NM_000249.4:c.1730C>G

Variant names:

• chr3-37042330-C-G
• rs56185292
• NM_000249.4:c.1730C>G

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_000249.4(MLH1):​c.1730C>G​(p.Ser577Trp) variant causes a missense, splice region change. The variant was absent in control chromosomes in GnomAD project. 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 Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. S577S) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MLH1 NM_000249.4 missense, splice_region
• Scores: Splicing: ADA: 0.9911
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.06

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 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.885

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4	c.1730C>G	p.Ser577Trp	missense_variant, splice_region_variant	Exon 15 of 19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.1730C>G	p.Ser577Trp	missense_variant, splice_region_variant	Exon 15 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Apr 28, 2014

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is denoted MLH1 c.1730C>G at the cDNA level, p.Ser577Trp (S577W) at the protein level, and results in the change of a Serine to a Tryptophan (TCG>TGG). This variant has not, to our knowledge, been published in the literature as pathogenic or benign. MLH1 Ser577Trp was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. Since Serine and Tryptophan differ in polarity, charge, size or other properties, this is considered a non-conservative amino acid substitution. MLH1 Ser577Trp occurs at a position that is highly conserved across species and is located in the region of interaction with PMS2/MLH3/PMS1 (Raevaara 2005). In silico analyses predict that this variant is probably damaging to protein structure and function. Based on currently available information, it is unclear whether MLH1 Ser577Trp is pathogenic or benign. We consider it to be a variant of uncertain significance. -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Mar 12, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces serine, which is neutral and polar, with tryptophan, which is neutral and slightly polar, at codon 577 of the MLH1 protein (p.Ser577Trp). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with MLH1-related conditions. ClinVar contains an entry for this variant (Variation ID: 182528). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.72
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.47
CADD	Pathogenic	33
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.93	D;.;.;.;.;.
Eigen	Pathogenic	0.90
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.89	D;D;.;.;.;D
M_CAP	Pathogenic	0.42	D
MetaRNN	Pathogenic	0.89	D;D;D;D;D;D
MetaSVM	Pathogenic	0.93	D
MutationAssessor	Pathogenic	3.3	M;.;.;.;.;.
PrimateAI	Uncertain	0.70	T
PROVEAN	Pathogenic	-5.4	D;D;D;D;D;D
REVEL	Pathogenic	0.87
Sift	Uncertain	0.0010	D;D;D;D;D;D
Sift4G	Uncertain	0.0020	D;D;D;D;D;D
Polyphen		0.99	D;.;.;.;.;.
Vest4		0.78
MutPred		0.49		Loss of phosphorylation at S577 (P = 0.0514);.;.;.;.;.;
MVP		0.97
MPC		0.45
ClinPred		1.0	D
GERP RS		5.4
Varity_R		0.95
gMVP		0.83

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.99
dbscSNV1_RF	Pathogenic	0.85
SpliceAI score (max)		0.24		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.24		Position offset: 1

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

Publications

LitVar

Other links and lift over

dbSNP: rs56185292; hg19: chr3-37083821;