rs876661197

Positions:

• chr2-47783481-C-A
• chr2-47783481-C-G
• chr2-47783481-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 4P and 2B. PM1 PM2 BP4_Moderate

The NM_000179.3(MSH6):​c.248C>A​(p.Ala83Asp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000156 in 1,279,656 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/20 in silico tools predict a benign 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. A83G) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000016 (0 hom.)
• Consequence: MSH6 NM_000179.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: 0.592

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 4 benign, 16 uncertain in NM_000179.3
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.24900463).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MSH6	NM_000179.3	c.248C>A	p.Ala83Asp	missense_variant	1/10	ENST00000234420.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MSH6	ENST00000234420.11	c.248C>A	p.Ala83Asp	missense_variant	1/10	1	NM_000179.3	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000156 AC: 2 AN: 1279656 Hom.: 0 Cov.: 34 AF XY: 0.00 AC XY: 0 AN XY: 621124

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: 0.00000195

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Lynch syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

All of Us Research Program, National Institutes of Health

Aug 15, 2023

- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Mar 22, 2016

This variant is denoted MSH6 c.248C>A at the cDNA level, p.Ala83Asp (A83D) at the protein level, and results in the change of an Alanine to an Aspartic Acid (GCT>GAT). This variant has not, to our knowledge, been published in the literature as pathogenic or benign. MSH6 Ala83Asp was not observed in approximately 4,900 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 Alanine and Aspartic Acid differ in polarity, charge, size or other properties, this is considered a non-conservative amino acid substitution. MSH6 Ala83Asp occurs at a position that is not conserved and is not located in a known functional domain (Kariola 2002, Terui 2013). In silico analyses predict that this variant is unlikely to alter protein structure or function. Based on currently available evidence, it is unclear whether MSH6 Ala83Asp is a pathogenic or benign variant. We consider it to be a variant of uncertain significance. -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Apr 01, 2023

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. 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 not expected to disrupt MSH6 protein function. ClinVar contains an entry for this variant (Variation ID: 419824). This variant has not been reported in the literature in individuals affected with MSH6-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces alanine, which is neutral and non-polar, with aspartic acid, which is acidic and polar, at codon 83 of the MSH6 protein (p.Ala83Asp). -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 30, 2024

The p.A83D variant (also known as c.248C>A), located in coding exon 1 of the MSH6 gene, results from a C to A substitution at nucleotide position 248. The alanine at codon 83 is replaced by aspartic acid, an amino acid with dissimilar properties. This amino acid position is well conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Endometrial carcinoma Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Baylor Genetics

Oct 10, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.18
BayesDel_addAF	Benign	-0.039	T
BayesDel_noAF	Benign	-0.29
CADD	Benign	16
DANN	Benign	0.85
DEOGEN2	Benign	0.25	T;T
Eigen	Benign	-0.88
Eigen_PC	Benign	-0.89
FATHMM_MKL	Benign	0.090	N
LIST_S2	Benign	0.61	T;T
M_CAP	Pathogenic	0.79	D
MetaRNN	Benign	0.25	T;T
MetaSVM	Benign	-0.67	T
MutationAssessor	Benign	0.55	N;.
MutationTaster	Benign	1.0	N;N
PrimateAI	Pathogenic	0.81	D
PROVEAN	Benign	-0.36	N;.
REVEL	Benign	0.071
Sift	Benign	0.13	T;.
Sift4G	Benign	0.086	T;T
Polyphen		0.073	B;.
Vest4		0.41
MutPred		0.23		Loss of MoRF binding (P = 0.0626);.;
MVP		0.68
ClinPred		0.085	T
GERP RS		2.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.3
Varity_R		0.11
gMVP		0.36

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: rs876661197; hg19: chr2-48010620;