acid with similar properties. This variant has been identified in a proband(s) who met Amsterdam I/II criteria for Lynch syndrome and tumor demonstrated high microsatellite instability; however, this variant was seen in conjunction with a pathogenic MLH1 variant (Casey G et al. JAMA 2005 Feb;293(7):799-809). This variant was also reported in one of 711 Russian women with breast cancer but was absent from 492 healthy controls. The patient with this variant also reportedly carried a BRCA2 pathogenic mutation (Nikitin AG et al. Front Oncol, 2020 May;10:666). This amino acid position is not well conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -
Uncertain significance, criteria provided, single submitter	curation	Sema4, Sema4	Feb 05, 2022	- -

Lynch syndrome 5 Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Mar 28, 2023	This variant is classified as a variant of uncertain significance as there is insufficient evidence to determine its impact on protein function and/or cancer risk. -
Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Dec 29, 2017	- -

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Aug 20, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Dec 01, 2020	Not observed at a significant frequency in large population cohorts (Lek 2016); In silico analysis supports that this missense variant does not alter protein structure/function; Observed in individuals with a personal or family history including breast cancer (Nikitin 2020); Observed in an individual in published literature (Casey 2005) who had a different genetic etiology for colorectal cancer; This variant is associated with the following publications: (PMID: 15713769, 23621914, 32547938) -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Oct 10, 2022

Variant summary: MSH6 c.2291C>A (p.Thr764Asn) results in a non-conservative amino acid change DNA mismatch repair protein MutS core (IPR007696) of the encoded protein sequence. Three of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 1.6e-05 in 251148 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.2291C>A has been reported in the literature in individuals affected with Colorectal cancer and Breast cancer without stong evidence for causality (Casey_2005, Nikitin_2020). These data do not allow any conclusion about variant significance. Co-occurrence with another pathogenic variant have been reported (MLH1 c.350C>G, p.Thr117Arg), providing supporting evidence for a benign role. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Seven clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Lynch syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

All of Us Research Program, National Institutes of Health

Aug 15, 2023

This missense variant replaces threonine with asparagine at codon 764 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 reported in an individual with colorectal cancer, however, this individual also carried a pathogenic variant in the MLH1 gene that could explain the observed phenotype (PMID: 15713769). This variant has also been reported in an individual affected with hereditary breast cancer (PMID: 32547938). This variant has been identified in 5/282546 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. -

Endometrial carcinoma Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Baylor Genetics

Oct 12, 2023

- -

Hereditary nonpolyposis colorectal neoplasms Benign:1

Benign, criteria provided, single submitter

clinical testing

Invitae

Jan 25, 2024

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.10
BayesDel_addAF	Benign	-0.080	T
BayesDel_noAF	Benign	-0.15
Cadd	Benign	17
Dann	Benign	0.93
Eigen	Benign	-0.16
Eigen_PC	Benign	0.048
FATHMM_MKL	Pathogenic	0.97	D
M_CAP	Uncertain	0.13	D
MetaRNN	Pathogenic	0.76	D;D;D;D;D
MetaSVM	Uncertain	-0.19	T
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Benign	0.36	T
Sift4G	Benign	0.47	T;T;T;T;T
Polyphen		0.014	.;.;B;.;.
Vest4		0.67
MutPred		0.78		.;.;Gain of catalytic residue at T764 (P = 0.0878);.;.;
MVP		0.94
ClinPred		0.11	T
GERP RS		5.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.34
gMVP		0.40

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: rs561198849; hg19: chr2-48027413; COSMIC: COSV99029740; COSMIC: COSV99029740;