3-37050621-C-T

Variant names:

• chr3-37050621-C-T
• rs587779958
• NM_000249.4:c.2239C>T

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM1 PM2

The NM_000249.4(MLH1):​c.2239C>T​(p.Pro747Ser) variant causes a missense change. The variant allele was found at a frequency of 0.00000274 in 1,461,836 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. P747R) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7 B:2
• Conservation: PhyloP100: 5.80
• Publications: 8 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 7 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 39 uncertain in NM_000249.4
• PM2: Very rare variant in population databases, with high coverage

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.2239C>T	p.Pro747Ser	missense	Exon 19 of 19	NP_000240.1
	MLH1	NM_001354628.2		c.2146C>T	p.Pro716Ser	missense	Exon 18 of 18	NP_001341557.1
	MLH1	NM_001354629.2		c.2140C>T	p.Pro714Ser	missense	Exon 18 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.2239C>T	p.Pro747Ser	missense	Exon 19 of 19	ENSP00000231790.3
	MLH1	ENST00000456676.7	TSL:1	c.2032C>T	p.Pro678Ser	missense	Exon 17 of 17	ENSP00000416687.3
	MLH1	ENST00000458205.6	TSL:1	c.1516C>T	p.Pro506Ser	missense	Exon 20 of 20	ENSP00000402667.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251292 AF XY: 0.00000736

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461836 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 727226

African (AFR) AF: 0.0000299 AC: 1 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 39694

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53412

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

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1111968

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

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000533 Hom.: 0

Bravo AF: 0.0000113

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:7 Benign:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

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

Mar 19, 2024

Baylor Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

May 10, 2024

Molecular Pathology, Peter Maccallum Cancer Centre

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Dec 02, 2024

Myriad Genetics, Inc.

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered 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]. Homozygosity for this variant has been confirmed in one or more individuals lacking clinical features consistent with gene-specific recessive disease, indicating that this variant is unlikely to be pathogenic.

Hereditary cancer-predisposing syndrome Uncertain:2

May 26, 2023

Color Diagnostics, LLC DBA Color Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces proline with serine at codon 747 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 colorectal cancer (PMID: 31360874). This variant has been identified in 1/251292 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 10, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.P747S variant (also known as c.2239C>T), located in coding exon 19 of the MLH1 gene, results from a C to T substitution at nucleotide position 2239. The proline at codon 747 is replaced by serine, an amino acid with similar properties. This variant was identified in an individual diagnosed with colorectal cancer (Toh MR et al. JNCI Cancer Spectr, 2018 Oct;2:pky054). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear.

not specified Uncertain:1

Nov 07, 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.2239C>T (p.Pro747Ser) results in a non-conservative amino acid change located in the DNA mismatch repair protein Mlh1 C-terminus (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 4e-06 in 251292 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.2239C>T has been reported in the literature in individuals with breast or colorectal cancer undergoing multigene panel testing (e.g. Yorczyk_2015, Toh_2018, Pearlman_2021) These report(s) do not provide unequivocal conclusions about association of the variant with Hereditary Nonpolyposis Colorectal Cancer. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 34250417, 31360874, 25318351). ClinVar contains an entry for this variant (Variation ID: 127622). 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

May 29, 2024

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

not provided Uncertain:1

Oct 05, 2023

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); 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: 12799449, 20533529, 22753075, 31360874, 25318351)

Hereditary nonpolyposis colorectal neoplasms Benign:1

Jan 23, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.32
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Pathogenic	0.22
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.82	D
Eigen	Pathogenic	0.77
Eigen_PC	Pathogenic	0.75
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.96	D
M_CAP	Pathogenic	0.31	D
MetaRNN	Uncertain	0.67	D
MetaSVM	Pathogenic	0.97	D
MutationAssessor	Uncertain	2.7	M
PhyloP100		5.8
PrimateAI	Uncertain	0.69	T
PROVEAN	Pathogenic	-4.7	D
REVEL	Pathogenic	0.85
Sift	Uncertain	0.0030	D
Sift4G	Benign	0.081	T
Polyphen		0.99	D
Vest4		0.53
MutPred		0.74		Loss of ubiquitination at K751 (P = 0.0992)
MVP		0.86
MPC		0.16
ClinPred		0.99	D
GERP RS		5.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.76
gMVP		0.66
Mutation Taster		=27/73	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: rs587779958; hg19: chr3-37092112; COSMIC: COSV99212452; COSMIC: COSV99212452;