rs63750595

Positions:

• chr2-47799659-G-A
• chr2-47799659-G-C
• chr2-47799659-G-T

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP3_Strong

The ENST00000234420.11(MSH6):​c.1676G>A​(p.Cys559Tyr) 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 Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C559R) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MSH6 ENST00000234420.11 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.94

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 10 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 17 uncertain in ENST00000234420.11
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr2-47799660-C-G is described in Lovd as [Likely_pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.955

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MSH6	NM_000179.3	c.1676G>A	p.Cys559Tyr	missense_variant	4/10	ENST00000234420.11	NP_000170.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MSH6	ENST00000234420.11	c.1676G>A	p.Cys559Tyr	missense_variant	4/10	1	NM_000179.3	ENSP00000234420	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Nov 11, 2016

This variant is denoted MSH6 c.1676G>A at the cDNA level, p.Cys559Tyr (C559Y) at the protein level, and results in the change of a Cysteine to a Tyrosine (TGC>TAC). This variant was observed in an individual with endometrial and a family history of ovarian cancer (Suchy 2006). MSH6 Cys559Tyr was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, suggesting it is not a common benign variant in these populations. Since Cysteine and Tyrosine differ in polarity, charge, size or other properties, this is considered a non-conservative amino acid substitution. MSH6 Cys559Tyr occurs at a position that is conserved in mammals and is located within the binding sites of MSH2 and domain II of the MutS domain (Kariola 2002, Terui 2013). In silico analyses predict that this variant is probably damaging to protein structure and function. Based on currently available evidence, it is unclear whether MSH6 Cys559Tyr is a pathogenic or benign variant. We consider it to be a variant of uncertain significance. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jul 08, 2022

The p.C559Y variant (also known as c.1676G>A), located in coding exon 4 of the MSH6 gene, results from a G to A substitution at nucleotide position 1676. The cysteine at codon 559 is replaced by tyrosine, an amino acid with highly dissimilar properties. This alteration has been identified to co-segregate with disease in one family in which the proband had been diagnosed with endometrial cancer at age 68 and her daughter had been diagnosed with ovarian cancer at age 41 (Suchy J et al. Clin Genet, 2006 Jul;70:68-70). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.30
CADD	Uncertain	25
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.96	.;.;D;D;.
Eigen	Pathogenic	0.77
Eigen_PC	Pathogenic	0.70
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	.;D;D;D;D
M_CAP	Uncertain	0.12	D
MetaRNN	Pathogenic	0.96	D;D;D;D;D
MetaSVM	Uncertain	-0.19	T
MutationAssessor	Pathogenic	4.1	.;.;H;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Pathogenic	0.84	D
PROVEAN	Pathogenic	-9.3	.;D;D;.;D
REVEL	Uncertain	0.64
Sift	Pathogenic	0.0	.;D;D;.;D
Sift4G	Pathogenic	0.0010	D;D;D;D;D
Polyphen		1.0	.;.;D;.;.
Vest4		0.86
MutPred		0.87		.;.;Gain of sheet (P = 0.0827);.;.;
MVP		0.84
ClinPred		1.0	D
GERP RS		4.5
Varity_R		0.99
gMVP		0.87

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: rs63750595; hg19: chr2-48026798;