chr3-37001050-T-G

Variant names:

• chr3-37001050-T-G
• rs4647220
• NM_000249.4:c.303T>G

Variant summary

Our verdict is Benign. The variant received -19 ACMG points: 0P and 19B. BP4_Moderate BP6_Very_Strong BP7 BS1 BS2

The NM_000249.4(MLH1):​c.303T>G​(p.Gly101Gly) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00109 in 1,585,538 control chromosomes in the GnomAD database, including 29 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★★).

• Frequency:
  • Genomes: 𝑓 0.00074 (4 hom., cov: 32)
  • Exomes 𝑓: 0.0011 (25 hom.)
• Consequence: MLH1 NM_000249.4 synonymous
• Clinical Significance: Likely benign reviewed by expert panel B:19 O:1
• Conservation: PhyloP100: -0.441
• Publications: 11 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: Benign. The variant received -19 ACMG points.

• BP4: Computational evidence support a benign effect (REVEL=0.035).
• BP6: Variant 3-37001050-T-G is Benign according to our data. Variant chr3-37001050-T-G is described in ClinVar as Likely_benign. ClinVar VariationId is 90140.Status of the report is reviewed_by_expert_panel, 3 stars.
• BP7: Synonymous conserved (PhyloP=-0.441 with no splicing effect.
• BS1: Variant frequency is greater than expected in population sas. GnomAd4 allele frequency = 0.000742 (113/152280) while in subpopulation SAS AF = 0.0226 (109/4824). AF 95% confidence interval is 0.0192. There are 4 homozygotes in GnomAd4. There are 79 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.
• BS2: High Homozygotes in GnomAd4 at 4 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4	c.303T>G	p.Gly101Gly	synonymous_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	c.303T>G	p.Gly101Gly	synonymous_variant	Exon 3 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes AF: 0.000736 AC: 112 AN: 152162 Hom.: 4 Cov.: 32

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000131

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.0224

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.00249 AC: 627 AN: 251344 AF XY: 0.00306

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.0000868

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00163

GnomAD4 exome AF: 0.00113 AC: 1621 AN: 1433258 Hom.: 25 Cov.: 26 AF XY: 0.00157 AC XY: 1122 AN XY: 714766

African (AFR) AF: 0.0000609 AC: 2 AN: 32840

American (AMR) AF: 0.0000448 AC: 2 AN: 44670

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25960

East Asian (EAS) AF: 0.0000507 AC: 2 AN: 39478

South Asian (SAS) AF: 0.0174 AC: 1491 AN: 85670

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53384

Middle Eastern (MID) AF: 0.00140 AC: 8 AN: 5712

European-Non Finnish (NFE) AF: 0.0000101 AC: 11 AN: 1086028

Other (OTH) AF: 0.00176 AC: 105 AN: 59516

GnomAD4 genome AF: 0.000742 AC: 113 AN: 152280 Hom.: 4 Cov.: 32 AF XY: 0.00106 AC XY: 79 AN XY: 74454

African (AFR) AF: 0.0000241 AC: 1 AN: 41572

American (AMR) AF: 0.000131 AC: 2 AN: 15304

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3466

East Asian (EAS) AF: 0.00 AC: 0 AN: 5182

South Asian (SAS) AF: 0.0226 AC: 109 AN: 4824

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10606

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68008

Other (OTH) AF: 0.00 AC: 0 AN: 2112

Alfa AF: 0.000237 Hom.: 0

Bravo AF: 0.0000982

ExAC AF: 0.00273 AC: 331

Asia WGS AF: 0.00925 AC: 32 AN: 3472

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Likely benign

Submissions summary: Benign:19 Other:1

Revision: reviewed by expert panel

Submissions by phenotype

not specified Benign:5 Other:1

Clinical Genetics, Academic Medical Center

Significance: Benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

Jun 15, 2016

Genetic Services Laboratory, University of Chicago

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Aug 15, 2014

GeneDx

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease.

Sep 19, 2013

ITMI

Significance: not provided

Review Status: no classification provided

Collection Method: reference population

Dec 06, 2021

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Mar 04, 2025

Center for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Colorectal cancer, hereditary nonpolyposis, type 2 Benign:3

Jul 07, 2023

KCCC/NGS Laboratory, Kuwait Cancer Control Center

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Feb 22, 2019

Illumina Laboratory Services, Illumina

Significance: Likely benign

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). Publications were found based on this search. The evidence from the literature, in combination with allele frequency data from public databases where available, was sufficient to determine this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign.

Nov 18, 2024

Myriad Genetics, Inc.

