3-37008899-T-G

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PP3_Strong

The NM_000249.4(MLH1):c.539T>G(p.Val180Gly) variant causes a missense change. The variant allele was found at a frequency of 0.0000509 in 1,612,084 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic 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. V180A) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000026 (0 hom., cov: 31)
  • Exomes 𝑓: 0.000053 (0 hom.)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:11 B:1
• Conservation: PhyloP100: 5.40

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 15 uncertain in NM_000249.4
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.94

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MLH1	NM_000249.4	c.539T>G	p.Val180Gly	missense_variant	6/19	ENST00000231790.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MLH1	ENST00000231790.8	c.539T>G	p.Val180Gly	missense_variant	6/19	1	NM_000249.4	P1

Frequencies

GnomAD3 genomes AF: 0.0000263 AC: 4 AN: 152198 Hom.: 0 Cov.: 31

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000441

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000437 AC: 11 AN: 251434 Hom.: 0 AF XY: 0.0000368 AC XY: 5 AN XY: 135892

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000578

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: 0.0000791

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000534 AC: 78 AN: 1459886 Hom.: 0 Cov.: 30 AF XY: 0.0000454 AC XY: 33 AN XY: 726446

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000671

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: 0.0000658

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome AF: 0.0000263 AC: 4 AN: 152198 Hom.: 0 Cov.: 31 AF XY: 0.0000134 AC XY: 1 AN XY: 74366

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.0000655

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000441

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000564 Hom.: 0

Bravo AF: 0.0000189

ExAC AF: 0.0000330 AC: 4

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:11 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Colorectal cancer, hereditary nonpolyposis, type 2 Uncertain:3 Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Apr 27, 2017	This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -
Uncertain significance, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 15, 2020	This variant was determined to be of uncertain significance according to ACMG Guidelines, 2015 [PMID:25741868]. -
Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Sep 29, 2016	- -
Likely benign, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Mar 15, 2023	This variant is considered likely benign. This variant is strongly associated with less severe personal and family histories of cancer, typical for individuals without pathogenic variants in this gene [PMID: 25085752]. -

not provided Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	May 04, 2023	The frequency of this variant in the general population, 0.000079 (9/113724 chromosomes, http://gnomad.broadinstitute.org), is uninformative in assessment of its pathogenicity. In the published literature, the variant has been reported in individuals with suspected Lynch syndrome (PMID: 18566915 (2009), 25648859 (2015)), endometrial cancer (PMID: 14645426 (2003)) and pancreatic cancer (PMID: 28767289 (2017)). Published functional studies found this variant to have an intermediate effect on attenuating mismatch repair (MMR) function (PMID: 31784484 (2019)). Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded predictions that this variant is damaging. Based on the available information, we are unable to determine the clinical significance of this variant. -
Uncertain significance, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Nov 01, 2020	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	May 18, 2023	In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Observed in individuals with a personal or family history including endometrial, colorectal, pancreatic, and other cancers (Berends et al., 2003; Nilbert et al., 2009; Therkildsen et al., 2015; Shindo et al., 2017; Hu et al., 2020); Published functional studies demonstrate intermediate effects on microsatellite instability and mutation accumulation (Houlleberghs et al., 2020); This variant is associated with the following publications: (PMID: 18566915, 14645426, 25648859, 26333163, 17192056, 28767289, 31391288, 32659497, 22753075, 36461907, 31784484) -

Hereditary cancer-predisposing syndrome Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Nov 06, 2023	This missense variant replaces valine with glycine at codon 180 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 individuals affected with Lynch syndrome (PMID: 18566915, 25648859), endometrial cancer (PMID: 14645426), breast/ovarian cancer (PMID: 34359559), or pancreatic cancer (PMID: 28767289). This variant has been identified in 11/251434 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	Jan 26, 2023	The p.V180G variant (also known as c.539T>G), located in coding exon 6 of the MLH1 gene, results from a T to G substitution at nucleotide position 539. The valine at codon 180 is replaced by glycine, an amino acid with dissimilar properties. This alteration has been reported in one individual with MSI-L endometrial cancer with absent MLH1 on IHC and one individual with pancreatic cancer (Berends MJ et al. J. Clin. Oncol. 2003 Dec;21:4364-70; Shindo K et al. J. Clin. Oncol. 2017 Oct;35(30):3382-3390)). In addition, p.V180G was detected in the Danish HNPCC registry in conjunction with a pathogenic MSH2 mutation in an individual with glioblastoma (Therkildsen C et al. Eur. J. Neurol. 2015 Apr;22(4):717-24). This alteration has been classified as a variant of unknown significance using the following lines of evidence: in silico prediction models, segregation with disease, clinical phenotype including tumor characteristics, mutation co-occurrence, and functional studies (Thompson BA et al. Hum. Mutat. 2013 Jan;34:200-9; Thompson BA et al. Nat. Genet. 2014 Feb;46:107-15; available at [www.insight-group.org/variants/classifications/]). 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. -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Center for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital

Feb 06, 2024

- -

Lynch syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

All of Us Research Program, National Institutes of Health

Feb 05, 2024

This missense variant replaces valine with glycine at codon 180 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 individuals affected with Lynch syndrome (PMID: 18566915, 25648859), endometrial cancer (PMID: 14645426), breast/ovarian cancer (PMID: 34359559), or pancreatic cancer (PMID: 28767289). This variant has been identified in 11/251434 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. -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Oct 20, 2022

This sequence change replaces valine, which is neutral and non-polar, with glycine, which is neutral and non-polar, at codon 180 of the MLH1 protein (p.Val180Gly). This variant is present in population databases (rs63750102, gnomAD 0.008%). This missense change has been observed in individual(s) with clinical features of Lynch syndrome (PMID: 14645426, 18566915, 25648859, 28767289). ClinVar contains an entry for this variant (Variation ID: 90257). 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. Experimental studies are conflicting or provide insufficient evidence to determine the effect of this variant on MLH1 function (PMID: 31784484). 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.66
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.46
Cadd	Pathogenic	28
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.87	D;.;D
Eigen	Pathogenic	0.97
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;D;T
M_CAP	Uncertain	0.21	D
MetaRNN	Pathogenic	0.94	D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.7	H;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D
PrimateAI	Uncertain	0.61	T
PROVEAN	Pathogenic	-5.9	D;D;D
REVEL	Pathogenic	0.91
Sift	Uncertain	0.0010	D;D;D
Sift4G	Pathogenic	0.0010	D;D;D
Polyphen		1.0	D;.;.
Vest4		0.69
MutPred		0.79		Loss of stability (P = 0.0122);.;.;
MVP		0.96
MPC		0.43
ClinPred		0.99	D
GERP RS		6.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.92
gMVP		0.91

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: rs63750102; hg19: chr3-37050390;