3-36996624-A-T

Variant names:

• chr3-36996624-A-T
• rs63751094
• ENST00000458205:c.-747A>T

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PM2 PP3_Strong PP5_Very_Strong

The NM_001167617.3(MLH1):​c.-168A>T variant causes a 5 prime UTR premature start codon gain 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 Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: MLH1 NM_001167617.3 5_prime_UTR_premature_start_codon_gain
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 8.87

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 Pathogenic. Variant got 14 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.991
• PP5: Variant 3-36996624-A-T is Pathogenic according to our data. Variant chr3-36996624-A-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 455379.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4	c.122A>T	p.Asp41Val	missense_variant	Exon 2 of 19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.122A>T	p.Asp41Val	missense_variant	Exon 2 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Colorectal cancer, hereditary nonpolyposis, type 2 Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 24, 2024	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Jul 18, 2023	This variant is considered likely pathogenic. This variant is strongly associated with more severe personal and family histories of cancer, typical for individuals with pathogenic variants in this gene [PMID: 27363726]. -

Hereditary nonpolyposis colorectal neoplasms Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 18, 2023

This sequence change replaces aspartic acid, which is acidic and polar, with valine, which is neutral and non-polar, at codon 41 of the MLH1 protein (p.Asp41Val). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with Lynch syndrome (PMID: 19419416; Invitae). ClinVar contains an entry for this variant (Variation ID: 455379). 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. This variant disrupts the p.Asp41 amino acid residue in MLH1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 12624141, 25060679, 25477341). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Hereditary cancer-predisposing syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Jul 14, 2022

The p.D41V pathogenic mutation (also known as c.122A>T), located in coding exon 2 of the MLH1 gene, results from an A to T substitution at nucleotide position 122. The aspartic acid at codon 41 is replaced by valine, an amino acid with highly dissimilar properties. This variant has been detected in multiple families meeting Amsterdam I criteria (Ambry internal data). Based on internal structural analysis, p.D41V is structurally deleterious (Ambry internal data; Wu H et al. Acta Crystallogr F Struct Biol Commun, 2015 Aug;71:981-5). An alteration resulting in the same amino acid change, p.D41V (c.122_123delATinsTA) has been reported in 1 of 93 unrelated Taiwanese families that fulfilled the Amsterdam II criteria with concordant MSI and/or IHC, and was not found in 300 controls (Tang R et al, Clin. Genet. 2009 Apr; 75(4):334-45). Further, an alteration at the same codon, p.D41G (c.122A>G) has been classified as pathogenic by multifactorial analysis, which integrates the following lines of evidence to produce a quantitative likelihood of pathogenicity: in silico prediction models, segregation with disease, clinical phenotype including tumor characteristics, mutation co-occurrence, and functional assay results (Thompson B et al. Nat Genet. 2014 Feb;46(2):107-15; available at [www.insight-group.org/variants/classifications/]). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.54	D
BayesDel_noAF	Pathogenic	0.54
CADD	Pathogenic	32
DANN	Benign	0.88
DEOGEN2	Pathogenic	0.97	D
Eigen	Pathogenic	0.83
Eigen_PC	Pathogenic	0.79
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Pathogenic	0.59	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	0.87	D
MutationAssessor	Pathogenic	5.0	H
PrimateAI	Uncertain	0.72	T
PROVEAN	Pathogenic	-7.9	D
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.96
MutPred		0.94		Gain of catalytic residue at D41 (P = 0.1088);
MVP		0.99
MPC		0.48
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.98
gMVP		0.93

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: rs63751094; hg19: chr3-37038115;