3-37008842-C-T

Position:

• chr3-37008842-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_001167618.3(MLH1):​c.-242C>T variant causes a 5 prime UTR premature start codon gain change. The variant allele was found at a frequency of 0.00000342 in 1,461,784 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: MLH1 NM_001167618.3 5_prime_UTR_premature_start_codon_gain
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 6.99

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]

MLH1 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.759

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MLH1	NM_000249.4	c.482C>T	p.Thr161Met	missense_variant	6/19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.482C>T	p.Thr161Met	missense_variant	6/19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000159 AC: 4 AN: 251380 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135856

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.0000462

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461784 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727200

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.0000187

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ExAC AF: 0.0000247 AC: 3

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Lynch syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

University of Washington Department of Laboratory Medicine, University of Washington

May 01, 2018

MLH1 NM_000249.3:c.482C>T has a 14.6% probability of pathogenicity based on combining prior probability from public data with a likelihood ratio of 1.56 to 1, generated from evidence of seeing this as a somatic mutation in a tumor without loss of heterozygosity at the MLH1 locus. See Shirts et al 2018, PMID 29887214. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Aug 29, 2022

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Observed in an individual undergoing multi-gene cancer panel testing due to a personal history of a Lynch syndrome-related cancer and/or polyps (Yurgelun et al., 2015); This variant is associated with the following publications: (PMID: 29887214, 34416543, 22753075, 25980754) -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 09, 2022

This sequence change replaces threonine, which is neutral and polar, with methionine, which is neutral and non-polar, at codon 161 of the MLH1 protein (p.Thr161Met). This variant is present in population databases (rs763992299, gnomAD 0.004%). This missense change has been observed in individual(s) with a history of Lynch syndrome-associated cancer and/or colorectal polyps (PMID: 25980754). ClinVar contains an entry for this variant (Variation ID: 421591). 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

Sep 11, 2024

The p.T161M variant (also known as c.482C>T), located in coding exon 6 of the MLH1 gene, results from a C to T substitution at nucleotide position 482. The threonine at codon 161 is replaced by methionine, an amino acid with similar properties. This alteration was identified in a cohort of 1260 individuals undergoing panel testing for Lynch syndrome due to having a diagnosis of a Lynch-associated cancer and/or polyps (Yurgelun MB et al. Gastroenterology, 2015 Sep;149:604-13.e20). In addition, using a Bayesian analysis that incorporates tumor mutation data, this alteration was classified as a variant of unknown significance (Shirts BH et al. Am J Hum Genet, 2018 07;103:19-29). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Pathogenic	0.33	D
BayesDel_noAF	Pathogenic	0.32
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.76	D;.;T
Eigen	Pathogenic	0.71
Eigen_PC	Pathogenic	0.76
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	D;D;D
M_CAP	Benign	0.041	D
MetaRNN	Pathogenic	0.76	D;D;D
MetaSVM	Uncertain	0.51	D
MutationAssessor	Uncertain	2.5	M;.;.
PrimateAI	Uncertain	0.73	T
PROVEAN	Uncertain	-3.5	D;D;D
REVEL	Uncertain	0.61
Sift	Benign	0.081	T;D;T
Sift4G	Benign	0.091	T;T;T
Polyphen		0.95	P;.;.
Vest4		0.78
MutPred		0.56		Loss of phosphorylation at T161 (P = 0.029);.;.;
MVP		0.94
MPC		0.18
ClinPred		0.67	D
GERP RS		6.2
Varity_R		0.15
gMVP		0.84

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs763992299; hg19: chr3-37050333;