rs1060500710

chr3-37007010-A-G

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The NM_000249.4(MLH1):c.400A>G(p.Lys134Glu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,652 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. K134I) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: 9.02

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 5 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, 15 uncertain in NM_000249.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.806

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MLH1	NM_000249.4	c.400A>G	p.Lys134Glu	missense_variant	5/19	ENST00000231790.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MLH1	ENST00000231790.8	c.400A>G	p.Lys134Glu	missense_variant	5/19	1	NM_000249.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251420 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135896

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: 0.00

Gnomad OTH exome AF: 0.000163

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461652 Hom.: 0 Cov.: 30 AF XY: 0.00000275 AC XY: 2 AN XY: 727132

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: 8.99e-7

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000450 Hom.: 0

Bravo AF: 0.00000756

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Institute for Clinical Genetics, University Hospital TU Dresden, University Hospital TU Dresden	Nov 03, 2021	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Jun 29, 2023	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; Published functional studies demonstrate mismatch repair activity close to wild type (Plotz et al., 2006); Not observed in any cases, but was observed in unaffected controls from a breast cancer study (Dorling et al., 2021); This variant is associated with the following publications: (PMID: 24362816, 22753075, 36909643, 17135187, 33471991) -

Lynch syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

All of Us Research Program, National Institutes of Health

Dec 01, 2023

- -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Nov 03, 2023

This sequence change replaces lysine, which is basic and polar, with glutamic acid, which is acidic and polar, at codon 134 of the MLH1 protein (p.Lys134Glu). This variant is present in population databases (no rsID available, 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: 405430). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt MLH1 protein function with a negative predictive value of 95%. Experimental studies have shown that this missense change does not substantially affect MLH1 function (PMID: 17135187). 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. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 26, 2021

The p.K134E variant (also known as c.400A>G), located in coding exon 5 of the MLH1 gene, results from an A to G substitution at nucleotide position 400. The lysine at codon 134 is replaced by glutamic acid, an amino acid with similar properties. In one study, an in vitro mismatch repair assay concluded this alteration does not significantly impair the mismatch repair ability of MutLα, the MLH1-PMS2 heterodimer (Plotz G et al. Nucleic Acids Res., 2006 Nov;34:6574-86). In another study, this variant was reported in 0/60,466 breast cancer cases and in 1/53,461 controls (Dorling et al. N Engl J Med. 2021 02;384:428-439). This amino acid position is highly 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Pathogenic	0.33	D
BayesDel_noAF	Pathogenic	0.23
Cadd	Pathogenic	28
Dann	Uncertain	1.0
DEOGEN2	Uncertain	0.71	D;.;T
Eigen	Pathogenic	0.74
Eigen_PC	Pathogenic	0.78
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.89	D;D;D
M_CAP	Benign	0.065	D
MetaRNN	Pathogenic	0.81	D;D;D
MetaSVM	Uncertain	-0.014	T
MutationAssessor	Benign	1.3	L;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D
PrimateAI	Uncertain	0.73	T
PROVEAN	Uncertain	-3.3	D;D;D
REVEL	Uncertain	0.63
Sift	Uncertain	0.0020	D;D;T
Sift4G	Uncertain	0.0040	D;D;T
Polyphen		0.89	P;.;.
Vest4		0.67
MVP		0.95
MPC		0.46
ClinPred		0.83	D
GERP RS		6.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.54
gMVP		0.84

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: rs1060500710; hg19: chr3-37048501;