3-37011831-A-G

Position:

• chr3-37011831-A-G

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_000249.4(MLH1):​c.557A>G​(p.His186Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 8.27

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 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a helix (size 17) in uniprot entity MLH1_HUMAN there are 7 pathogenic changes around while only 1 benign (88%) in NM_000249.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.911

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MLH1	NM_000249.4	c.557A>G	p.His186Arg	missense_variant	7/19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.557A>G	p.His186Arg	missense_variant	7/19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	Nov 25, 2020	The p.H186R variant (also known as c.557A>G), located in coding exon 7 of the MLH1 gene, results from an A to G substitution at nucleotide position 557. The histidine at codon 186 is replaced by arginine, an amino acid with highly similar properties. 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Sep 13, 2019	This missense variant replaces histidine with arginine at codon 186 of the MLH1 protein. Computational prediction tool suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold ≥0.7, PMID: 27666373). Score = 0.926. Splice site prediction tools suggest that this variant may not impact RNA splicing. To our knowledge, functional studies have not been performed for this variant. This variant has not been reported in individuals affected with hereditary cancer in the literature. This variant has not been identified 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. -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Apr 07, 2023

This variant is not present in population databases (gnomAD no frequency). This sequence change replaces histidine, which is basic and polar, with arginine, which is basic and polar, at codon 186 of the MLH1 protein (p.His186Arg). This variant has not been reported in the literature in individuals affected with MLH1-related conditions. 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. 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 expected to disrupt MLH1 protein function. ClinVar contains an entry for this variant (Variation ID: 922704). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.92
BayesDel_addAF	Pathogenic	0.50	D
BayesDel_noAF	Pathogenic	0.48
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.81	D;.
Eigen	Pathogenic	0.69
Eigen_PC	Pathogenic	0.71
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.95	D;D
M_CAP	Uncertain	0.23	D
MetaRNN	Pathogenic	0.91	D;D
MetaSVM	Uncertain	0.45	D
MutationAssessor	Pathogenic	4.3	H;.
PrimateAI	Uncertain	0.68	T
PROVEAN	Pathogenic	-7.0	D;D
REVEL	Pathogenic	0.93
Sift	Pathogenic	0.0	D;D
Sift4G	Uncertain	0.0020	D;D
Polyphen		1.0	D;.
Vest4		0.85
MutPred		0.74		Gain of MoRF binding (P = 0.0059);.;
MVP		0.98
MPC		0.44
ClinPred		1.0	D
GERP RS		6.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.92
gMVP		0.89

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: rs1060500712; hg19: chr3-37053322;