3-37020432-G-C

Position:

• chr3-37020432-G-C

Variant summary

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

The NM_000249.4(MLH1):​c.1007G>C​(p.Gly336Ala) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,882 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 9.29

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 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MLH1	NM_000249.4	c.1007G>C	p.Gly336Ala	missense_variant	11/19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.1007G>C	p.Gly336Ala	missense_variant	11/19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461882 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727242

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Jan 10, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	Feb 13, 2023	The p.G336A variant (also known as c.1007G>C), located in coding exon 11 of the MLH1 gene, results from a G to C substitution at nucleotide position 1007. The glycine at codon 336 is replaced by alanine, an amino acid with similar properties. 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. -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 04, 2023

This sequence change replaces glycine, which is neutral and non-polar, with alanine, which is neutral and non-polar, at codon 336 of the MLH1 protein (p.Gly336Ala). 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: 573568). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.28
BayesDel_addAF	Pathogenic	0.47	D
BayesDel_noAF	Pathogenic	0.43
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.63	D;.;.;.;.;.;.
Eigen	Uncertain	0.57
Eigen_PC	Uncertain	0.64
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Pathogenic	0.99	D;D;.;.;.;D;D
M_CAP	Uncertain	0.17	D
MetaRNN	Uncertain	0.72	D;D;D;D;D;D;D
MetaSVM	Uncertain	0.62	D
MutationAssessor	Uncertain	2.3	M;.;.;.;.;.;.
PrimateAI	Uncertain	0.61	T
PROVEAN	Uncertain	-3.1	D;D;D;D;D;D;D
REVEL	Uncertain	0.64
Sift	Benign	0.061	T;T;T;T;T;T;T
Sift4G	Benign	0.20	T;T;T;T;T;T;T
Polyphen		0.77	P;.;.;.;.;.;.
Vest4		0.68
MutPred		0.18		Loss of ubiquitination at K333 (P = 0.0683);.;.;.;.;.;.;
MVP		0.98
MPC		0.20
ClinPred		0.95	D
GERP RS		5.2
Varity_R		0.59
gMVP		0.37

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: rs587781750; hg19: chr3-37061923;