rs121912958

chr3-37012098-C-Tchr3-37012098-C-A

Variant summary

Our verdict is Pathogenic. Variant got 19 ACMG points: 19P and 0B. PVS1 PM2 PP3 PP5_Very_Strong

The NM_000249.4(MLH1):c.676C>T(p.Arg226Ter) variant causes a stop gained, splice region change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000688 in 1,452,898 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★★). Synonymous variant affecting the same amino acid position (i.e. R226R) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: MLH1 NM_000249.4 stop_gained, splice_region
• Scores: Splicing: ADA: 0.9979
• Clinical Significance: Pathogenic reviewed by expert panel P:23 U:1
• Conservation: PhyloP100: 1.21

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 Pathogenic. Variant got 19 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.
• PP5: Variant 3-37012098-C-T is Pathogenic according to our data. Variant chr3-37012098-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 17087.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr3-37012098-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MLH1	NM_000249.4	c.676C>T	p.Arg226Ter	stop_gained, splice_region_variant	8/19	ENST00000231790.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MLH1	ENST00000231790.8	c.676C>T	p.Arg226Ter	stop_gained, splice_region_variant	8/19	1	NM_000249.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 250982 Hom.: 0 AF XY: 0.00000737 AC XY: 1 AN XY: 135634

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: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000882

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.88e-7 AC: 1 AN: 1452898 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 723392

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.06e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:23 Uncertain:1

Revision: reviewed by expert panel

Submissions by phenotype

not provided Pathogenic:6 Uncertain:1

Pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen	-	- -
Uncertain significance, no assertion criteria provided	clinical testing	Department of Pathology and Laboratory Medicine, Sinai Health System	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	May 12, 2021	This variant causes the premature termination of MLH1 protein synthesis. In the published literature, this variant has been reported in individuals and families with Lynch syndrome (PMIDs: 32635641 (2020), 28944238 (2017), 28874130 (2017), 21247423 (2011), 23047549 (2012)), and constitutional mismatch repair deficiency (CMMRD) syndrome (PMID: 17889038 (2008)). The frequency of this variant in the general population, 0.000004 (1/250982 chromosomes (Genome Aggregation Database, http://gnomad.broadinstitute.org)), is consistent with pathogenicity. Analysis of this variant using software algorithms for the prediction of the effect of nucleotide changes on splicing yielded predictions that this variant does not affect MLH1 mRNA splicing . Based on the available information, this variant is classified as pathogenic. -
Pathogenic, no assertion criteria provided	research	Mayo Clinic Laboratories, Mayo Clinic	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Apr 11, 2022	- -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Aug 22, 2019	Nonsense variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; Not observed at a significant frequency in large population cohorts (Lek 2016); Truncating variants in this gene are considered pathogenic by a well-established clinical consortium and/or database; This variant is associated with the following publications: (PMID: 27601186, 25980754, 28514183, 10874307, 21056691, 21868491, 21247423, 20924129, 20045164, 19690142, 18307539, 15655560, 9927033, 8872463, 23047549, 25525159, 17889038, 22949379, 15849733, 12624141, 21879275, 22776989, 9472100, 24344984, 24456667, 28445943, 26681312, 28449805, 28944238, 11343035, 28502729, 29478780, 28874130, 30521064, 30720243, 30262796, 29505604, 30998989, 29625052, 30217226, 32719484) -

Colorectal cancer, hereditary nonpolyposis, type 2 Pathogenic:6

Pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Mar 16, 2023	This variant is considered pathogenic. This variant creates a termination codon and is predicted to result in premature protein truncation. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Jul 14, 2021	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	May 01, 2001	- -
Pathogenic, criteria provided, single submitter	clinical testing	Genetics and Molecular Pathology, SA Pathology	Nov 22, 2021	- -
Pathogenic, criteria provided, single submitter	clinical testing	MGZ Medical Genetics Center	Feb 02, 2022	- -
Pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Jul 19, 2017	- -

Lynch syndrome Pathogenic:3

Pathogenic, reviewed by expert panel	research	International Society for Gastrointestinal Hereditary Tumours (InSiGHT)	Sep 05, 2013	Coding sequence variation resulting in a stop codon -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 14, 2018	Variant summary: MLH1 c.676C>T (p.Arg226X) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Though the variant is located close to a canonical splice site, 5/5 computational tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 4.1e-06 in 245718 control chromosomes (gnomAD). The variant, c.676C>T, has been reported in the literature as a pathogenic variant in multiple individuals affected with Lynch Syndrome (e.g. Moslein 1996, Lagerstedt-Robinson 2016, Rossi 2017, Sunga 2017. These data indicate that the variant is very likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Six ClinVar submissions from other clinical diagnostic laboratories (evaluation after 2014) cites the variant as "pathogenic." Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	All of Us Research Program, National Institutes of Health	Oct 02, 2023	This variant causes a C to T nucleotide change in exon 8 of the MLH1 gene, creating a premature translation stop signal. This variant is expected to result in an absent or non-functional protein product. To our knowledge, functional studies have not been performed for this variant. This variant has been reported in multiple individuals and families affected with Lynch syndrome-associated cancer, many of whom met the Amsterdam II criteria (PMID: 9927033, 15655560, 15849733, 18307539, 19690142, 20045164, 20924129, 21247423, 24344984, 24362816, 27601186, 28514183, 28874130). This variant has also been reported in homozygous carriers affected with constitutional mismatch repair deficiency syndrome (PMID: 17889038), and has been shown to segregate with disease in families (PMID: 15655560, 21247423, 24362816). This variant has also been identified in an individual affected with ovarian cancer (PMID: 23047549). This variant has been identified in 1/250982 chromosomes in the general population by the Genome Aggregation Database (gnomAD). Loss of MLH1 function is a known mechanism of disease. Based on the available evidence, this variant is classified as Pathogenic. -

