3-37011856-TA-TAA

Variant names:

• chr3-37011856-T-TA
• rs63751653
• ENST00000231790.8:c.577_578insA

Variant summary

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

The ENST00000231790.8(MLH1):​c.577_578insA​(p.Ser193ThrfsTer7) variant causes a frameshift change. The variant allele was found at a frequency of 0.00000657 in 152,190 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. S193S) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: MLH1 ENST00000231790.8 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 6.51
• Publications: 12 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 3-37011856-T-TA is Pathogenic according to our data. Variant chr3-37011856-T-TA is described in ClinVar as Pathogenic. ClinVar VariationId is 972525.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: ENST00000231790.8. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MLH1	NM_000249.4	MANE Select	c.588dupA		splice_donor intron	N/A	NP_000240.1
	MLH1	NM_001354628.2		c.588dupA		splice_donor intron	N/A	NP_001341557.1
	MLH1	NM_001354629.2		c.489dupA		splice_donor intron	N/A	NP_001341558.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MLH1	ENST00000231790.8	TSL:1 MANE Select	c.577_578insA	p.Ser193ThrfsTer7	frameshift	Exon 7 of 19	ENSP00000231790.3
	MLH1	ENST00000456676.7	TSL:1	c.577_578insA	p.Ser193ThrfsTer7	frameshift	Exon 7 of 17	ENSP00000416687.3
	MLH1	ENST00000413740.2	TSL:1	c.577_578insA	p.Ser193ThrfsTer7	frameshift	Exon 7 of 15	ENSP00000416476.2

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152190 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 30

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152190 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74374

African (AFR) AF: 0.00 AC: 0 AN: 41448

American (AMR) AF: 0.00 AC: 0 AN: 15264

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3466

East Asian (EAS) AF: 0.00 AC: 0 AN: 5204

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10620

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68036

Other (OTH) AF: 0.00 AC: 0 AN: 2092

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Colorectal cancer, hereditary nonpolyposis, type 2 Pathogenic:2

Feb 21, 2024

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Jul 17, 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.

Hereditary nonpolyposis colorectal neoplasms Pathogenic:1

Jun 04, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This premature translational stop signal has been observed in individual(s) with colorectal cancer (PMID: 21286823). For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 972525). This variant is also known as c.643_648dupA. This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Gln197Thrfs*7) 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).

Hereditary cancer-predisposing syndrome Pathogenic:1

Feb 15, 2022

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.588dupA pathogenic mutation, located in coding exon 7 of the MLH1 gene, results from a duplication of A at nucleotide position 588, causing a translational frameshift with a predicted alternate stop codon (p.Q197Tfs*7). 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 v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		6.5
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: rs63751653; hg19: chr3-37053347; COSMIC: COSV51615863; COSMIC: COSV51615863;