2-47800329-CTG-C

Position:

• chr2-47800329-CTG-C

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000179.3(MSH6):​c.2348_2349del​(p.Cys783Ter) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,870 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★★). Synonymous variant affecting the same amino acid position (i.e. C783C) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: MSH6 NM_000179.3 frameshift
• Clinical Significance: Pathogenic reviewed by expert panel P:8
• Conservation: PhyloP100: 9.93

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 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 2-47800329-CTG-C is Pathogenic according to our data. Variant chr2-47800329-CTG-C is described in ClinVar as [Pathogenic]. Clinvar id is 89274.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr2-47800329-CTG-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MSH6	NM_000179.3	c.2348_2349del	p.Cys783Ter	frameshift_variant	4/10	ENST00000234420.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MSH6	ENST00000234420.11	c.2348_2349del	p.Cys783Ter	frameshift_variant	4/10	1	NM_000179.3	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461870 Hom.: 0 AF XY: 0.00000275 AC XY: 2 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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:8

Revision: reviewed by expert panel

Submissions by phenotype

Endometrial carcinoma Pathogenic:3

Pathogenic, no assertion criteria provided	clinical testing	CZECANCA consortium	Feb 21, 2023	- -
Pathogenic, no assertion criteria provided	clinical testing	Department of Pathology and Laboratory Medicine, Sinai Health System	-	The MSH6 p.Cys783X variant was identified in individuals with HNPCC although no frequency data was provided (Steinke 2008, Talseth-Palmer 2010). The variant was also identified in dbSNP (ID: rs267608065) “With pathogenic allele”, the Clinvitae database as pathogenic, InSiGHT Colon Cancer Gene Variant Database as pathogenic, the ClinVar database (classified as a pathogenic variant and reviewed by an expert panel). The p.Cys783X variant leads to a premature stop codon at position 783, which is predicted to lead to a truncated or absent protein and loss of function. Loss of function variants of the MSH6 gene are an established mechanism of disease in Lynch syndrome and this is the type of variant expected to cause the disorder. In summary, based on the above information, this variant meets our laboratory’s criteria to be classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Jul 31, 2021	- -

Lynch syndrome 5 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Myriad Genetics, Inc.

Aug 17, 2023

This variant is considered pathogenic. This variant creates a termination codon and is predicted to result in premature protein truncation. -

Lynch syndrome Pathogenic:1

Pathogenic, reviewed by expert panel

research

International Society for Gastrointestinal Hereditary Tumours (InSiGHT)

Sep 05, 2013

Coding sequence variation resulting in a stop codon -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Jan 23, 2017

This deletion of two nucleotides is denoted MSH6 c.2348_2349delGT at the cDNA level and p.Cys783Ter (C783X) at the protein level. The normal sequence, with the bases that are deleted in brackets, is CTCT[delGT]AACC. The deletion creates a nonsense variant, which changes a Cysteine to a premature stop codon. This variant is predicted to cause loss of normal protein function through either protein truncation or nonsense-mediated mRNA decay. MSH6 c.2348_2349delGT has been reported in two individuals with colorectal cancer whose tumors showed loss of MSH6 protein on immunohistochemistry (Steinke 2008, Talseth-Palmer 2010). This variant is considered pathogenic. -

Hereditary nonpolyposis colorectal neoplasms Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Feb 25, 2023

This sequence change creates a premature translational stop signal (p.Cys783*) in the MSH6 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in MSH6 are known to be pathogenic (PMID: 18269114, 24362816). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with colon cancer (PMID: 18301448, 20487569). ClinVar contains an entry for this variant (Variation ID: 89274). For these reasons, this variant has been classified as Pathogenic. -

Hereditary cancer-predisposing syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 05, 2021

The c.2348_2349delGT pathogenic mutation, located in coding exon 4 of the MSH6 gene, results from a deletion of two nucleotides at nucleotide positions 2348 to 2349, causing a translational frameshift with a predicted alternate stop codon (p.C783*). The alteration was initially reported in an individual meeting revised Bethesda criteria who was diagnosed with colon cancer at the age of 47 and had secondary neoplasia diagnosed at 47 as well as 48. Tumor analysis showed MSI-H and loss of MSH6 by IHC (Steinke V et al. Eur. J. Hum. Genet. 2008 May; 16(5):587-92). This alteration was also identified in an individual diagnosed with colon cancer at the age of 38, but had no family history of cancer. Although he did not fulfill Amsterdam II criteria, IHC tumor analysis showed isolated loss of MSH6 (Talseth-Palmer B.A. et al. Hered Cancer Clin Pract 2010;8(1):5). In addition to the clinical data presented in the literature, this alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. As such, this alteration is interpreted as a disease-causing mutation. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs267608065; hg19: chr2-48027468;