rs200076893

Positions:

chr3-37004470-T-A

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM1PP3

The NM_000249.4(MLH1):c.376T>A(p.Tyr126Asn) variant causes a missense change. The variant allele was found at a frequency of 0.0000521 in 1,613,682 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. Y126H) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000039 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000053 ( 0 hom. )

Consequence

MLH1
NM_000249.4 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:9B:1

Conservation

PhyloP100: 5.96

Variant links:

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]

MLH1 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 3 ACMG points.

PM1

In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 16 uncertain in NM_000249.4

PP3

MetaRNN computational evidence supports a deleterious effect, 0.835

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MLH1	NM_000249.4 linkuse as main transcript	c.376T>A	p.Tyr126Asn	missense_variant	4/19	ENST00000231790.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MLH1	ENST00000231790.8 linkuse as main transcript	c.376T>A	p.Tyr126Asn	missense_variant	4/19	1	NM_000249.4	P1	P40692-1

Frequencies

GnomAD3 genomes

AF:

0.0000394

AC:

AN:

152244

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

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:

0.0000735

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000398

AC:

AN:

251404

Hom.:

AF XY:

0.0000515

AC XY:

AN XY:

135864

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

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:

0.0000880

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000534

AC:

AN:

1461320

Hom.:

Cov.:

AF XY:

0.0000481

AC XY:

AN XY:

727014

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000447

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:

0.0000621

Gnomad4 OTH exome

AF:

0.000116

GnomAD4 genome

AF:

0.0000394

AC:

AN:

152362

Hom.:

Cov.:

AF XY:

0.0000268

AC XY:

AN XY:

74508

show subpopulations

Gnomad4 AFR

AF:

0.0000240

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000735

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000694

Hom.:

Bravo

AF:

0.0000491

ExAC

AF:

0.0000741

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:9Benign:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Colorectal cancer, hereditary nonpolyposis, type 2

Uncertain:2Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 27, 2024	- -
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]. -
Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Sep 30, 2016	- -

not provided

Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Jul 02, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Apr 22, 2024	Observed in individuals with colorectal cancer, breast cancer, endometrial cancer, and/or polyps (PMID: 24383517, 30998989, 35475445, 35430768); Published functional studies demonstrate no damaging effect: variant classified as not pathogenic based on cell survival assay (PMID: 30998989); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 24383517, 27527004, 22290698, 18561205, 26333163, 26659599, 22788692, 16451135, 22753075, 35430768, 35475445, 30998989) -

Hereditary cancer-predisposing syndrome

Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Feb 15, 2023	This missense variant replaces tyrosine with asparagine at codon 126 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). A functional study has shown that this variant does not affect MLH1 protein function in a methylation tolerance-based assay (PMID: 30998989). This variant has been observed in an individual affected with colorectal cancer and a Lynch syndrome family (PMID: 18561205, 24383517). This variant has been identified in 11/282808 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	Jun 03, 2024	The p.Y126N variant (also known as c.376T>A), located in coding exon 4 of the MLH1 gene, results from a T to A substitution at nucleotide position 376. The tyrosine at codon 126 is replaced by asparagine, an amino acid with dissimilar properties. This alteration has been reported as an uncertain variant in a proband diagnosed with colon cancer at age <50 years, whose family history met Amsterdam II criteria. In addition, the proband's tumor was MSI-H and demonstrated loss of MLH1 by immunohistochemistry (IHC; Stigliano V et al. J Exp Clin Cancer Res. 2014 Jan; 33:1). This alteration was reported in another proband with a personal history of endometrial cancer, undergoing genetic testing due to a clinical suspicion of Lynch syndrome. The proband's tumor was MSI-H and demonstrated loss of MLH1 and PMS2 by IHC (Liccardo R et al. Int J Mol Med, 2022 Jun;49:). However, this variant has been detected in multiple individuals with no reported features of Lynch syndrome. This amino acid position is well 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. -

Breast and/or ovarian cancer

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Jun 08, 2022

- -

Lynch syndrome

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

All of Us Research Program, National Institutes of Health

Dec 01, 2023

This missense variant replaces tyrosine with asparagine at codon 126 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). A functional study has shown that this variant does not affect MLH1 protein function in a methylation tolerance-based assay (PMID: 30998989). This variant has been observed in an individual affected with colorectal cancer and a Lynch syndrome family (PMID: 18561205, 24383517). This variant has been identified in 11/282808 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

Labcorp Genetics (formerly Invitae), Labcorp

Jan 31, 2024

This sequence change replaces tyrosine, which is neutral and polar, with asparagine, which is neutral and polar, at codon 126 of the MLH1 protein (p.Tyr126Asn). This variant is present in population databases (rs200076893, gnomAD 0.009%). This missense change has been observed in individual(s) with clinical features of Lynch syndrome (PMID: 18561205, 24383517, 30998989). ClinVar contains an entry for this variant (Variation ID: 90184). An algorithm developed specifically for the MLH1 gene suggests that this missense change is likely to be deleterious (PMID: 22290698). Experimental studies have shown that this missense change does not substantially affect MLH1 function (PMID: 30998989). 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

Uncertain

0.45

BayesDel_addAF

Pathogenic

0.23

BayesDel_noAF

Pathogenic

0.30

CADD

Pathogenic

DANN

Uncertain

0.99

DEOGEN2

Uncertain

0.80

D;.;T

Eigen

Pathogenic

0.74

Eigen_PC

Pathogenic

0.73

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Uncertain

0.96

D;D;D

M_CAP

Pathogenic

0.39

MetaRNN

Pathogenic

0.84

D;D;D

MetaSVM

Pathogenic

1.0

MutationAssessor

Uncertain

2.3

M;.;.

MutationTaster

Benign

1.0

D;D;D;D;D;D

PrimateAI

Uncertain

0.73

PROVEAN

Pathogenic

-7.7

D;D;D

REVEL

Pathogenic

0.76

Sift

Pathogenic

0.0

D;D;D

Sift4G

Pathogenic

0.0

D;D;D

Polyphen

0.91

P;.;.

Vest4

0.90

MVP

0.94

MPC

0.46

ClinPred

0.69

GERP RS

6.0

Varity_R

0.96

gMVP

0.90

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over