3-36993638-G-T

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 4P and 1B. PM1PP3_ModerateBS1_Supporting

The NM_000249.4(MLH1):c.91G>T(p.Ala31Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000551 in 1,614,222 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. A31C) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000046 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000056 ( 0 hom. )

Consequence

MLH1
NM_000249.4 missense

Scores

Clinical Significance

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

Conservation

PhyloP100: 9.49

Publications

4 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: Uncertain_significance. The variant received 3 ACMG points.

PM1

In a hotspot region, there are 26 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 51 uncertain in NM_000249.4

PP3

MetaRNN computational evidence supports a deleterious effect, 0.935

BS1

Variant frequency is greater than expected in population mid. GnomAdExome4 allele frequency = 0.0000561 (82/1461864) while in subpopulation MID AF = 0.00173 (10/5768). AF 95% confidence interval is 0.00094. There are 0 homozygotes in GnomAdExome4. There are 50 alleles in the male GnomAdExome4 subpopulation. Median coverage is 31. This position passed quality control check. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000249.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
MLH1	NM_000249.4	MANE Select	c.91G>T	p.Ala31Ser	missense	Exon 1 of 19	NP_000240.1
MLH1	NM_001354628.2		c.91G>T	p.Ala31Ser	missense	Exon 1 of 18	NP_001341557.1
MLH1	NM_001354629.2		c.91G>T	p.Ala31Ser	missense	Exon 1 of 18	NP_001341558.1

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
MLH1	ENST00000231790.8	TSL:1 MANE Select	c.91G>T	p.Ala31Ser	missense	Exon 1 of 19	ENSP00000231790.3
MLH1	ENST00000456676.7	TSL:1	c.91G>T	p.Ala31Ser	missense	Exon 1 of 17	ENSP00000416687.3
MLH1	ENST00000413740.2	TSL:1	c.91G>T	p.Ala31Ser	missense	Exon 1 of 15	ENSP00000416476.2

Frequencies

GnomAD3 genomes

AF:

0.0000460

AC:

AN:

152240

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000654

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00316

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.000955

GnomAD2 exomes

AF:

0.0000836

AC:

AN:

251118

AF XY:

0.0000957

show subpopulations

Gnomad AFR exome

AF:

0.0000615

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000882

Gnomad OTH exome

AF:

0.000163

GnomAD4 exome

AF:

0.0000561

AC:

AN:

1461864

Hom.:

Cov.:

AF XY:

0.0000688

AC XY:

AN XY:

727236

show subpopulations

African (AFR)

AF:

0.000179

AC:

AN:

33480

American (AMR)

AF:

0.0000224

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26134

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.000232

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53404

Middle Eastern (MID)

AF:

0.00173

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.0000315

AC:

AN:

1112000

Other (OTH)

AF:

0.000166

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.477

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

AF:

0.0000459

AC:

AN:

152358

Hom.:

Cov.:

AF XY:

0.0000268

AC XY:

AN XY:

74504

show subpopulations

African (AFR)

AF:

0.0000240

AC:

AN:

41582

American (AMR)

AF:

0.0000653

AC:

AN:

15310

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5186

South Asian (SAS)

AF:

0.000207

AC:

AN:

4830

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10624

Middle Eastern (MID)

AF:

0.00340

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

68034

Other (OTH)

AF:

0.000945

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.504

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.000107

Hom.:

Bravo

AF:

0.0000529

ExAC

AF:

0.000107

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3478

EpiCase

AF:

0.000109

EpiControl

AF:

0.000178

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:5Benign:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Colorectal cancer, hereditary nonpolyposis, type 2

Uncertain:2

Mar 26, 2024

Genomic Medicine Center of Excellence, King Faisal Specialist Hospital and Research Centre

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Apr 28, 2017

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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.

Lynch syndrome

Uncertain:1

Jul 29, 2024

All of Us Research Program, National Institutes of Health

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This missense variant replaces alanine with serine at codon 31 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 not been reported in individuals affected with MLH1-related disorders in the literature. This variant has been identified in 22/282520 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:1

Mar 31, 2022

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The MLH1 c.91_92delinsTG; p.Ala31Cys variant (rs63749994) is reported in the medical literature in several individuals with Lynch syndrome (Auclair 2006, Drost 2010, Hardt 2011), some of whom also carried the MLH1 c.1360G>C; p.Gly454Arg variant of uncertain significance (Auclair 2006, Hardt 2011). The c.91_92delGCinsTG variant is also reported in ClinVar (Variation ID: 90442), and is found in the general population with an overall allele frequency of 0.0078% (22/282508 alleles) in the Genome Aggregation Database. The alanine at position 31 is highly conserved and computational algorithms (PolyPhen2, SIFT) predict a deleterious effect. This variant has reduced in vitro mismatch repair activity when compared to wild type, but still maintains significantly higher activity than known deleterious variants (Drost 2010). However, given the limited clinical and functional data, the significance of this variant is uncertain at this time. References: Auclair et al. Systematic mRNA analysis for the effect of MLH1 and MSH2 missense and silent mutations on aberrant splicing. Hum Mutat. 2006 ;27(2):145-154. PMID: 16395668. Drost et al. A cell-free assay for the functional analysis of variants of the mismatch repair protein MLH1. Hum Mutat. 2010;31(3):247-253. PMID: 20020535. Hardt et al. Missense variants in hMLH1 identified in patients from the German HNPCC consortium and functional studies. Fam Cancer. 2011;10(2):273-284. PMID: 21404117.

Hereditary cancer-predisposing syndrome

Uncertain:1

Mar 13, 2019

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The p.A31S variant (also known as c.91G>T), located in coding exon 1 of the MLH1 gene, results from a G to T substitution at nucleotide position 91. The alanine at codon 31 is replaced by serine, an amino acid with similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. In addition, this alteration is predicted to be deleterious by MAPP-MMR in silico analyses (Chao EC et al. Hum. Mutat. 2008 Jun;29:852-60). Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear.

Hereditary nonpolyposis colorectal neoplasms

Benign:1

Sep 03, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.47

BayesDel_addAF

Pathogenic

0.37

BayesDel_noAF

Pathogenic

0.60

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.90

Eigen

Pathogenic

0.74

Eigen_PC

Pathogenic

0.77

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Pathogenic

0.98

M_CAP

Pathogenic

0.64

MetaRNN

Pathogenic

0.94

MetaSVM

Uncertain

0.42

MutationAssessor

Pathogenic

4.3

PhyloP100

9.5

PrimateAI

Uncertain

0.75

PROVEAN

Uncertain

-2.5

REVEL

Pathogenic

0.93

Sift

Pathogenic

0.0

Sift4G

Uncertain

0.045

Polyphen

0.99

Vest4

0.75

MutPred

0.77

Loss of ubiquitination at K33 (P = 0.0795)

MVP

0.98

MPC

0.38

ClinPred

0.88

GERP RS

6.0

PromoterAI

-0.13

Neutral

(source)

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.6

Varity_R

0.96

gMVP

0.64

Mutation Taster

=18/82

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over