rs63751662

Variant names:

• chr3-37048609-G-A
• rs63751662
• NM_000249.4:c.1989G>A

Your query was ambiguous. Multiple possible variants found:

• chr3-37048609-G-A
• chr3-37048609-G-C
• chr3-37048609-G-T

Variant summary

Our verdict is Pathogenic. The variant received 14 ACMG points: 14P and 0B. PM2 PP3_Strong PP5_Very_Strong

The NM_000249.4(MLH1):​c.1989G>A​(p.Glu663Glu) variant causes a splice region, synonymous change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000686 in 1,457,664 control chromosomes in the GnomAD database, with no homozygous occurrence. 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 Pathogenic (★★★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: MLH1 NM_000249.4 splice_region, synonymous
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic reviewed by expert panel P:5
• Conservation: PhyloP100: 7.39
• Publications: 19 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 14 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 3-37048609-G-A is Pathogenic according to our data. Variant chr3-37048609-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 89979.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.1989G>A	p.Glu663Glu	splice_region_variant, synonymous_variant	Exon 17 of 19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.1989G>A	p.Glu663Glu	splice_region_variant, synonymous_variant	Exon 17 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.86e-7 AC: 1 AN: 1457664 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 725506

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33382

American (AMR) AF: 0.00 AC: 0 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26102

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

South Asian (SAS) AF: 0.00 AC: 0 AN: 86172

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53310

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5760

European-Non Finnish (NFE) AF: 9.02e-7 AC: 1 AN: 1108240

Other (OTH) AF: 0.00 AC: 0 AN: 60298

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 31

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:5

Revision: reviewed by expert panel

Submissions by phenotype

Hereditary cancer-predisposing syndrome Pathogenic:2

Sep 09, 2020

Color Diagnostics, LLC DBA Color Health

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is located in the MLH1 protein at the last nucleotide of exon 17. Functional studies have shown that this variant impact splicing resulting in an in-frame deletion of exon 17 (http://www.insight-database.org/). This variant has been reported in individuals affected with Lynch syndrome (PMID: 11208710, 19419416, 21615986, 27064304, 27601186). This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Based on the available evidence, this variant is classified as Likely Pathogenic. -

Jul 18, 2024

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1989G>A variant (also known as p.E663E), located in coding exon 17 of the MLH1 gene, results from a G to A substitution at nucleotide position 1989. This nucleotide substitution does not change the at codon 663. However, this change occurs in the last base pair of coding exon 17, which makes it likely to have some effect on normal mRNA splicing. This variant has been identified in probands who met Amsterdam I/II criteria for Lynch syndrome (Tang R et al. Clin Genet, 2009 Apr;75:334-45; Wei W et al. BMB Rep, 2011 May;44:317-22), as well as a proband who met Amsterdam I criteria for Lynch syndrome and tumor demonstrated high microsatellite instability with loss of MLH1/PMS2 expression by immunohistochemistry (Ambry internal data). RNA studies have demonstrated that this alteration results in abnormal splicing in the set of samples tested (Thompson BA et al. Front Genet, 2020 Jul;11:798; Gao D et al. Nat Commun, 2021 Jun;12:3332). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration may weaken the native splice donor site and will result in the creation or strengthening of a novel splice donor site; however, direct evidence is insufficient at this time (Ambry internal data). Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Lynch syndrome 1 Pathogenic:1

Jun 13, 2018

International Society for Gastrointestinal Hereditary Tumours (InSiGHT)

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: curation

RNA studies showed loss of the c.1989A allele in the cDNA, supporting the full splicing effect of the variant leading to p.Glu633_Glu663del. -

not provided Pathogenic:1

Sep 09, 2016

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Hereditary nonpolyposis colorectal neoplasms Pathogenic:1

Feb 02, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects codon 663 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 17, which is part of the consensus splice site for this exon. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with clinical features of Lynch syndrome (PMID: 11208710, 19419416, 21615986, 27601186). ClinVar contains an entry for this variant (Variation ID: 89979). Variants that disrupt 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. This variant disrupts the c.1989G>T nucleotide in the MLH1 gene. Other variant(s) that disrupt this nucleotide have been determined to be pathogenic (PMID: 10480359, 16395668, 18561205, 21404117, 21642682, 24278394). This suggests that this nucleotide is clinically significant, and that variants that disrupt this position are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.44
CADD	Pathogenic	27
DANN	Benign	0.84
PhyloP100		7.4
Mutation Taster		=1/99	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.99
SpliceAI score (max)		0.95		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.95		Position offset: 31
DS_DL_spliceai		0.36		Position offset: 0

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

Other links and lift over

dbSNP: rs63751662; hg19: chr3-37090100;