chr3-37001040-G-A

Position:

• chr3-37001040-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2 PM5 PP5

The NM_000249.4(MLH1):​c.293G>A​(p.Gly98Asp) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. G98A) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:3
• Conservation: PhyloP100: 9.42

Genes affected

MLH1 (HGNC:7127): (mutL homolog 1) The protein encoded by this gene can heterodimerize with mismatch repair endonuclease PMS2 to form MutL alpha, part of the DNA mismatch repair system. When MutL alpha is bound by MutS beta and some accessory proteins, the PMS2 subunit of MutL alpha introduces a single-strand break near DNA mismatches, providing an entry point for exonuclease degradation. The encoded protein is also involved in DNA damage signaling and can heterodimerize with DNA mismatch repair protein MLH3 to form MutL gamma, which is involved in meiosis. This gene was identified as a locus frequently mutated in hereditary nonpolyposis colon cancer (HNPCC). [provided by RefSeq, Aug 2017]

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr3-37001040-G-C is described in Lovd as [Likely_pathogenic].
• PP5: Variant 3-37001040-G-A is Pathogenic according to our data. Variant chr3-37001040-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 218023.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Likely_pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MLH1	NM_000249.4	c.293G>A	p.Gly98Asp	missense_variant	3/19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.293G>A	p.Gly98Asp	missense_variant	3/19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 28

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:3

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Hereditary nonpolyposis colorectal neoplasms Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jun 16, 2023

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant disrupts the p.Gly98 amino acid residue in MLH1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 22290698, 185612205; Invitae). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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 MLH1 protein function. ClinVar contains an entry for this variant (Variation ID: 218023). This missense change has been observed in individual(s) with Lynch syndrome (PMID: 20459533). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with aspartic acid, which is acidic and polar, at codon 98 of the MLH1 protein (p.Gly98Asp). -

not specified Uncertain:1

Uncertain significance, no assertion criteria provided

research

Mayo Clinic Laboratories, Mayo Clinic

-

- -

Carcinoma of colon Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

Department of Pathology and Laboratory Medicine, Sinai Health System

-

The MLH1 p.Gly98Asp variant was not identified in the literature nor was it identified in the dbSNP, COSMIC, “Mismatch Repair Genes Variant Database”, “MMR Gene Unclassified Variants Database”, InSiGHT Colon Cancer Gene Variant Database (LOVD), Zhejiang Colon Cancer Database (LOVD), GeneInsight - COGR database, UMD, NHLBI GO Exome Sequencing Project and the Exome Aggregation Consortium database (August 8, 2016). This variant was identified in the Clinvitae database (classified as uncertain significance by ClinVar), ClinVar database (classified as uncertain significance by Mayo Clinic) and LOVD - human mismatch repair genes databases. The p.Gly98 residue is conserved across mammals and other organisms, and four out of four computational analyses (PolyPhen-2, SIFT, AlignGVGD, BLOSUM) suggest that the c.293G>A variant may impact the protein; however, this information is not predictive enough to assume pathogenicity. The variant occurs outside of the splicing consensus sequence and in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer, HumanSpliceFinder) do not predict a greater than 10% difference in splicing. In summary, based on the above information, the clinical significance of this variant cannot be determined with certainty at this time. This variant is classified as a variant of uncertain significance. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 18, 2019

The p.G98D variant (also known as c.293G>A), located in coding exon 3 of the MLH1 gene, results from a G to A substitution at nucleotide position 293. The glycine at codon 98 is replaced by aspartic acid, an amino acid with similar properties. 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	1.0
BayesDel_addAF	Pathogenic	0.36	D
BayesDel_noAF	Pathogenic	0.61
CADD	Pathogenic	32
DANN	Uncertain	1.0
DEOGEN2	Benign	0.12	.;T
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.33	T;T
M_CAP	Uncertain	0.20	D
MetaRNN	Uncertain	0.73	D;D
MetaSVM	Pathogenic	0.90	D
PROVEAN	Benign	0.15	N;N
REVEL	Uncertain	0.53
Sift	Pathogenic	0.0	D;D
Sift4G	Benign	0.28	T;D
Vest4		0.59
MVP		0.95
ClinPred		1.0	D
GERP RS		5.9
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs863225382; hg19: chr3-37042531;