Our verdict is Uncertain significance. Variant got 0 ACMG points: 0P and 0B.
The NM_000249.4(MLH1):c.452C>T(p.Thr151Met) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000807 in 1,611,316 control chromosomes in the GnomAD database, with no homozygous occurrence. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
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]
Uncertain significance, criteria provided, single submitter
clinical testing
Quest Diagnostics Nichols Institute San Juan Capistrano
Nov 09, 2022
The frequency of this variant in the general population, 0.000087 (3/34588 chromosomes, http://gnomad.broadinstitute.org), is uninformative in assessment of its pathogenicity. In the published literature, the variant has been reported in individuals with breast cancer (PMID: 33471991 (2021) and colorectal cancer (PMID: 32658311 (2021)). Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded predictions that this variant is benign. Based on the available information, we are unable to determine the clinical significance of this variant. -
Uncertain significance, criteria provided, single submitter
clinical testing
CeGaT Center for Human Genetics Tuebingen
Jun 01, 2023
- -
Uncertain significance, criteria provided, single submitter
clinical testing
GeneDx
Aug 07, 2023
Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis, which includes protein predictors and evolutionary conservation, supports a deleterious effect; Has not been previously published as pathogenic or benign to our knowledge; This variant is associated with the following publications: (PMID: 22753075, 30122538) -
Uncertain significance, criteria provided, single submitter
clinical testing
Color Diagnostics, LLC DBA Color Health
Apr 06, 2023
This missense variant replaces threonine with methionine at codon 151 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 4/251398 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. -
Uncertain significance, criteria provided, single submitter
clinical testing
Ambry Genetics
Aug 07, 2023
The p.T151M variant (also known as c.452C>T), located in coding exon 5 of the MLH1 gene, results from a C to T substitution at nucleotide position 452. The threonine at codon 151 is replaced by methionine, an amino acid with similar properties. This amino acid position is not well conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -
Colorectal cancer, hereditary nonpolyposis, type 2 Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
Baylor Genetics
Oct 03, 2023
- -
Lynch syndrome Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
All of Us Research Program, National Institutes of Health
Dec 01, 2023
This missense variant replaces threonine with methionine at codon 151 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). Splice site prediction tools suggest that this variant may not impact RNA splicing. To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with hereditary cancer in the literature. This variant has been identified in 4/251398 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. -
MLH1-related disorder Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
PreventionGenetics, part of Exact Sciences
Jul 13, 2023
The MLH1 c.452C>T variant is predicted to result in the amino acid substitution p.Thr151Met. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.0087% of alleles in individuals of Latino descent in gnomAD (http://gnomad.broadinstitute.org/variant/3-37048553-C-T). It has conflicting interpretations of benign and uncertain significance in ClinVar (https://preview.ncbi.nlm.nih.gov/clinvar/variation/186027/), At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -
Uncertain significance, criteria provided, single submitter
clinical testing
Labcorp Genetics (formerly Invitae), Labcorp
Dec 24, 2023
This sequence change replaces threonine, which is neutral and polar, with methionine, which is neutral and non-polar, at codon 151 of the MLH1 protein (p.Thr151Met). This variant is present in population databases (rs776969475, gnomAD 0.009%). 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: 186027). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Not Available"; PolyPhen-2: "Benign"; Align-GVGD: "Not Available". The methionine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect 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. -
Ovarian cancer Benign:1
Benign, criteria provided, single submitter
clinical testing
Laboratory of Molecular Epidemiology of Birth Defects, West China Second University Hospital, Sichuan University