rs267607725

Positions:

• chr3-37001039-G-A
• chr3-37001039-G-C

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PVS1 PM2

The NM_001167617.3(MLH1):​c.3G>A​(p.Met1?) variant causes a start lost 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).

• Frequency: Genomes: not found (cov: 32)
• Consequence: MLH1 NM_001167617.3 start_lost
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:3 U:1
• 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 Pathogenic. Variant got 10 ACMG points.

• PVS1: Start lost variant, no new inframe start found.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MLH1	NM_000249.4	c.292G>A	p.Gly98Ser	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.292G>A	p.Gly98Ser	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:3 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Hereditary cancer-predisposing syndrome Pathogenic:1 Uncertain:1

Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Dec 16, 2021	This missense variant replaces glycine with serine at codon 98 of the MLH1 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in an individual affected with Lynch syndrome (PMID: 18561205). This variant has shown segregation with MLH1-associated cancers in a family (communication with an external laboratory; ClinVar SCV000543593). This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Although there is a suspicion that this variant may have a pathogenic role, additional evidence is necessary to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Ambry Genetics	Jun 11, 2024	The p.G98S variant (also known as c.292G>A), located in coding exon 3 of the MLH1 gene, results from a G to A substitution at nucleotide position 292. The glycine at codon 98 is replaced by serine, an amino acid with similar properties. This variant has been identified in individuals meeting Amsterdam criteria and/or with tumors demonstrating high microsatellite instability (Tournier I et al. Hum. Mutat. 2008 Dec;29:1412-24; Borras E et al. Cancer Prev Res (Phila), 2017 Oct;10:580-587; Ambry internal data). Based on an internal structural analysis, this alteration blocks the ATP binding site (Ban C et al. Cell, 1999 Apr;97:85-97; Wu H et al. Acta Crystallogr F Struct Biol Commun, 2015 Aug;71:981-5). This variant was not reported in population-based cohorts in the Genome Aggregation Database (gnomAD). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Colorectal cancer, hereditary nonpolyposis, type 2 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Baylor Genetics

Dec 30, 2022

- -

Hereditary nonpolyposis colorectal neoplasms Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 09, 2024

This sequence change replaces glycine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 98 of the MLH1 protein (p.Gly98Ser). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Lynch syndrome (PMID: 18561205, 22290698; internal data). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 90128). Invitae Evidence Modeling incorporating data from in vitro experimental studies (internal data) indicates that this missense variant is expected to disrupt MLH1 function with a positive predictive value of 95%. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.59	D
BayesDel_noAF	Pathogenic	0.61
CADD	Pathogenic	33
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.96	D
Eigen	Uncertain	0.61
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Uncertain	0.27	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Uncertain	0.69	D
PrimateAI	Uncertain	0.72	T
PROVEAN	Pathogenic	-5.5	D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.91
MutPred		0.94		Gain of phosphorylation at G98 (P = 0.0573);
MVP		0.99
MPC		0.40
ClinPred		1.0	D
GERP RS		5.9
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.97
gMVP		0.93

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: rs267607725; hg19: chr3-37042530; COSMIC: COSV51617219;