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered benign. This variant is a silent/synonymous amino acid change and it is not expected to impact splicing.

not provided Benign:3

May 20, 2016

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

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: The c.303T>G (p.Gly101=) in MLH1 gene is a synonymous change that involves a non-conserved nucleotide. 5/5 programs in Alamut predict that this variant does not affect normal splicing which was supported by a RNA-based functional assay by Thompson et al (2012). The variant is present in the control population dataset of ExAC at frequency of 0.0027 (331/121138) predominantly in individuals of South Asian descent (0.02; 329/16482 chrs) including 5 homozygous occurrences, suggesting that it is a polymorphism mainly found in South Asian population. The variant of interest been reported in affected individuals in whom either another known pathogenic variant was identified (Internal LCA data) or ICH results pointed out mutation(s) in other MMR genes (Mangold, 2007). In addition, the variant is cited as Benign/Likely Benign by reputable databases/clinical laboratories. Taking together, the variant is classified as Benign.

Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

Feb 04, 2022

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Hereditary cancer-predisposing syndrome Benign:3

Apr 23, 2015

Color Diagnostics, LLC DBA Color Health

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Sep 02, 2024

Molecular Diagnostics Laboratory, Catalan Institute of Oncology

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

BA1, BP4, BP7 c.303T>G located in exon 3 of the MLH1 gene, is predicted to result in no amino acid change, p.(Gly101=) (BP7). This variant is found in 610/30520 alleles, at a filtering allele frequency of 1.8% in the gnomAD v2.1.1 population database, South Asian non-cancer data set (BA1). The SpliceAI algorithm predicts no significant impact on splicing (BP4). A multifactorial likelihood analysis for the variant yielded a posterior probability of pathogenicity of 0.056 (PMID: 22949379). In addition, it has been reported in ClinVar database (6x as likely benign, 9x as benign) and in the LOVD database (17x as likely benign, 8x as benign, 2 uncertain significance) and classified as likely benign in the Insight database. Based on currently available information, the variant c.1002C>T is considered a benign variant according to ACMG guidelines.

Oct 23, 2019

Ambry Genetics

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This alteration is classified as benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity.

Lynch syndrome Benign:2

Sep 05, 2013

International Society for Gastrointestinal Hereditary Tumours (InSiGHT)

Significance: Likely benign

Review Status: reviewed by expert panel

Collection Method: research

Synonymous substitution with no effect on splicing & MAF 0.01-1%

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

The MLH1 p.Gly101Gly was identified in 1 of 20 proband chromosomes (frequency: 0.05) from individuals with Muir-Torre syndrome (Mangold 2007). The variant was also identified in dbSNP (ID: rs4647220) “With other allele”, in the 1000 Genomes Project in 32 of 5000 chromosomes (frequency: 0.0064) and in the Exome Aggregation Consortium (ExAC) database (released Jan 13, 2015) in 336 of 16482 chromosomes (frequency: 0.02) (or 329 individuals and 5 homozygous individuals) from a population of South Asian individuals, increasing the likelihood that this may be a low frequency benign variant in certain populations of origin. The variant was also identified in Clinvitae database (2x), “Mismatch Repair Genes Variant Database”, InSiGHT Colon Cancer Gene Variant Database (2X), the ClinVar database (classified as a likely benign by an expert panel), and UMD (1X as an unknown variant). The p.Gly101Gly variant is not expected to have clinical significance because it does not result in a change of amino acid and is not located in a known consensus splice site. The variant occurs outside of the splicing consensus sequence, 4th base from the 5' splice region, and 3 of 5 in silico or computational prediction software programs (SpliceSiteFinder, MaxEntScan, NNSPLICE, GeneSplicer, HumanSpliceFinder) predict a greater than 10% difference in splicing leading to the loss of a predicted splice site at a non-consensus splice site location; we cannot eliminate the possibility that an exon splice enhancer was modified and may lead to abnormal splicing or creation of a cryptic splice site however this information is not predictive enough to assume pathogenicity. Thompson et al. (2013) assessed MMR (mismatch repair) variants using multifactorial analysis, prior probabilities and likelihood ratios, as well as in vitro splicing assays and found the variant to be Class 3, uncertain significance, and having wildtype splicing. The identification of this variant in an individual with a co-occurring pathogenic variant (MSH2, c.1-?_366+?del) from our laboratory increases the likelihood this variant does not have clinical significance. In summary, based on the above information, this variant is classified as benign.

Breast and/or ovarian cancer Benign:1

Sep 14, 2021

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Muir-Torré syndrome Benign:1

Feb 01, 2025

KCCC/NGS Laboratory, Kuwait Cancer Control Center

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Hereditary nonpolyposis colorectal neoplasms Benign:1

Feb 02, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	-0.56	T
BayesDel_noAF	Benign	-0.56
CADD	Benign	13
DANN	Benign	0.72
DEOGEN2	Benign	0.0	.;.
Eigen	Benign	-0.35
Eigen_PC	Benign	-0.42
LIST_S2	Benign	0.0	.;.
MetaRNN	Benign	0.0	.;.
MutationAssessor	Benign	0.0	.;.
PhyloP100		-0.44
PROVEAN	Benign	0.0	.;.
Sift	Pathogenic	0.0	.;.
Sift4G	Pathogenic	0.0	.;.
Vest4		0.0
ClinPred		0.017	T
GERP RS		-6.8
Mutation Taster		=42/58	disease causing

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

Other links and lift over

dbSNP: rs4647220; hg19: chr3-37042541;