dbSNP rs63750226: MLH1:p.Pro496His (chr3-37028861-C-A) – ACMG Classification: Uncertain_significance (2 pts)

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_000249.4(MLH1):c.1487C>A(p.Pro496His) variant causes a missense change. The variant allele was found at a frequency of 0.00000205 in 1,461,842 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. P496L) has been classified as Benign.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0000021 ( 0 hom. )

Consequence

MLH1
NM_000249.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:3

Conservation

PhyloP100: 6.11

Variant links:

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 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4 link	c.1487C>A	p.Pro496His	missense_variant	Exon 13 of 19	ENST00000231790.8	NP_000240.1	P40692-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8 link	c.1487C>A	p.Pro496His	missense_variant	Exon 13 of 19	1	NM_000249.4	ENSP00000231790.3		P40692-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD3 exomes

AF:

0.00000795

AC:

AN:

251484

Hom.:

AF XY:

0.00000736

AC XY:

AN XY:

135914

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.000198

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:

0.00

GnomAD4 exome

AF:

0.00000205

AC:

AN:

1461842

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727222

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.0000383

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.:

Alfa

AF:

0.0000254

Hom.:

ExAC

AF:

0.0000165

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Lynch syndrome

Uncertain:1

May 30, 2024

All of Us Research Program, National Institutes of Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces proline with histidine at codon 496 of the MLH1 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with MLH1-related disorders in the literature. This variant has been identified in 2/251484 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. -

Hereditary nonpolyposis colorectal neoplasms

Uncertain:1

Sep 15, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces proline, which is neutral and non-polar, with histidine, which is basic and polar, at codon 496 of the MLH1 protein (p.Pro496His). This variant is present in population databases (rs63750226, gnomAD 0.02%). 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: 577560). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed for this missense variant. However, the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on MLH1 protein function. 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

Feb 14, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.P496H variant (also known as c.1487C>A), located in coding exon 13 of the MLH1 gene, results from a C to A substitution at nucleotide position 1487. The proline at codon 496 is replaced by histidine, an amino acid with 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. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.27

BayesDel_addAF

Pathogenic

0.41

BayesDel_noAF

Pathogenic

0.35

CADD

Pathogenic

DANN

Uncertain

1.0

DEOGEN2

Uncertain

0.68

D;.;.;.;.;.;T;T

Eigen

Uncertain

0.42

Eigen_PC

Uncertain

0.46

FATHMM_MKL

Uncertain

0.94

LIST_S2

Uncertain

0.94

D;D;.;.;.;D;D;D

M_CAP

Uncertain

0.18

MetaRNN

Uncertain

0.63

D;D;D;D;D;D;D;D

MetaSVM

Uncertain

0.49

MutationAssessor

Uncertain

2.7

M;.;.;.;.;.;.;.

PrimateAI

Uncertain

0.57

PROVEAN

Uncertain

-3.8

D;D;D;D;D;D;D;D

REVEL

Pathogenic

0.67

Sift

Uncertain

0.0040

D;D;D;D;D;D;D;D

Sift4G

Uncertain

0.040

D;D;D;D;D;D;D;D

Polyphen

1.0

D;.;.;.;.;.;.;.

Vest4

0.63

MutPred

0.30

Loss of helix (P = 0.0093);.;.;.;.;.;.;.;

MVP

0.92

MPC

0.098

ClinPred

0.90

GERP RS

5.9

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

Varity_R

0.61

gMVP

0.38

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over