NM_000179.3:c.2300C>T

Variant names:

• chr2-47800283-C-T
• rs587781462
• NM_000179.3:c.2300C>T

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PP3_Strong PP5_Very_Strong

The NM_000179.3(MSH6):​c.2300C>T​(p.Thr767Ile) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000479 in 1,461,870 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: MSH6 NM_000179.3 missense
• Clinical Significance: Pathogenic reviewed by expert panel P:10 U:2
• Conservation: PhyloP100: 7.85

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 Pathogenic. Variant got 12 ACMG points.

• PP3: MetaRNN computational evidence supports a deleterious effect, 0.99
• PP5: Variant 2-47800283-C-T is Pathogenic according to our data. Variant chr2-47800283-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 141058.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr2-47800283-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MSH6	NM_000179.3	c.2300C>T	p.Thr767Ile	missense_variant	Exon 4 of 10	ENST00000234420.11	NP_000170.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MSH6	ENST00000234420.11	c.2300C>T	p.Thr767Ile	missense_variant	Exon 4 of 10	1	NM_000179.3	ENSP00000234420.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000479 AC: 7 AN: 1461870 Hom.: 0 Cov.: 34 AF XY: 0.00000550 AC XY: 4 AN XY: 727234

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000629

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:10 Uncertain:2

Revision: reviewed by expert panel

Submissions by phenotype

Hereditary cancer-predisposing syndrome Pathogenic:3

Oct 24, 2023

Color Diagnostics, LLC DBA Color Health

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces threonine with isoleucine at codon 767 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). A functional study has shown that this variant results in a significant decrease in mismatch repair activity compared to wild type MSH6 protein (PMID: 31965077). This variant has been reported in individuals affected with endometrial, uterine, and colorectal cancers (PMID: 29755653, 31100584, 33467402; ClinVar SCV000184163.7), and it has been shown that this variant segregates with disease in one family (PMID: 31100584). This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Based on the available evidence, this variant is classified as Pathogenic. -

Aug 11, 2021

Sema4, Sema4

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: curation

- -

May 29, 2024

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.T767I pathogenic mutation (also known as c.2300C>T), located in coding exon 4 of the MSH6 gene, results from a C to T substitution at nucleotide position 2300. The threonine at codon 767 is replaced by isoleucine, an amino acid with similar properties. This alteration was identified in several individuals whose Lynch-related tumors demonstrated high microsatellite instability and/or demonstrated loss of MSH6 expression on immunohistochemistry (IHC) and family history meets Amsterdam criteria (Ambry internal data; Fokkema IF et al. Hum. Mutat., 2011 May;32:557-63; Stembalska A et al. Eur. J. Obstet. Gynecol. Reprod. Biol., 2019 Jul;238:54-57). This alteration is also present in five first degree female relatives diagnosed with endometrial cancer (Stembalska A et al. Eur. J. Obstet. Gynecol. Reprod. Biol., 2019 Jul;238:54-57). In one in vitro complementation assay, mismatch repair activity for this variant was similar to that of the pathogenic control (Drost M et al. Genet Med, 2020 05;22:847-856). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -

Lynch syndrome 5 Pathogenic:1 Uncertain:1

Jul 10, 2023

Myriad Genetics, Inc.

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered likely pathogenic. Functional studies indicate this variant impacts protein function. This variant is expected to disrupt protein structure [Myriad internal data]. -

Dec 23, 2015

Counsyl

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Carcinoma of colon Pathogenic:1

-

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

The MSH6 p.Thr767Ile variant was identified in the literature found in patient with clear cell carcinoma of the uterus and absence of MSH6 protein and presence of protein for MLH1, MSH2 and PMS2 on IHC (Gray 2018), found in patient in second recurrence heterogeneously enhancing infiltrating tumor (Erson-Omay 2017) and in an endometrial cancer patient with isolated loss of MSH6 in tumour (McGill University Health Centre personal communication). In addition, the variant was identified in our laboratory in one family with segregation in 3 individuals. The variant was also identified in dbSNP (ID: rs587781462) as "With Pathogenic, Uncertain significance allele", ClinVar (classified as pathogenic by InSight; as likely pathogenic by Ambry Genetics; as uncertain significance by Invitae, Counsyl and COGR). The variant was not identified in UMD-LSDB. The variant was not identified in the following control databases: the Exome Aggregation Consortium (August 8th 2016), or the Genome Aggregation Database (Feb 27, 2017). The p.Thr767 residue is conserved across mammals and other organisms, and computational analyses (PolyPhen-2, SIFT, AlignGVGD, BLOSUM, MutationTaster) suggest that the variant may impact the protein; however, this information is not predictive enough to assume pathogenicity. The variant occurs outside of the splicing consensus sequence and in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer) do not predict a difference in splicing. In summary, based on the above information the clinical significance of this variant cannot be determined with certainty at this time although we would lean towards a more pathogenic role for this variant. This variant is classified as likely pathogenic. -

