rs34213726

Positions:

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 4P and 1B. PM1PM2BP4

The NM_000249.4(MLH1):c.1327A>C(p.Lys443Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000186 in 1,614,022 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 31)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

MLH1
NM_000249.4 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:5B:1

Conservation

PhyloP100: -0.291

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 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 3 benign, 16 uncertain in NM_000249.4

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (MetaRNN=0.27116066).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MLH1	NM_000249.4 linkuse as main transcript	c.1327A>C	p.Lys443Gln	missense_variant	12/19	ENST00000231790.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MLH1	ENST00000231790.8 linkuse as main transcript	c.1327A>C	p.Lys443Gln	missense_variant	12/19	1	NM_000249.4	P1	P40692-1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152136

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD4 exome

AF:

0.00000137

AC:

AN:

1461886

Hom.:

Cov.:

AF XY:

0.00000275

AC XY:

AN XY:

727244

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

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:

0.00000180

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152136

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74320

show subpopulations

Gnomad4 AFR

AF:

0.00

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:

0.0000147

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000689

Hom.:

Bravo

AF:

0.00000378

ExAC

AF:

0.00000824

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:5Benign:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Hereditary cancer-predisposing syndrome

Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	May 21, 2024	The p.K443Q variant (also known as c.1327A>C), located in coding exon 12 of the MLH1 gene, results from an A to C substitution at nucleotide position 1327. The lysine at codon 443 is replaced by glutamine, an amino acid with similar properties. This alteration was detected in a patient with a MSI-High colorectal cancer (CRC) that showed loss of MLH1 and PMS2 on IHC, and another patient with CRC that showed loss of MLH1 on IHC (Hampel, H et al. N Engl J Med. 2005 May 5;352(18):1851-60; Drost M, Hum. Mutat. 2010 Mar; 31(3):247-53). However, multiple studies have shown normal MLH1 functional activity (Raevaara TE, Gastroenterology 2005 Aug; 129(2):537-49; Andersen SD, Hum. Mutat. 2012 Dec; 33(12):1647-55; Drost M, Hum. Mutat. 2010 Mar; 31(3):247-53). This amino acid position is poorly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Based on the available evidence, the clinical significance of this variant remains unclear. -
Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Mar 02, 2023	This missense variant replaces lysine with glutamine at codon 443 of the MLH1 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). Functional studies using recombinant human cells or cell-free assays reported that this variant has mismatch repair activity, localization, and expression comparable to wild type (PMID: 16083711, 20020535). This variant has been reported in individuals affected with Lynch syndrome (PMID: 15872200, 16083711, 22753075) and in an individual affected with gastric cancer (PMID: 15099349). This variant has been identified in 1/31370 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. -

Lynch syndrome 1

Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

Pathway Genomics

Jul 24, 2014

- -

Lynch syndrome

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

All of Us Research Program, National Institutes of Health

Aug 08, 2023

This missense variant replaces lysine with glutamine at codon 443 of the MLH1 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). Functional studies using recombinant human cells or cell-free assays reported that this variant has mismatch repair activity, localization, and expression comparable to wild type (PMID: 16083711, 20020535). This variant has been reported in individuals affected with Lynch syndrome (PMID: 15872200, 16083711, 22753075) and in an individual affected with gastric cancer (PMID: 15099349). This variant has been identified in 1/31370 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

Nov 14, 2023

This sequence change replaces lysine, which is basic and polar, with glutamine, which is neutral and polar, at codon 443 of the MLH1 protein (p.Lys443Gln). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with colorectal cancer and gastric cancer (PMID: 15099349, 15872200, 16083711). ClinVar contains an entry for this variant (Variation ID: 89698). 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 not expected to disrupt MLH1 protein function with a negative predictive value of 95%. Experimental studies have shown that this missense change does not substantially affect MLH1 function (PMID: 16083711, 20020535, 21136174, 22753075). 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. -

not provided

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

GeneDx

Apr 01, 2019

This variant is associated with the following publications: (PMID: 24933000, 17594722, 22753075, 21120944, 16083711, 21136174, 22949387, 17192056, 20020535, 22045683, 15872200) -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.074

BayesDel_addAF

Uncertain

0.16

BayesDel_noAF

Uncertain

-0.010

CADD

Benign

0.17

DANN

Benign

0.27

DEOGEN2

Benign

0.30

T;.;.;.;.;.

Eigen

Benign

-1.2

Eigen_PC

Benign

-1.2

FATHMM_MKL

Benign

0.28

LIST_S2

Benign

0.58

T;T;.;.;.;T

M_CAP

Benign

0.075

MetaRNN

Benign

0.27

T;T;T;T;T;T

MetaSVM

Benign

-0.61

MutationAssessor

Benign

1.4

L;.;.;.;.;.

MutationTaster

Benign

1.0

N;N;N;N;N;N

PrimateAI

Benign

0.25

PROVEAN

Benign

-0.40

N;N;N;N;N;N

REVEL

Uncertain

0.57

Sift

Benign

0.58

T;T;T;T;T;T

Sift4G

Benign

0.62

T;T;T;T;T;T

Polyphen

0.022

B;.;.;.;.;.

Vest4

0.72

MutPred

0.70

Loss of ubiquitination at K443 (P = 0.0014);.;.;.;.;.;

MVP

1.0

MPC

0.073

ClinPred

0.034

GERP RS

-0.74

Varity_R

0.036

gMVP

0.18

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