3-37042331-G-T

Variant names:

• chr3-37042331-G-T
• rs63751657
• NM_000249.4:c.1731G>T

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM2 PP3 PP5_Very_Strong

The NM_000249.4(MLH1):​c.1731G>T​(p.Ser577Ser) variant causes a splice region, synonymous change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. S577S) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: MLH1 NM_000249.4 splice_region, synonymous
• Scores: Splicing: ADA: 0.9698
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 0.502
• Publications: 40 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 11 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 3-37042331-G-T is Pathogenic according to our data. Variant chr3-37042331-G-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 525656.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000249.4. 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.1731G>T	p.Ser577Ser	splice_region synonymous	Exon 15 of 19	NP_000240.1
	MLH1	NM_001354628.2		c.1731G>T	p.Ser577Ser	splice_region synonymous	Exon 15 of 18	NP_001341557.1
	MLH1	NM_001354629.2		c.1632G>T	p.Ser544Ser	splice_region synonymous	Exon 14 of 18	NP_001341558.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MLH1	ENST00000231790.8	TSL:1 MANE Select	c.1731G>T	p.Ser577Ser	splice_region synonymous	Exon 15 of 19	ENSP00000231790.3
	MLH1	ENST00000456676.7	TSL:1	c.1731G>T	p.Ser577Ser	splice_region synonymous	Exon 15 of 17	ENSP00000416687.3
	MLH1	ENST00000458205.6	TSL:1	c.1008G>T	p.Ser336Ser	splice_region synonymous	Exon 16 of 20	ENSP00000402667.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1443522 Hom.: 0 Cov.: 29 AF XY: 0.00 AC XY: 0 AN XY: 719466

African (AFR) AF: 0.00 AC: 0 AN: 33098

American (AMR) AF: 0.00 AC: 0 AN: 44700

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26034

East Asian (EAS) AF: 0.00 AC: 0 AN: 39614

South Asian (SAS) AF: 0.00 AC: 0 AN: 85886

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53334

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5736

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1095332

Other (OTH) AF: 0.00 AC: 0 AN: 59788

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Colorectal cancer, hereditary nonpolyposis, type 2 Pathogenic:1

Jun 09, 2023

Myriad Genetics, Inc.

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered pathogenic. This variant is strongly associated with more severe personal and family histories of cancer, typical for individuals with pathogenic variants in this gene [PMID: 25085752, 27363726]. mRNA analysis has demonstrated abnormal mRNA splicing occurs [Myriad internal data].

Hereditary nonpolyposis colorectal neoplasms Pathogenic:1

Jun 11, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects codon 577 of the MLH1 mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the MLH1 protein. This variant also falls at the last nucleotide of exon 15, which is part of the consensus splice site for this exon. This variant is not present in population databases (ExAC no frequency). This variant has been observed in individual(s) with clinical features of Lynch syndrome (PMID: 28135145, 25110875, Invitae). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 525656). Nucleotide substitutions within the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site, but this prediction has not been confirmed by published transcriptional studies. This variant disrupts the c.1731G nucleotide in the MLH1 gene. Other variant(s) that disrupt this nucleotide have been determined to be pathogenic (PMID: 16341550, 15849733, 20223024, 18561205, 16451135). This suggests that this nucleotide is clinically significant, and that variants that disrupt this position are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic.

Hereditary cancer-predisposing syndrome Pathogenic:1

Jun 24, 2020

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1731G>T variant (also known as p.S577S), located in coding exon 15 of the MLH1 gene, results from a G to T substitution at nucleotide position 1731. This nucleotide substitution does not change the amino acid at codon 577. However, this change occurs in the last base pair of coding exon 15, which makes it likely to have some effect on normal mRNA splicing. Another variant at the same nucleotide position, c.1731G>A, has been reported as pathogenic based on being identified in several probands who met Amsterdam criteria for Lynch syndrome and had loss of MLH1 expression on immunohistochemistry in their tumors (Pistorius SR et al. Int. J. Colorectal Dis. 2000 Nov;15(5-6):255-63; Mangold E et al. Int. J. Cancer. 2005 Sep;116(5):692-702; Jasperson KW et al. Fam. Cancer, 2010 Jun;9:99-107). In addition, splicing data reported in multiple studies demonstrate out-of-frame exon 15 skipping for the c.1731G>A variant (Kohonen-Corish M et al. Am. J. Hum. Genet. 1996 Oct;59(4):818-24; Auclair J et al. Hum. Mutat. 2006 Feb;27(2):145-54; Pagenstecher C et.al. Hum. Genet. 2006 Mar;119:9-22; Tournier I et al. Hum. Mutat. 2008 Dec;29(12):1412-24). This variant was not reported in population-based cohorts in the Genome Aggregation Database (gnomAD). This nucleotide position is highly conserved through mammals, but not in all available vertebrate species. Using the BDGP and ESEfinder splice site prediction tools, this alteration is predicted to weaken the efficiency of the native splice donor site; however, direct evidence is unavailable. Based on the majority of available evidence to date, this variant is likely to be pathogenic.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.36
CADD	Benign	20
DANN	Benign	0.86
PhyloP100		0.50
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.8

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.97
dbscSNV1_RF	Pathogenic	0.79
SpliceAI score (max)		0.64		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.64		Position offset: 0

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs63751657; hg19: chr3-37083822;