Hereditary cancer-predisposing syndrome Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Ambry Genetics	Aug 11, 2021	The p.R226* pathogenic mutation (also known as c.676C>T), located in coding exon 8 of the MLH1 gene, results from a C to T substitution at nucleotide position 676. This changes the amino acid from an arginine to a stop codon within coding exon 8. This mutation has been detected in multiple families meeting Amsterdam Criteria for a clinical diagnosis of Hereditary Non-Polyposis Colorectal Cancer (HNPCC)/Lynch syndrome), several with tumors demonstrating microsatellite instability and loss of MLH1 protein on immunohistochemistry (Moslein G et al. Hum Mol Genet, 1996 Sep;5:1245-52; Marcos I et al. J Pediatr, 2006 Jun;148:837-9; Mueller J et al. Cancer Res, 2009 Sep;69:7053-61; Coolbaugh-Murphy MI et al. Hum Mutat, 2010 Mar;31:317-24; Chang SC et al. Surgery, 2010 May;147:720-8; Jasperson KW et al. Fam Cancer, 2010 Jun;9:99-107; Giráldez MD et al. Clin Cancer Res, 2010 Nov;16:5402-13; Limburg PJ et al. Clin Gastroenterol Hepatol, 2011 Jun;9:497-502; Castillejo A et al. BMC Med. Genet., 2011;12:12; Pal T et al. Br J Cancer, 2012 Nov;107:1783-90; Pérez-Carbonell L et al. Gut, 2012 Jun;61:865-72; Hinrichsen I et al. Mol Cancer, 2014 Jan;13:11; Dominguez-Valentin M et al. Front Oncol, 2016 Aug;6:189; Lagerstedt-Robinson K et al. Oncol Rep, 2016 Nov;36:2823-2835; Zhang J et al. Oncotarget, 2017 Apr;8:24533-24547; Espenschied CR et al. J Clin Oncol, 2017 Aug;35:2568-2575; Sunga AY et al. Cancer Genet, 2017 04;212-213:1-7; Rossi BM et al. BMC Cancer, 2017 Sep;17:623; DeRycke MS et al. Mol Genet Genomic Med, 2017 Sep;5:553-569; Gong R et al. Cancer Manag Res, 2019 Apr;11:3721-3739; Jiang W et al. Int J Cancer, 2019 05;144:2161-2168; Dámaso E et al. Cancers (Basel), 2020 Jul;12:). This mutation has been reported as homozygous in individuals with features of constitutional mismatch repair deficiency (CMMRD) syndrome (Ricciardone MD et al. Cancer Res, 1999 Jan;59:290-3; Apessos A et al. Br J Cancer, 2005 Jan;92:396-404). This mutation has also been reported in 1/327 Mexican patients with a personal and/or family history suspicious for hereditary breast and ovarian cancer syndrome (Quezada Urban R et al. Cancers (Basel), 2018 Sep;10:). In addition to the clinical data presented in the literature, this alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. As such, this alteration is interpreted as a disease-causing mutation. -
Pathogenic, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Apr 11, 2023	This variant causes a C to T nucleotide change in exon 8 of the MLH1 gene, creating a premature translation stop signal. This variant is expected to result in an absent or non-functional protein product. To our knowledge, functional studies have not been performed for this variant. This variant has been reported in multiple individuals and families affected with Lynch syndrome-associated cancer, many of whom met the Amsterdam II criteria (PMID: 9927033, 15655560, 15849733, 18307539, 19690142, 20045164, 20924129, 21247423, 24344984, 24362816, 27601186, 28514183, 28874130). This variant has also been reported in homozygous carriers affected with constitutional mismatch repair deficiency syndrome (PMID: 17889038), and has been shown to segregate with disease in families (PMID: 15655560, 21247423, 24362816). This variant has also been identified in an individual affected with ovarian cancer (PMID: 23047549). This variant has been identified in 1/250982 chromosomes in the general population by the Genome Aggregation Database (gnomAD). Loss of MLH1 function is a known mechanism of disease. Based on the available evidence, this variant is classified as Pathogenic. -

Breast and/or ovarian cancer Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

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

Sep 15, 2021

- -

Lynch syndrome 1 Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Ding PR Lab, Sun Yat-sen University Cancer Center

-

- -

Lynch-like syndrome Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Constitutional Genetics Lab, Leon Berard Cancer Center

Jul 01, 2019

- -

Muir-Torré syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Laboratorio de Genetica e Diagnostico Molecular, Hospital Israelita Albert Einstein

Jun 21, 2022

ACMG classification criteria: PVS1 very strong, PS4 strong, PM2 moderated -

Hereditary nonpolyposis colorectal neoplasms Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Jan 31, 2024

This sequence change creates a premature translational stop signal (p.Arg226*) in the MLH1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in MLH1 are known to be pathogenic (PMID: 15713769, 24362816). This variant is present in population databases (rs63751615, gnomAD 0.0009%). This premature translational stop signal has been observed in individual(s) with ovarian cancer and Lynch syndrome (PMID: 8872463, 10874307, 15655560, 15849733, 17889038, 21247423, 23047549, 24344984). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 17087). For these reasons, this variant has been classified as Pathogenic. -

Mismatch repair cancer syndrome 1 Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

May 01, 2001

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.62
Cadd	Pathogenic	41
Dann	Uncertain	1.0
Eigen	Pathogenic	0.78
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Uncertain	0.96	D
MutationTaster	Benign	1.0	A;A;A;A;A;A
Vest4		0.89
GERP RS		4.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.89
SpliceAI score (max)		0.090		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: rs63751615; hg19: chr3-37053589; COSMIC: COSV51614124; COSMIC: COSV51614124;