rs63749995

Positions:

• chr3-37048998-C-A
• chr3-37048998-C-G
• chr3-37048998-C-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000249.4(MLH1):​c.2084C>A​(p.Ser695*) variant causes a stop gained change. 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 Pathogenic (★★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: MLH1 NM_000249.4 stop_gained
• Clinical Significance: Pathogenic reviewed by expert panel P:6
• Conservation: PhyloP100: 4.02

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 Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most 50 bp of the penultimate exon, not predicted to undergo nonsense mediated mRNA decay. There are 28 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 3-37048998-C-A is Pathogenic according to our data. Variant chr3-37048998-C-A is described in ClinVar as [Pathogenic]. Clinvar id is 90038.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr3-37048998-C-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MLH1	NM_000249.4	c.2084C>A	p.Ser695*	stop_gained	18/19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.2084C>A	p.Ser695*	stop_gained	18/19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1461362 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727030

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:6

Revision: reviewed by expert panel

Submissions by phenotype

Colorectal cancer, hereditary nonpolyposis, type 2 Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Jul 25, 2023	This variant is considered pathogenic. This variant creates a termination codon and is predicted to result in premature protein truncation. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Feb 29, 2024	- -

Lynch syndrome Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Oct 27, 2016	Variant summary: The MLH1 c.2084C>A (p.Ser695X) variant results in a premature termination codon, predicted to cause a truncated or absent MLH1 protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory (e.g.: p.Trp714X, p.His727fsX55). Mutation taster predicts a damaging outcome for this variant. This variant is absent in 120582 control chromosomes. The variant of interest has not, to our knowledge, been reported in affected individuals via publications and/or reputable databases/clinical diagnostic laboratories; nor evaluated for functional impact by in vivo/vitro studies. Multiple clinical diagnostic laboratories/reputable databases classified this variant as pathogenic. Taken together, this variant is classified as likely pathogenic. -
Pathogenic, reviewed by expert panel	research	International Society for Gastrointestinal Hereditary Tumours (InSiGHT)	Sep 05, 2013	Coding sequence variation resulting in a stop codon -

Hereditary nonpolyposis colorectal neoplasms Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 10, 2023

This sequence change creates a premature translational stop signal (p.Ser695*) in the MLH1 gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 62 amino acid(s) of the MLH1 protein. This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with Lynch syndrome (PMID: 17505997). ClinVar contains an entry for this variant (Variation ID: 90038). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. This variant disrupts a region of the MLH1 protein in which other variant(s) (p.Lys751Serfs*3) have been determined to be pathogenic (PMID: 8797773, 18566915, 18931482, 24802709, 27295708). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it 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

Apr 11, 2022

The p.S695* pathogenic mutation (also known as c.2084C>A), located in coding exon 18 of the MLH1 gene, results from a C to A substitution at nucleotide position 2084. This changes the amino acid from a serine to a stop codon within coding exon 18. This alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. As such, this alteration is interpreted as a disease-causing mutation. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	40
DANN	Uncertain	0.99
Eigen	Pathogenic	0.87
Eigen_PC	Pathogenic	0.75
FATHMM_MKL	Uncertain	0.96	D
Vest4		0.83
GERP RS		5.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.14		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: rs63749995; hg19: chr3-37090489;