3-37008839-C-G

Position:

• chr3-37008839-C-G

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PM5

The NM_000249.4(MLH1):​c.479C>G​(p.Ala160Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. A160S) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 2.61

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 17 uncertain in NM_000249.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr3-37008839-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MLH1	NM_000249.4	c.479C>G	p.Ala160Gly	missense_variant	6/19	ENST00000231790.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MLH1	ENST00000231790.8	c.479C>G	p.Ala160Gly	missense_variant	6/19	1	NM_000249.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

May 29, 2022

This sequence change replaces alanine, which is neutral and non-polar, with glycine, which is neutral and non-polar, at codon 160 of the MLH1 protein (p.Ala160Gly). This variant is not present in population databases (gnomAD no frequency). 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: 483582). 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 not expected to disrupt 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

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Apr 13, 2017

The p.A160G variant (also known as c.479C>G), located in coding exon 6 of the MLH1 gene, results from a C to G substitution at nucleotide position 479. The alanine at codon 160 is replaced by glycine, an amino acid with similar properties. This amino acid position is poorly 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.090
BayesDel_addAF	Uncertain	0.15	D
BayesDel_noAF	Uncertain	-0.020
CADD	Benign	21
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.45	T;.;T
Eigen	Benign	0.12
Eigen_PC	Uncertain	0.24
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.87	D;D;D
M_CAP	Benign	0.018	T
MetaRNN	Uncertain	0.44	T;T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	1.1	L;.;.
MutationTaster	Benign	1.0	D;D;D;D;N;N
PrimateAI	Benign	0.35	T
PROVEAN	Benign	-1.1	N;N;N
REVEL	Uncertain	0.47
Sift	Benign	0.11	T;T;D
Sift4G	Benign	0.096	T;T;D
Polyphen		0.0	B;.;.
Vest4		0.31
MutPred		0.75		Loss of ubiquitination at K164 (P = 0.1037);.;.;
MVP		0.98
MPC		0.067
ClinPred		0.26	T
GERP RS		4.3
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.7
Varity_R		0.052
gMVP		0.54

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		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: rs63749924; hg19: chr3-37050330;