2-47804932-C-A

Position:

• chr2-47804932-C-A

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PP3_Strong PP5

The ENST00000234420.11(MSH6):​c.3461C>A​(p.Ala1154Asp) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic 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. A1154G) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MSH6 ENST00000234420.11 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 7.57

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 9 ACMG points.

• PM1: In a hotspot region, there are 8 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 4 benign, 17 uncertain in ENST00000234420.11
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.984
• PP5: Variant 2-47804932-C-A is Pathogenic according to our data. Variant chr2-47804932-C-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 186296.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MSH6	NM_000179.3	c.3461C>A	p.Ala1154Asp	missense_variant	6/10	ENST00000234420.11	NP_000170.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MSH6	ENST00000234420.11	c.3461C>A	p.Ala1154Asp	missense_variant	6/10	1	NM_000179.3	ENSP00000234420	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000282 Hom.: 0

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Hereditary cancer-predisposing syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Jul 20, 2023

The p.A1154D variant (also known as c.3461C>A), located in coding exon 6 of the MSH6 gene, results from a C to A substitution at nucleotide position 3461. The alanine at codon 1154 is replaced by aspartic acid, an amino acid with dissimilar properties. Based on an internal structural analysis, A1154D is moderately disruptive to the structure of the MSH6 ATPase domain, introducing a large, charged side-chain into the hydrophobic core of the domain and is more disruptive than a pathogenic variant nearby through a comparable mechanism (Ambry internal data). This alteration has been observed in at least one individual with a personal and/or family history that is consistent with MSH6-related disease (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. This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 15, 2023

This sequence change replaces alanine, which is neutral and non-polar, with aspartic acid, which is acidic and polar, at codon 1154 of the MSH6 protein (p.Ala1154Asp). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with MSH6-related conditions. ClinVar contains an entry for this variant (Variation ID: 186296). 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. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.46
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.63	.;.;D;D;.
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.91
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.97	.;D;D;D;D
M_CAP	Pathogenic	0.57	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.8	.;.;.;H;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.78	T
PROVEAN	Pathogenic	-5.3	.;D;.;D;D
REVEL	Pathogenic	0.96
Sift	Uncertain	0.0010	.;D;.;D;D
Sift4G	Uncertain	0.0020	D;D;D;D;D
Polyphen		1.0	.;.;.;D;.
Vest4		0.98
MutPred		0.90		.;.;.;Loss of MoRF binding (P = 0.0994);.;
MVP		0.97
ClinPred		1.0	D
GERP RS		5.2
RBP_binding_hub_radar		0.97
RBP_regulation_power_radar		2.8
Varity_R		1.0
gMVP		0.98

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: rs786202842; hg19: chr2-48032071;