3-37028794-C-T

Position:

chr3-37028794-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM5

The NM_000249.4(MLH1):c.1420C>T(p.Arg474Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000991 in 1,613,982 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. R474G) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000096 ( 0 hom. )

Consequence

MLH1
NM_000249.4 missense

Scores

Clinical Significance

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

Conservation

PhyloP100: 1.54

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 2 ACMG points.

PM5

Other missense variant is known to change same aminoacid residue: Variant chr3-37028795-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MLH1	NM_000249.4 linkuse as main transcript	c.1420C>T	p.Arg474Trp	missense_variant	13/19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8 linkuse as main transcript	c.1420C>T	p.Arg474Trp	missense_variant	13/19	1	NM_000249.4	ENSP00000231790	P1	P40692-1

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152120

Hom.:

Cov.:

show subpopulations

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000239

AC:

AN:

251410

Hom.:

AF XY:

0.00000736

AC XY:

AN XY:

135870

show subpopulations

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:

0.0000980

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000880

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000958

AC:

AN:

1461862

Hom.:

Cov.:

AF XY:

0.00000963

AC XY:

AN XY:

727242

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:

0.0000348

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00000719

Gnomad4 OTH exome

AF:

0.0000166

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152120

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74288

show subpopulations

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:

0.0000147

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.00000992

Hom.:

ExAC

AF:

0.0000165

AC:

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:2

Uncertain significance, criteria provided, single submitter	clinical testing	Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center	Sep 22, 2024	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Baylor Genetics	Feb 24, 2024	- -

Lynch syndrome

Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	University of Washington Department of Laboratory Medicine, University of Washington	May 01, 2018	MLH1 NM_000249.3:c.1420C>T has a 59.6% probability of pathogenicity based on combining prior probability from public data with a likelihood ratio of 0.16 to 1, generated from evidence of seeing this as a somatic mutation in a tumor with loss of heterozygosity at the MLH1 locus. See Shirts et al 2018, PMID 29887214. -
Uncertain significance, criteria provided, single submitter	clinical testing	All of Us Research Program, National Institutes of Health	Jan 11, 2024	This missense variant replaces arginine with tryptophan at codon 474 of the MLH1 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). This variant has been reported to have no impact on splicing and on MLH1 function based on a methylation tolerance assay (PMID: 18561205, 30998989). This variant has been reported in InSiGHT and Leiden Open Variations Databases. This variant has been identified in 7/282820 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:2

Uncertain significance, criteria provided, single submitter	clinical testing	PreventionGenetics, part of Exact Sciences	Dec 22, 2016	- -
Uncertain significance, no assertion criteria provided	clinical testing	Department of Pathology and Laboratory Medicine, Sinai Health System	-	The MLH1 p.Arg474Trp variant was not identified in the literature nor was it identified in the COGR, MutDB, UMD-LSDB, and in the Zhejiang Colon Cancer Databases. The variant was identified in dbSNP (ID: rs147939838) as with Uncertain significance allele; in the ClinVar database as uncertain significance by InSiGHT; 1X in the Cosmic database from a carcinoma of the large intestine with a confirmed somatic status; 1X in the Insight Colon Cancer Gene Variant database with unknown significance, 1X in the Mismatch Repair Genes Variant Database, and listed 8X in the Insight Hereditary Tumors database. The variant was also identified in the 1000 Genomes Project in 2 of 5000 chromosomes (frequency: 0.0004) and in the NHLBI GO Exome Sequencing Project in 7 of 4406 African American alleles. In addition, the variant was identified in control databases in 7 of 277168 chromosomes at a frequency of 0.00003 (Genome Aggregation Database Feb 27, 2017). It was observed in the following populations: Latino in 3 of 34420 chromosomes (freq: 0.00009), European Non-Finnish in 1 of 126660 chromosomes (freq: 0.000008), and South Asian in 3 of 30782 chromosomes (freq: 0.0001); it was seen in the African, Other, Ashkenazi Jewish, East Asian, European Finnish populations. An exon inclusion functional study was performed, where the variant was amplified by PCR along with 150bp flanking sequences and inserted into a splicing reporter mini-gene. After transfection into HeLa cells, effects of splicing were evaluated. The p.Arg474Trp variant showed no effect (Tournier 2008). The p.Arg474 residue is conserved in mammals but not in more distantly related organisms however computational analyses (PolyPhen-2, SIFT, AlignGVGD, BLOSUM, MutationTaster) do not suggest a high likelihood of impact to the protein; this information is not predictive enough to rule out 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 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:2

Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Feb 15, 2021	This missense variant replaces arginine with tryptophan at codon 474 of the MLH1 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). This variant has been reported to have no impact on splicing and on MLH1 function based on a methylation tolerance assay (PMID: 18561205, 30998989). This variant has been reported in InSiGHT and Leiden Open Variations Databases. This variant has been identified in 7/282820 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	Dec 01, 2022	The p.R474W variant (also known as c.1420C>T), located in coding exon 13 of the MLH1 gene, results from a C to T substitution at nucleotide position 1420. The arginine at codon 474 is replaced by tryptophan, an amino acid with dissimilar properties. This variant demonstrated no effect on splicing in one ex vivo assay (Tournier I et al. Hum. Mutat. 2008 Dec;29:1412-24). This variant was also observed in 1/3251 individuals who met eligibility criteria for hereditary breast and ovarian cancer syndrome (Lerner-Ellis J et al. J Cancer Res Clin Oncol, 2021 Mar;147:871-879). 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

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

May 30, 2024

Variant summary: MLH1 c.1420C>T (p.Arg474Trp) results in a non-conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 2.4e-05 in 251410 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.1420C>T has been reported in the literature in individuals affected with breast cancer (Pramanik_2024), but was also found in controls (Dorling_2021). These reports do not provide unequivocal conclusions about association of the variant with Lynch Syndrome. In functional studies the variant was found to have no effect on RNA splicing (Tournier_2008), and mismatch repair activity (Bouvet_2019). The following publications have been ascertained in the context of this evaluation (PMID: 30998989, 18561205, 38439815, 33471991). ClinVar contains an entry for this variant (Variation ID: 89735). Based on the evidence outlined above, the variant was classified as VUS-possibly benign. -

Hereditary nonpolyposis colorectal neoplasms

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 04, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.11

BayesDel_addAF

Pathogenic

0.27

BayesDel_noAF

Pathogenic

0.35

CADD

Pathogenic

DANN

Pathogenic

1.0

DEOGEN2

Uncertain

0.56

D;.;.;.;.;.;T;T

Eigen

Uncertain

0.35

Eigen_PC

Uncertain

0.40

FATHMM_MKL

Uncertain

0.76

LIST_S2

Uncertain

0.91

D;D;.;.;.;D;D;D

M_CAP

Uncertain

0.092

MetaRNN

Uncertain

0.44

T;T;T;T;T;T;T;T

MetaSVM

Uncertain

-0.25

MutationAssessor

Uncertain

2.6

M;.;.;.;.;.;.;.

MutationTaster

Benign

1.0

D;D;D;D;D;D

PrimateAI

Uncertain

0.54

PROVEAN

Uncertain

-2.8

D;D;D;D;D;D;D;D

REVEL

Uncertain

0.62

Sift

Uncertain

0.0020

D;D;D;D;D;D;D;D

Sift4G

Uncertain

0.021

D;D;D;D;D;D;D;D

Polyphen

0.99

D;.;.;.;.;.;.;.

Vest4

0.52

MutPred

0.36

Loss of MoRF binding (P = 0.0865);.;.;.;.;.;.;.;

MVP

0.94

MPC

0.070

ClinPred

0.63

GERP RS

5.1

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.46

gMVP

0.39

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