3-37048938-G-T

Variant names:

• chr3-37048938-G-T
• rs781637991
• NM_000249.4:c.2024G>T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_000249.4(MLH1):​c.2024G>T​(p.Ser675Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,828 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 Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 2.88

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.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.805

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4	c.2024G>T	p.Ser675Ile	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.2024G>T	p.Ser675Ile	missense_variant	Exon 18 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461828 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727216

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: 0.00000360

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:2

Jul 23, 2021

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.S675I variant (also known as c.2024G>T), located in coding exon 18 of the MLH1 gene, results from a G to T substitution at nucleotide position 2024. The serine at codon 675 is replaced by isoleucine, an amino acid with dissimilar properties. This amino acid position is well conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Apr 18, 2018

True Health Diagnostics

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

not provided Uncertain:1

Aug 11, 2024

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; Has not been previously published as pathogenic or benign to our knowledge; This variant is associated with the following publications: (PMID: 12799449, 20533529, 22753075) -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Jan 24, 2025

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 isoleucine, which is neutral and non-polar, at codon 675 of the MLH1 protein (p.Ser675Ile). 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: 237328). Invitae Evidence Modeling incorporating data from in vitro experimental studies (internal data) indicates that this missense variant is not expected to disrupt MLH1 function with a negative predictive value of 95%. 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	Uncertain	0.50
BayesDel_addAF	Pathogenic	0.33	D
BayesDel_noAF	Pathogenic	0.23
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.93	D;.;.;.;.;.
Eigen	Pathogenic	0.69
Eigen_PC	Pathogenic	0.70
FATHMM_MKL	Uncertain	0.91	D
LIST_S2	Uncertain	0.92	D;D;.;.;.;D
M_CAP	Pathogenic	0.31	D
MetaRNN	Pathogenic	0.81	D;D;D;D;D;D
MetaSVM	Pathogenic	0.86	D
MutationAssessor	Pathogenic	3.0	M;.;.;.;.;.
PrimateAI	Uncertain	0.57	T
PROVEAN	Uncertain	-3.5	D;D;D;D;D;D
REVEL	Pathogenic	0.72
Sift	Uncertain	0.0060	D;D;D;D;D;D
Sift4G	Uncertain	0.049	D;T;T;T;T;D
Polyphen		0.98	D;.;.;.;.;.
Vest4		0.60
MutPred		0.43		Loss of disorder (P = 0.0099);.;.;.;.;.;
MVP		0.91
MPC		0.22
ClinPred		0.96	D
GERP RS		5.9
Varity_R		0.86
gMVP		0.73

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs781637991; hg19: chr3-37090429;