Submissions for variant NM_000249.4(MLH1):c.928A>G (p.Thr310Ala)

gnomAD frequency: 0.00002  dbSNP: rs779581111

Total submissions: 11

Submitter	RCV	SCV	Clinical significance	Condition	Last evaluated	Review status	Method	Comment
Labcorp Genetics (formerly Invitae), Labcorp	RCV000234748	SCV000284082	likely benign	Hereditary nonpolyposis colorectal neoplasms	2025-01-19	criteria provided, single submitter	clinical testing
GeneDx	RCV000759816	SCV000618479	uncertain significance	not provided	2017-05-15	criteria provided, single submitter	clinical testing	This variant is denoted MLH1 c.928A>G at the cDNA level, p.Thr310Ala (T310A) at the protein level, and results in the change of a Threonine to an Alanine (ACA>GCA). This variant has not, to our knowledge, been published in the literature as pathogenic or benign. MLH1 Thr310Ala was observed at an allele frequency of 0.02% (3/11578) in individuals of Latino ancestry in large population cohorts (NHLBI Exome Sequencing Project, The 1000 Genomes Consortium 2015, Lek 2016). Since Threonine and Alanine differ in polarity, charge, size or other properties, this is considered a non-conservative amino acid substitution. MLH1 Thr310Ala occurs at a position that is conserved across species and is located within the N-terminal ATPase domain (Andersen 2012). In silico analyses predict that this variant is probably damaging to protein structure and function. Based on currently available evidence, it is unclear whether MLH1 Thr310Ala is a pathogenic or benign variant. We consider it to be a variant of uncertain significance.
Color Diagnostics, LLC DBA Color Health	RCV000581030	SCV000684883	uncertain significance	Hereditary cancer-predisposing syndrome	2023-01-23	criteria provided, single submitter	clinical testing	This missense variant replaces threonine with alanine at codon 310 of the MLH1 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in an individual affected with colorectal cancer (PMID: 32973888). This variant has been identified in 6/251418 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.
Quest Diagnostics Nichols Institute San Juan Capistrano	RCV000759816	SCV000889410	uncertain significance	not provided	2024-07-29	criteria provided, single submitter	clinical testing	The MLH1 c.928A>G (p.Thr310Ala) variant has been reported in the published literature in an individual with colorectal cancer (PMID: 32973888 (2020)). The frequency of this variant in the general population, 0.00017 (6/34590 chromosomes (Genome Aggregation Database, http://gnomad.broadinstitute.org)), is uninformative in the assessment of its pathogenicity. 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 damaging. Based on the available information, we are unable to determine the clinical significance of this variant.
Women's Health and Genetics/Laboratory Corporation of America, LabCorp	RCV000780417	SCV000917649	uncertain significance	not specified	2024-01-15	criteria provided, single submitter	clinical testing	Variant summary: MLH1 c.928A>G (p.Thr310Ala) results in a non-conservative amino acid change located in the DNA mismatch repair protein, S5 domain 2-like domain (IPR013507) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 2.4e-05 in 251418 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.928A>G has been reported in the literature in at least one individual affected with colorectal cancer and MMR deficiency (e.g., Xu_2020). These data do not allow any conclusion about variant significance. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication have been ascertained in the context of this evaluation (PMID: 32973888). ClinVar contains an entry for this variant (Variation ID: 237351). Based on the evidence outlined above, the variant was classified as uncertain significance.
Illumina Laboratory Services, Illumina	RCV001147025	SCV001307792	uncertain significance	Colorectal cancer, hereditary nonpolyposis, type 2	2018-01-13	criteria provided, single submitter	clinical testing	This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease.
Ambry Genetics	RCV000581030	SCV002686537	uncertain significance	Hereditary cancer-predisposing syndrome	2024-03-21	criteria provided, single submitter	clinical testing	The p.T310A variant (also known as c.928A>G), located in coding exon 11 of the MLH1 gene, results from an A to G substitution at nucleotide position 928. The threonine at codon 310 is replaced by alanine, an amino acid with similar properties. This variant was identified in a 32 year old male with MMR-deficient colorectal cancer, but specific results from IHC analysis were not provided by the authors (Xu Y et al. Front Genet, 2020 Aug;11:991). 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.
Myriad Genetics, Inc.	RCV001147025	SCV004018636	likely benign	Colorectal cancer, hereditary nonpolyposis, type 2	2023-11-14	criteria provided, single submitter	clinical testing	This variant is considered likely benign. This variant is strongly associated with less severe personal and family histories of cancer, typical for individuals without pathogenic variants in this gene [PMID: 27363726].
All of Us Research Program, National Institutes of Health	RCV003998746	SCV004840925	uncertain significance	Lynch syndrome	2024-08-23	criteria provided, single submitter	clinical testing	This missense variant replaces threonine with alanine at codon 310 of the MLH1 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in an individual affected with early onset and mismatch repair deficient colorectal cancer (PMID: 32973888). This variant has been identified in 6/251418 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.
Baylor Genetics	RCV001147025	SCV005057942	uncertain significance	Colorectal cancer, hereditary nonpolyposis, type 2	2024-03-28	criteria provided, single submitter	clinical testing
Fulgent Genetics, Fulgent Genetics	RCV005025380	SCV005662508	uncertain significance	Mismatch repair cancer syndrome 1; Muir-Torré syndrome; Colorectal cancer, hereditary nonpolyposis, type 2	2024-04-12	criteria provided, single submitter	clinical testing