chr3-37048952-T-G

Variant names:

• chr3-37048952-T-G
• rs63750809
• NM_000249.4:c.2038T>G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM5 PP3

The NM_000249.4(MLH1):​c.2038T>G​(p.Cys680Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000349 in 1,461,838 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. C680R) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000035 (0 hom.)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:11 B:2
• Conservation: PhyloP100: 3.08

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM5: Other missense variant is known to change same aminoacid residue: Variant chr3-37048952-T-C is described in Lovd as [Likely_pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.783

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4	c.2038T>G	p.Cys680Gly	missense_variant	Exon 18 of 19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.2038T>G	p.Cys680Gly	missense_variant	Exon 18 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000716 AC: 18 AN: 251246 Hom.: 0 AF XY: 0.0000957 AC XY: 13 AN XY: 135780

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.000523

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000326

GnomAD4 exome AF: 0.0000349 AC: 51 AN: 1461838 Hom.: 0 Cov.: 31 AF XY: 0.0000495 AC XY: 36 AN XY: 727232

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: 0.000568

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome Cov.: 32

ExAC AF: 0.0000988 AC: 12

Asia WGS AF: 0.00115 AC: 4 AN: 3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:11 Benign:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Colorectal cancer, hereditary nonpolyposis, type 2 Pathogenic:1 Uncertain:5

Dec 07, 2019

Foundation for Research in Genetics and Endocrinology, FRIGE's Institute of Human Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

A Heterozygous missense variation in exon 18 of the MLH1 gene that results in the amino acid substitution of Glycine for Cysteine at codon 680 was detected. The observed variant c.2038T>G (p.Cys680Gly) has previously been reported in the patient affected with colorectal cancer and it is documented as likely pathogenic in InSiGHT and ClinVar database. The p.Cys680Gly variant has not been reported in the 1000 Genomes and has a minor allele frequency of 0.01% in the ExAC databases. The in silico predictions of the variant are damaging by SIFT, LRT and MutationTaster2 tools. The reference codon is conserved across mammals. In summary, the variant meets our criteria to be classified as likely pathogenic. -

Apr 27, 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. -

Mar 15, 2023

Myriad Genetics, Inc.

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is classified as a variant of uncertain significance as there is insufficient evidence to determine its impact on protein function and/or cancer risk. -

Jan 02, 2024

Baylor Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Feb 14, 2023

Neuberg Centre For Genomic Medicine, NCGM

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The missense c.2038T>G(p.Cys680Gly) variant in MLH1 gene has been reported in heterozygous state in individuals affected with MLH1 related disorders (Rajkumar T, et. al., 2004; Dominguez-Valentin M, et. al., 2014; Mittal A, et. al., 2022). The variant is reported with an allele frequency of 0.007% in the gnomAD exomes database and is novel (not in any individuals) in 1000 Genomes database. This variant has been reported to the ClinVar database as Likely Benign/Likely Pathogenic/Uncertain Significance (multiple submissions). The amino acid change p.Cys680Gly in MLH1 is predicted as conserved by GERP++ and PhyloP across 100 vertebrates. The amino acid Cys at position 680 is changed to a Gly changing protein sequence and it might alter its composition and physico-chemical properties. For these reasons, this variant has been classified as Variant of Uncertain Significance (VUS). -

Jul 12, 2016

Counsyl

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Hereditary cancer-predisposing syndrome Uncertain:2 Benign:1

Mar 24, 2021

Ambry Genetics

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This alteration is classified as likely 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. -

Feb 28, 2024

Color Diagnostics, LLC DBA Color Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces cysteine with glycine at codon 680 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 three Lynch syndrome-associated cancers (PMID: 15345113). In a large breast cancer case-control study, this variant was not reported in affected cases and reported in four healthy controls (PMID: 33471991). This variant has been identified in 18/251246 chromosomes in the general population by the Genome Aggregation Database (gnomAD). A different missense mutation at the same codon, p.Cys680Arg, has been reported in multiple individuals and families affected with Lynch syndrome (PMID: 18931482, 23729658, 25077178, 27601186) and shown in a functional study to be defective in DNA mismatch repair in vitro (PMID: 25077178). 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. -

Dec 23, 2021

Sema4, Sema4

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: curation

- -

Lynch syndrome Uncertain:2

Dec 08, 2022

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jun 11, 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 cysteine with glycine at codon 680 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 three Lynch syndrome-associated cancers (PMID: 15345113). In a large breast cancer case-control study, this variant was not reported in affected cases and reported in four healthy controls (PMID: 33471991). This variant has been identified in 18/251246 chromosomes in the general population by the Genome Aggregation Database (gnomAD). A different missense mutation at the same codon, p.Cys680Arg, has been reported in multiple individuals and families affected with Lynch syndrome (PMID: 18931482, 23729658, 25077178, 27601186) and shown in a functional study to be defective in DNA mismatch repair in vitro (PMID: 25077178). 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 specified Uncertain:1

Apr 15, 2022

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.2038T>G (p.Cys680Gly) results in a non-conservative amino acid change located in the DNA mismatch repair protein Mlh1, C-terminal domain (IPR032189) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 7.2e-05 in 251246 control chromosomes. This frequency is not significantly higher than expected for a pathogenic variant in MLH1 causing Lynch Syndrome (7.2e-05 vs 0.00071), allowing no conclusion about variant significance. c.2038T>G has been reported in the literature as a variant of probable significance in one individual with MSI-high colorectal tumor, a personal and family history of HNPCC-related cancers who was reportedly genotyped only for MLH1 and MSH2 genes (example Rajkumar_2004, cited in Bhai_2020). These report(s) do not provide unequivocal conclusions about association of the variant with Lynch Syndrome. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Six clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation (Likely pathogenic, n=1; VUS, n=5). Based on the evidence outlined above, the variant was classified as uncertain significance. -

not provided Uncertain:1

Dec 28, 2023

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 18383312, 15345113, 36200007, 12799449, 20533529, 22753075) -

Hereditary nonpolyposis colorectal neoplasms Benign:1

Jan 14, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.36
BayesDel_addAF	Uncertain	0.051	T
BayesDel_noAF	Pathogenic	0.18
CADD	Pathogenic	26
DANN	Uncertain	0.98
DEOGEN2	Pathogenic	0.86	D;.;.;.;.;.
Eigen	Uncertain	0.38
Eigen_PC	Uncertain	0.41
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Benign	0.66	T;T;.;.;.;T
M_CAP	Uncertain	0.27	D
MetaRNN	Pathogenic	0.78	D;D;D;D;D;D
MetaSVM	Uncertain	0.61	D
MutationAssessor	Uncertain	2.5	M;.;.;.;.;.
PrimateAI	Uncertain	0.62	T
PROVEAN	Pathogenic	-6.1	D;D;D;D;D;D
REVEL	Pathogenic	0.79
Sift	Uncertain	0.0040	D;D;D;D;D;D
Sift4G	Uncertain	0.021	D;D;D;D;D;D
Polyphen		0.47	P;.;.;.;.;.
Vest4		0.83
MutPred		0.70		Gain of disorder (P = 0.0202);.;.;.;.;.;
MVP		0.90
MPC		0.18
ClinPred		0.35	T
GERP RS		4.8
Varity_R		0.96
gMVP		0.81

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

Other links and lift over

dbSNP: rs63750809; hg19: chr3-37090443;