2-47806650-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM5

The NM_000179.3(MSH6):c.4000C>T(p.Arg1334Trp) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000349 in 1,606,498 control chromosomes in the GnomAD database, with no homozygous occurrence. 3/3 splice prediction tools predict no significant impact on normal splicing. 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. R1334Q) has been classified as Pathogenic.

• Frequency:
  • Genomes: 𝑓 0.000053 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000033 (0 hom.)
• Consequence: MSH6 NM_000179.3 missense, splice_region
• Scores: Splicing: ADA: 0.1288
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:9 B:1
• Conservation: PhyloP100: 3.37

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 2 ACMG points.

• PM5: Other missense variant is known to change same aminoacid residue: Variant chr2-47806651-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 89506.Status of the report is reviewed_by_expert_panel, 3 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MSH6	NM_000179.3	c.4000C>T	p.Arg1334Trp	missense_variant, splice_region_variant	9/10	ENST00000234420.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MSH6	ENST00000234420.11	c.4000C>T	p.Arg1334Trp	missense_variant, splice_region_variant	9/10	1	NM_000179.3	P4

Frequencies

GnomAD3 genomes AF: 0.0000528 AC: 8 AN: 151444 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000973

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000658

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: 0.0000441

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000368 AC: 9 AN: 244568 Hom.: 0 AF XY: 0.0000302 AC XY: 4 AN XY: 132618

Gnomad AFR exome AF: 0.000127

Gnomad AMR exome AF: 0.0000874

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000329

Gnomad FIN exome AF: 0.0000520

Gnomad NFE exome AF: 0.0000181

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000330 AC: 48 AN: 1455054 Hom.: 0 Cov.: 35 AF XY: 0.0000207 AC XY: 15 AN XY: 724122

Gnomad4 AFR exome AF: 0.0000300

Gnomad4 AMR exome AF: 0.0000896

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.0000400

Gnomad4 NFE exome AF: 0.0000334

Gnomad4 OTH exome AF: 0.0000498

GnomAD4 genome AF: 0.0000528 AC: 8 AN: 151444 Hom.: 0 Cov.: 32 AF XY: 0.0000812 AC XY: 6 AN XY: 73892

Gnomad4 AFR AF: 0.0000973

Gnomad4 AMR AF: 0.0000658

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000441

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000568 Hom.: 0

Bravo AF: 0.0000642

ExAC AF: 0.0000412 AC: 5

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:9 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Lynch syndrome 5 Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Dec 28, 2015	- -
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. -

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Aug 03, 2023	In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Observed in an individual with a personal and family history of colon cancer as well as individuals with a personal history of breast cancer, one of whom also had pancreatic cancer (Chubb et al., 2015; Dudley et al., 2018; Hu et al., 2022; Dorling et al., 2021); This variant is associated with the following publications: (PMID: 25559809, 25275298, 29360161, 31391288, 23415222, 33471991, 35449176, 21120944, 12019211, 17531815, 25370038) -
Uncertain significance, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Oct 15, 2019	- -

Hereditary cancer-predisposing syndrome Uncertain:1 Benign:1

Likely benign, criteria provided, single submitter	clinical testing	Ambry Genetics	Oct 12, 2023	This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -
Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Nov 01, 2022	This missense variant replaces arginine with tryptophan at codon 1334 of the MSH6 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in an individual affected by early-onset, familial colorectal cancer (PMID: 25559809). This variant has been identified in 11/275890 chromosomes in the general population by the Genome Aggregation Database (gnomAD). A different variant affecting the same codon, c.4001G>A (p.Arg1334Gln), is considered to be disease-causing (ClinVar variation ID: 89506), suggesting that this position is important for the protein function. 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 specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Aug 06, 2021

Variant summary: MSH6 c.4000C>T (p.Arg1334Trp) results in a non-conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. 4/4 computational tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 3.7e-05 in 244568 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.4000C>T has been reported in the literature as somatic occurrence in individuals affected with chronic lymphocytic leukemia, HNSCC, polyposis and endometrial cancer (Landau_2013, Martin_2014, Elsayed_2015) and as germline occurrence in individuals affected with cancer including colorectal, pancreatic and breast cancer (Chubb_2015, Dudley_2018, Li_2020, Dorling_2021), but it was also reported in controls (Dorling_2021). These reports do not provide unequivocal conclusions about association of the variant with Lynch Syndrome. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Six ClinVar submitters (evaluation after 2014) cite 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

Nov 30, 2023

This missense variant replaces arginine with tryptophan at codon 1334 of the MSH6 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in an individual affected by early-onset, familial colorectal cancer (PMID: 25559809). This variant has been identified in 11/275890 chromosomes in the general population by the Genome Aggregation Database (gnomAD). A different variant affecting the same codon, c.4001G>A (p.Arg1334Gln), is considered to be disease-causing (ClinVar variation ID: 89506), suggesting that this position is important for the protein function. 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. -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jan 24, 2024

This sequence change replaces arginine, which is basic and polar, with tryptophan, which is neutral and slightly polar, at codon 1334 of the MSH6 protein (p.Arg1334Trp). This variant is present in population databases (rs773763465, gnomAD 0.01%). This missense change has been observed in individual(s) with colorectal cancer, breast cancer, and/or pancreatic cancer (PMID: 25559809, 29360161, 35449176). ClinVar contains an entry for this variant (Variation ID: 184389). 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. Studies have shown that this missense change is associated with inconclusive levels of altered splicing (Invitae). 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

clinical testing

Baylor Genetics

Oct 12, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.35
BayesDel_addAF	Pathogenic	0.18	D
BayesDel_noAF	Pathogenic	0.26
Cadd	Uncertain	25
Dann	Uncertain	1.0
Eigen	Uncertain	0.46
Eigen_PC	Uncertain	0.48
FATHMM_MKL	Uncertain	0.87	D
M_CAP	Uncertain	0.26	D
MetaRNN	Uncertain	0.66	D;D;D;D;D
MetaSVM	Uncertain	0.36	D
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.49	T
Sift4G	Uncertain	0.0090	D;D;D;D;D
Polyphen		1.0	.;.;.;D;.
Vest4		0.71
MutPred		0.58		.;.;.;Gain of catalytic residue at L1332 (P = 0.0058);.;
MVP		0.95
ClinPred		0.67	D
GERP RS		4.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.69
gMVP		0.70

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.13
dbscSNV1_RF	Benign	0.32
SpliceAI score (max)		0.070		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: rs773763465; hg19: chr2-48033789; COSMIC: COSV52273496; COSMIC: COSV52273496;