3-37000976-T-G

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1PM2PM5PP3_Strong

The NM_000249.4(MLH1):c.229T>G(p.Cys77Gly) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000138 in 1,451,990 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 Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C77S) has been classified as Likely pathogenic.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

MLH1
NM_000249.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:3

Conservation

PhyloP100: 7.56

Publications

21 publications found

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 Gene-Disease associations (from GenCC):

Lynch syndrome
Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: G2P, ClinGen, Orphanet
Lynch syndrome 2
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Genomics England PanelApp
Muir-Torre syndrome
Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Genomics England PanelApp, Ambry Genetics, G2P, Orphanet
mismatch repair cancer syndrome 1
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Ambry Genetics, G2P, Labcorp Genetics (formerly Invitae), Orphanet, ClinGen
Lynch syndrome 1
Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
ovarian cancer
Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
malignant pancreatic neoplasm
Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
rhabdomyosarcoma
Inheritance: AR Classification: MODERATE Submitted by: Genomics England PanelApp
prostate cancer
Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
breast cancer
Inheritance: AD Classification: NO_KNOWN Submitted by: Ambry Genetics
hereditary breast carcinoma
Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

MLH1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 10 ACMG points.

PM1

In a hotspot region, there are 13 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 45 uncertain in NM_000249.4

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr3-37000977-G-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 422226.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.962

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4 link	c.229T>G	p.Cys77Gly	missense_variant	Exon 3 of 19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8 link	c.229T>G	p.Cys77Gly	missense_variant	Exon 3 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

0.00000138

AC:

AN:

1451990

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

723074

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33290

American (AMR)

AF:

0.00

AC:

AN:

44706

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26058

East Asian (EAS)

AF:

0.00

AC:

AN:

39580

South Asian (SAS)

AF:

0.00

AC:

AN:

86018

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53400

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5748

European-Non Finnish (NFE)

AF:

0.00000181

AC:

AN:

1103108

Other (OTH)

AF:

0.00

AC:

AN:

60082

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.600

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

Cov.:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Muir-Torré syndrome;C1333991:Colorectal cancer, hereditary nonpolyposis, type 2;C5399763:Mismatch repair cancer syndrome 1

Uncertain:1

Feb 04, 2022

Fulgent Genetics, Fulgent Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Hereditary nonpolyposis colorectal neoplasms

Uncertain:1

Dec 05, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces cysteine, which is neutral and slightly polar, with glycine, which is neutral and non-polar, at codon 77 of the MLH1 protein (p.Cys77Gly). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with MLH1-related conditions. ClinVar contains an entry for this variant (Variation ID: 642117). 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 with a positive predictive value of 95%. Experimental studies are conflicting or provide insufficient evidence to determine the effect of this variant on MLH1 function (PMID: 15475387). This variant disrupts the p.Cys77 amino acid residue in MLH1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 9032648, 15849733, 17510385, 21404117). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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.

Hereditary cancer-predisposing syndrome

Uncertain:1

Oct 15, 2024

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The p.C77G variant (also known as c.229T>G), located in coding exon 3 of the MLH1 gene, results from a T to G substitution at nucleotide position 229. The cysteine at codon 77 is replaced by glycine, an amino acid with highly dissimilar properties. This variant was identified in a yeast-based functional genetic screen and demonstrated partial loss of relative mismatch repair activity (Ellison AR et al. Nucleic Acids Res., 2004 Oct;32:5321-38). Based on an internal structural analysis using a published crystal structure, this variant is anticipated to result in disruption of the ATP binding site (Wu H et al. Acta Crystallogr F Struct Biol Commun, 2015 Aug;71:981-5). 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 available evidence, the clinical significance of this variant remains unclear.

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.71

BayesDel_addAF

Pathogenic

0.52

BayesDel_noAF

Pathogenic

0.51

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

DEOGEN2

Uncertain

0.78

Eigen

Uncertain

0.56

Eigen_PC

Uncertain

0.61

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Uncertain

0.96

M_CAP

Uncertain

0.22

MetaRNN

Pathogenic

0.96

MetaSVM

Uncertain

-0.11

MutationAssessor

Uncertain

2.3

PhyloP100

7.6

PrimateAI

Pathogenic

0.81

PROVEAN

Pathogenic

-10

REVEL

Pathogenic

0.94

Sift

Pathogenic

0.0

Sift4G

Pathogenic

0.0

Vest4

0.91

ClinPred

1.0

GERP RS

5.9

Varity_R

0.97

gMVP

0.86

Mutation Taster

=3/97

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.060

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over