NM_000249.4:c.1265G>A

Variant names:

• chr3-37025863-G-A
• rs1553651162
• NM_000249.4:c.1265G>A

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_000249.4(MLH1):​c.1265G>A​(p.Gly422Asp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 14/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. G422G) has been classified as Benign.

• Frequency: Genomes: not found (cov: 31)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 1.44

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 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.08638883).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4	c.1265G>A	p.Gly422Asp	missense_variant	Exon 12 of 19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.1265G>A	p.Gly422Asp	missense_variant	Exon 12 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:2

Sep 25, 2024

Molecular Diagnostics Laboratory, Catalan Institute of Oncology

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

PM2_Supporting, BP4 c.1265G>A, located in exon 12 of the MLH1 gene, is predicted to result in the substitution of Gly by Asp at codon 422, p.(Gly422Asp). It is not present in the population database gnomAD v2.1.1, non cancer dataset (PM2_supporting). Computational tools for this variant suggests no significant impact on splicing and does not affect the protein function (MAPP+PolyPhen-2 prior probability for pathogenicity: 0.015) (BP4). To our knowledge, neither individuals with Lynch syndrome-related conditions nor functional studies have been reported in the literature for this variant. There are no reports of pathogenic missense variants in the same codon. In addition, this variant has been reported in the ClinVar database (3x uncertain significance) but it has not been identified neither in LOVD nor InSiGHT databases. Based on currently available information, the variant c.1265G>A should be considered an uncertain significance variant. -

May 15, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.G422D variant (also known as c.1265G>A), located in coding exon 12 of the MLH1 gene, results from a G to A substitution at nucleotide position 1265. The glycine at codon 422 is replaced by aspartic acid, an amino acid with similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be tolerated by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear. -

not provided Uncertain:1

Jul 13, 2023

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant has not been reported in individuals with MLH1-related conditions in the published literature. It also has not been reported in large, multi-ethnic general populations (Genome Aggregation Database, http://gnomad.broadinstitute.org). 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. -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Dec 06, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine with aspartic acid at codon 422 of the MLH1 protein (p.Gly422Asp). The glycine residue is weakly conserved and there is a moderate physicochemical difference between glycine and aspartic acid. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with MLH1-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.063
BayesDel_addAF	Uncertain	0.032	T
BayesDel_noAF	Benign	-0.19
CADD	Benign	13
DANN	Benign	0.76
DEOGEN2	Benign	0.32	T;.;.;.;.;.
Eigen	Benign	-1.1
Eigen_PC	Benign	-1.0
FATHMM_MKL	Benign	0.14	N
LIST_S2	Benign	0.63	T;T;.;.;.;T
M_CAP	Benign	0.031	D
MetaRNN	Benign	0.086	T;T;T;T;T;T
MetaSVM	Benign	-0.79	T
MutationAssessor	Benign	0.83	L;.;.;.;.;.
PrimateAI	Benign	0.25	T
PROVEAN	Benign	-1.2	N;N;N;N;N;N
REVEL	Uncertain	0.52
Sift	Benign	0.54	T;T;T;T;T;T
Sift4G	Benign	0.40	T;T;T;T;T;T
Polyphen		0.0	B;.;.;.;.;.
Vest4		0.32
MutPred		0.28		Loss of glycosylation at S421 (P = 0.0418);.;.;.;.;.;
MVP		0.97
MPC		0.085
ClinPred		0.016	T
GERP RS		2.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.029
gMVP		0.28

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: rs1553651162; hg19: chr3-37067354;