2-47783349-G-C

Position:

• chr2-47783349-G-C

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.116G>C​(p.Gly39Ala) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000687 in 1,456,160 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G39E) has been classified as Benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: MSH6 NM_000179.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:1
• Conservation: PhyloP100: 1.78

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 10 benign, 17 uncertain in NM_000179.3
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.2602535).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MSH6	NM_000179.3	c.116G>C	p.Gly39Ala	missense_variant	1/10	ENST00000234420.11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MSH6	ENST00000234420.11	c.116G>C	p.Gly39Ala	missense_variant	1/10	1	NM_000179.3	P4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000865 AC: 2 AN: 231236 Hom.: 0 AF XY: 0.00000784 AC XY: 1 AN XY: 127506

Gnomad AFR exome AF: 0.0000762

Gnomad AMR exome AF: 0.0000298

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.87e-7 AC: 1 AN: 1456160 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 724200

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000226

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ExAC AF: 0.00000849 AC: 1

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Lynch syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

All of Us Research Program, National Institutes of Health

Jun 26, 2023

This missense variant replaces glycine with alanine at codon 39 of the MSH6 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with MSH6-related disorders in the literature. This variant has been identified in 2/231236 chromosomes in the general population by the Genome Aggregation Database (gnomAD). 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 provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

May 16, 2016

This variant is denoted MSH6 c.116G>C at the cDNA level, p.Gly39Ala (G39A) at the protein level, and results in the change of a Glycine to an Alanine (GGG>GCG). This variant has not, to our knowledge, been published in the literature as pathogenic or benign. MSH6 Gly39Ala 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 Glycine and Alanine share similar properties, this is considered a conservative amino acid substitution. MSH6 Gly39Ala occurs at a position that is not conserved and is not located in a known functional domain (Kariola 2002, Terui 2013). In silico analyses are inconsistent regarding the effect this variant may have on protein structure and function. Based on currently available evidence, it is unclear whether MSH6 Gly39Ala 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

Feb 16, 2022

The p.G39A variant (also known as c.116G>C), located in coding exon 1 of the MSH6 gene, results from a G to C substitution at nucleotide position 116. The glycine at codon 39 is replaced by alanine, an amino acid with similar properties. This amino acid position is not 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. -

Hereditary nonpolyposis colorectal neoplasms Benign:1

Benign, criteria provided, single submitter

clinical testing

Invitae

Jul 07, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.071
BayesDel_addAF	Benign	-0.19	T
BayesDel_noAF	Benign	-0.32
CADD	Benign	17
DANN	Benign	0.62
DEOGEN2	Benign	0.26	.;T
Eigen	Benign	-0.58
Eigen_PC	Benign	-0.50
FATHMM_MKL	Benign	0.13	N
LIST_S2	Benign	0.65	T;T
M_CAP	Pathogenic	0.91	D
MetaRNN	Benign	0.26	T;T
MetaSVM	Benign	-0.59	T
MutationAssessor	Benign	0.69	N;N
MutationTaster	Benign	1.0	N;N
PrimateAI	Uncertain	0.74	T
PROVEAN	Benign	-0.10	N;N
REVEL	Benign	0.15
Sift	Benign	1.0	T;T
Sift4G	Benign	1.0	T;T
Polyphen		0.0	.;B
Vest4		0.20
MutPred		0.17		Loss of relative solvent accessibility (P = 0.0071);Loss of relative solvent accessibility (P = 0.0071);
MVP		0.84
ClinPred		0.064	T
GERP RS		2.6
RBP_binding_hub_radar		0.92
RBP_regulation_power_radar		2.7
Varity_R		0.082
gMVP		0.38

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: rs1042821; hg19: chr2-48010488;