Hereditary nonpolyposis colon cancer Pathogenic:1

Nov 14, 2022

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: MSH6 c.2300C>T (p.Thr767Ile) results in a non-conservative amino acid change located in the core domain (IPR007696) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 251156 control chromosomes (gnomAD). c.2300C>T has been reported in the literature in individuals affected with endometrial cancer (example: Adar_2018, Stembalska_2019, and Lawrence_2021). In one family, this variant has been reported to segregate with the disease (Stembalska_2019). These data indicate that the variant is very likely to be associated with disease. In functional in vitro studies, the variant was found to have reduced mismatch repair (MMR) activity (Drost_2020). Seven clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and classified the variant as VUS (n=2) and pathogenic/likely pathogenic (n=5). Based on the evidence outlined above, the variant was classified as pathogenic. -

Lynch syndrome 1 Pathogenic:1

Mar 09, 2018

International Society for Gastrointestinal Hereditary Tumours (InSiGHT)

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: curation

Class 5 - Pathogenic Classification using multifactorial probability: 0.993 -

Rhabdomyosarcoma Pathogenic:1

Sep 01, 2020

Human Genome Sequencing Center Clinical Lab, Baylor College of Medicine

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: provider interpretation

- -

not provided Pathogenic:1

Jan 29, 2024

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); Published functional studies demonstrate reduced in vitro mismatch repair activity compared to wild type (PMID: 31965077); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 28153049, 21520333, 33372952, 17531815, 21120944, 31100584, 29755653, 33281875, 33467402, 30128536, 31965077, 29750335) -

Hereditary nonpolyposis colorectal neoplasms Pathogenic:1

Oct 20, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces threonine, which is neutral and polar, with isoleucine, which is neutral and non-polar, at codon 767 of the MSH6 protein (p.Thr767Ile). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with clinical features of Lynch syndrome (PMID: 29755653, 31100584). It has also been observed to segregate with disease in related individuals. Invitae Evidence Modeling of clinical and family history, age, sex, and reported ancestry of multiple individuals with this MSH6 variant has been performed. This variant is expected to be pathogenic with a positive predictive value of at least 99%. This is a validated machine learning model that incorporates the clinical features of 1,370,736 individuals referred to our laboratory for MSH6 testing. ClinVar contains an entry for this variant (Variation ID: 141058). Invitae Evidence Modeling incorporating data from in vitro experimental studies (internal data) indicates that this missense variant is expected to disrupt MSH6 function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects MSH6 function (PMID: 31965077). For these reasons, this variant has been classified as Pathogenic. -

not specified Uncertain:1

Feb 23, 2017

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.59
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.94	.;.;D;D;.
Eigen	Pathogenic	0.94
Eigen_PC	Pathogenic	0.87
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.94	.;D;D;D;D
M_CAP	Pathogenic	0.68	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.7	.;.;H;.;.
PrimateAI	Uncertain	0.70	T
PROVEAN	Pathogenic	-5.7	.;D;D;.;D
REVEL	Pathogenic	0.97
Sift	Uncertain	0.0010	.;D;D;.;D
Sift4G	Pathogenic	0.0010	D;D;D;D;D
Polyphen		1.0	.;.;D;.;.
Vest4		0.98
MutPred		0.93		.;.;Loss of catalytic residue at T767 (P = 0.0359);.;.;
MVP		0.99
ClinPred		1.0	D
GERP RS		5.5
Varity_R		0.96
gMVP		0.90

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: rs587781462; hg19: chr2-48027422; COSMIC: COSV52283040; COSMIC: COSV52283040;