3-36996655-TAA-TA

Variant names:

• chr3-36996655-TA-T
• rs63750028
• NM_000249.4:c.156delA

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000249.4(MLH1):​c.156delA​(p.Glu53ArgfsTer4) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,738 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: MLH1 NM_000249.4 frameshift
• Clinical Significance: Pathogenic reviewed by expert panel P:11
• Conservation: PhyloP100: 8.87
• Publications: 7 publications found

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 Gene-Disease associations (from GenCC):

• Lynch syndrome

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: G2P, ClinGen, Orphanet
• Lynch syndrome 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Genomics England PanelApp
• Muir-Torre syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Genomics England PanelApp, Ambry Genetics, G2P, Orphanet
• mismatch repair cancer syndrome 1

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Ambry Genetics, G2P, Labcorp Genetics (formerly Invitae), Orphanet, ClinGen
• Lynch syndrome 1

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• ovarian cancer

  Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
• malignant pancreatic neoplasm

  Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
• rhabdomyosarcoma

  Inheritance: AR Classification: MODERATE Submitted by: Genomics England PanelApp
• prostate cancer

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
• breast cancer

  Inheritance: AD Classification: NO_KNOWN Submitted by: Ambry Genetics
• hereditary breast carcinoma

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 3-36996655-TA-T is Pathogenic according to our data. Variant chr3-36996655-TA-T is described in ClinVar as Pathogenic. ClinVar VariationId is 89793.Status of the report is reviewed_by_expert_panel, 3 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4	c.156delA	p.Glu53ArgfsTer4	frameshift_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.156delA	p.Glu53ArgfsTer4	frameshift_variant	Exon 2 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461738 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 727166

African (AFR) AF: 0.00 AC: 0 AN: 33472

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39682

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53406

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111914

Other (OTH) AF: 0.00 AC: 0 AN: 60384

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:11

Revision: reviewed by expert panel

Submissions by phenotype

Colorectal cancer, hereditary nonpolyposis, type 2 Pathogenic:3

Aug 23, 2019

Foundation for Research in Genetics and Endocrinology, FRIGE's Institute of Human Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The heterozygous deletion c.156delA (p.Glu53ArgfsTer4) lies in exon 2 of the MLH1 gene and is predicted to cause a frameshift and consequent premature termination of the protein. The resultant protein is likely to lack the major functional domains of the protein, this will likely result in loss of function. The variant has been reported in the ClinVar database as pathogenic. The variant has been previously reported in patients affected with Lynch Syndrome and it is indicated to be disease causing. In summary, the variant meets our criteria to be classified as pathogenic. -

Jul 11, 2023

Myriad Genetics, Inc.

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered pathogenic. This variant creates a frameshift predicted to result in premature protein truncation. -

May 20, 2023

Neuberg Centre For Genomic Medicine, NCGM

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The observed frameshift variant c.156del(p.Glu53ArgfsTer4) in MLH1 gene has been reported previously with MLH1-related conditions (Espenschied CR, et al.., 2017). The c.156del variant is absent in gnomAD Exomes. This variant has been reported to the ClinVar database as Likely Pathogenic / Pathogenic. However study on multiple affected individuals and functional studies on the pathogenicity of the variant is unavailable. This variant causes a frameshift starting with codon Glutamic Acid 53, changes this amino acid to Arginine residue, and creates a premature Stop codon at position 4 of the new reading frame, denoted p.Glu53ArgfsTer4. This variant is predicted to cause loss of normal protein function through protein truncation. Loss of function variants have been previously reported to be disease causing (Casey G,et al., 2005). For these reasons, this variant has been classified as Likely Pathogenic. -

Lynch syndrome Pathogenic:3

Sep 05, 2013

International Society for Gastrointestinal Hereditary Tumours (InSiGHT)

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: research

Coding sequence variation resulting in a stop codon -

Jan 19, 2017

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: The MLH1 c.156delA (p.Glu53Argfs) 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. c.1210_1211delCT, p.Leu404fs). One in silico tool predicts a damaging outcome for this variant. This variant is absent in 121360 control chromosomes. In addition, multiple clinical diagnostic laboratories/reputable databases classified this variant as pathogenic. The variant of interest has not, to our knowledge, been reported in affected individuals via publications nor evaluated for functional impact by in vivo/vitro studies. Taken together, this variant is classified as likely pathogenic. -

Nov 16, 2021

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Glu53ArgfsX4 variant in MLH1 has been reported in an individual referred for genetic testing for Lynch Syndrome (Espenschied 2017 PMID: 28514183) and was absent from large population databases. This variant is predicted to cause a frameshift, which alters the protein’s amino acid sequence beginning at position 53 and leads to a premature termination codon 4 amino acids downstream. This alteration is then predicted to lead to a truncated or absent protein. Loss of function of the MLH1 gene is an established disease mechanism in autosomal dominant Lynch syndrome. Moreover, this variant was also classified as pathogenic on Sep 05, 2013 by the ClinGen-approved InSiGHT expert panel (Variation ID 89793). In summary, although additional studies are required to fully establish its clinical significance, this variant meets criteria to be classified as likely pathogenic for autosomal dominant Lynch syndrome. ACMG/AMP Criteria applied: PVS1, PM2_Supporting. -

Hereditary cancer-predisposing syndrome Pathogenic:2

Mar 31, 2022

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.156delA pathogenic mutation, located in coding exon 2 of the MLH1 gene, results from a deletion of one nucleotide at nucleotide position 156, causing a translational frameshift with a predicted alternate stop codon (p.E53Rfs*4). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). 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. -

Jan 28, 2021

Color Diagnostics, LLC DBA Color Health

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant deletes 1 nucleotide in exon 2 of the MLH1 gene, creating a frameshift and premature translation stop signal. This variant is expected to result in an absent or non-functional protein product. This variant has been reported in a family affected with Lynch syndrome (Elias 2017, doi.org/10.24870/cjb.2017-a238). Eight members of this family were identified as carriers, of which three members were affected (age of onset <30 years in one individual and >40 years in two individuals). This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Loss of MLH1 function is a known mechanism of disease (clinicalgenome.org). Based on the available evidence, this variant is classified as Pathogenic. -

not provided Pathogenic:1

-

Mayo Clinic Laboratories, Mayo Clinic

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Hereditary nonpolyposis colorectal neoplasms Pathogenic:1

Dec 12, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Glu53Argfs*4) in the MLH1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in MLH1 are known to be pathogenic (PMID: 15713769, 24362816). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with MLH1-related conditions (PMID: 15713769, 24362816, 28514183). Invitae Evidence Modeling of clinical and family history, age, sex, and reported ancestry of multiple individuals with this MLH1 variant has been performed. This variant is expected to be pathogenic with a positive predictive value of at least 99%. This is a validated machine learning model that incorporates the clinical features of 1,370,736 individuals referred to our laboratory for MLH1 testing. ClinVar contains an entry for this variant (Variation ID: 89793). For these reasons, this variant has been classified as Pathogenic. -

Familial cancer of breast Pathogenic:1

May 07, 2021

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		8.9
Mutation Taster		=0/200	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs63750028; hg19: chr3-37038146;