3-37020353-A-G

Variant names:

• chr3-37020353-A-G
• rs779581111
• NM_000249.4:c.928A>G

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM1 PP3_Moderate

The NM_000249.4(MLH1):​c.928A>G​(p.Thr310Ala) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000684 in 1,461,890 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. T310K) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000068 (0 hom.)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:9 B:2
• Conservation: PhyloP100: 8.88
• Publications: 5 publications found

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

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM1: In a hotspot region, there are 11 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 40 uncertain in NM_000249.4
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.87

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MLH1	NM_000249.4	MANE Select	c.928A>G	p.Thr310Ala	missense	Exon 11 of 19	NP_000240.1
	MLH1	NM_001354628.2		c.928A>G	p.Thr310Ala	missense	Exon 11 of 18	NP_001341557.1
	MLH1	NM_001354629.2		c.829A>G	p.Thr277Ala	missense	Exon 10 of 18	NP_001341558.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MLH1	ENST00000231790.8	TSL:1 MANE Select	c.928A>G	p.Thr310Ala	missense	Exon 11 of 19	ENSP00000231790.3
	MLH1	ENST00000456676.7	TSL:1	c.928A>G	p.Thr310Ala	missense	Exon 11 of 17	ENSP00000416687.3
	MLH1	ENST00000413740.2	TSL:1	c.928A>G	p.Thr310Ala	missense	Exon 11 of 15	ENSP00000416476.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.0000239 AC: 6 AN: 251418 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000173

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000684 AC: 10 AN: 1461890 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 727248

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.000201 AC: 9 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1112010

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000370 Hom.: 0

Bravo AF: 0.00000378

ExAC AF: 0.0000247 AC: 3

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:9 Benign:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Colorectal cancer, hereditary nonpolyposis, type 2 Uncertain:2 Benign:1

Mar 28, 2024

Baylor Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Nov 14, 2023

Myriad Genetics, Inc.

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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: 27363726].

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease.

not provided Uncertain:2

Jul 29, 2024

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The MLH1 c.928A>G (p.Thr310Ala) variant has been reported in the published literature in an individual with colorectal cancer (PMID: 32973888 (2020)). The frequency of this variant in the general population, 0.00017 (6/34590 chromosomes (Genome Aggregation Database, http://gnomad.broadinstitute.org)), is uninformative in the assessment of its pathogenicity. Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded predictions that this variant is damaging. Based on the available information, we are unable to determine the clinical significance of this variant.

May 15, 2017

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is denoted MLH1 c.928A>G at the cDNA level, p.Thr310Ala (T310A) at the protein level, and results in the change of a Threonine to an Alanine (ACA>GCA). This variant has not, to our knowledge, been published in the literature as pathogenic or benign. MLH1 Thr310Ala was observed at an allele frequency of 0.02% (3/11578) in individuals of Latino ancestry in large population cohorts (NHLBI Exome Sequencing Project, The 1000 Genomes Consortium 2015, Lek 2016). Since Threonine and Alanine differ in polarity, charge, size or other properties, this is considered a non-conservative amino acid substitution. MLH1 Thr310Ala occurs at a position that is conserved across species and is located within the N-terminal ATPase domain (Andersen 2012). In silico analyses predict that this variant is probably damaging to protein structure and function. Based on currently available evidence, it is unclear whether MLH1 Thr310Ala is a pathogenic or benign variant. We consider it to be a variant of uncertain significance.

Hereditary cancer-predisposing syndrome Uncertain:2

May 08, 2024

Color Diagnostics, LLC DBA Color Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces threonine with alanine at codon 310 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 been reported in an individual affected with early onset and mismatch repair deficient colorectal cancer (PMID: 32973888). This variant has been identified in 6/251418 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.

Mar 21, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.T310A variant (also known as c.928A>G), located in coding exon 11 of the MLH1 gene, results from an A to G substitution at nucleotide position 928. The threonine at codon 310 is replaced by alanine, an amino acid with similar properties. This variant was identified in a 32 year old male with MMR-deficient colorectal cancer, but specific results from IHC analysis were not provided by the authors (Xu Y et al. Front Genet, 2020 Aug;11:991). 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

Jan 15, 2024

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

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: MLH1 c.928A>G (p.Thr310Ala) results in a non-conservative amino acid change located in the DNA mismatch repair protein, S5 domain 2-like domain (IPR013507) of the encoded protein sequence. Five 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 251418 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.928A>G has been reported in the literature in at least one individual affected with colorectal cancer and MMR deficiency (e.g., Xu_2020). These data do not allow any conclusion about variant significance. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication have been ascertained in the context of this evaluation (PMID: 32973888). ClinVar contains an entry for this variant (Variation ID: 237351). Based on the evidence outlined above, the variant was classified as uncertain significance.

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

Apr 12, 2024

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Lynch syndrome Uncertain:1

Aug 23, 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 threonine with alanine at codon 310 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 been reported in an individual affected with early onset and mismatch repair deficient colorectal cancer (PMID: 32973888). This variant has been identified in 6/251418 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 Benign:1

Jan 19, 2025

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	Pathogenic	0.83
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Pathogenic	0.37
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.76	D
Eigen	Pathogenic	0.81
Eigen_PC	Pathogenic	0.77
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Uncertain	0.26	D
MetaRNN	Pathogenic	0.87	D
MetaSVM	Uncertain	0.43	D
MutationAssessor	Uncertain	2.5	M
PhyloP100		8.9
PrimateAI	Uncertain	0.73	T
PROVEAN	Pathogenic	-4.9	D
REVEL	Pathogenic	0.86
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.79
MutPred		0.66		Loss of glycosylation at T310 (P = 0.0147)
MVP		0.96
MPC		0.40
ClinPred		0.93	D
GERP RS		5.8
PromoterAI		0.0040	Neutral
Varity_R		0.90
gMVP		0.60
Mutation Taster		=22/78	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs779581111; hg19: chr3-37061844;