3-37012009-A-C

Position:

• chr3-37012009-A-C

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PVS1 PP4 PM2_Supporting

This summary comes from the ClinGen Evidence Repository: The (M_000249.4):c.589-2A>C variant in MLH1 occurs within the canonical splice acceptor site (-2) of intron 7. It is predicted to alter the consensus acceptor splice site leading to exon skipping or use of a cryptic splice site disrupting reading frame and predicting to undergo NMD (PVS1). This variant has been detected in at least one CRC MSI-H tumour with loss of MLH1 and PMS2 expression (PP4). This variant is absent from gnomAD v2.1.1 and gnomAD v4.1 (PM2_supporting).In summary, this variant meets the criteria to be classified as pathogenic for Lynch Syndrome, based on the MMR gene specific ACMG/AMP criteria established by the ClinGen InSiGHT Hereditary Colorectal Cancer/ Polyposis VCEP: PVS1, PM2_Sup, PP4 (VCEP specifications version 1). LINK:https://erepo.genome.network/evrepo/ui/classification/CA352042278/MONDO:0005835/115

• Frequency: Genomes: not found (cov: 32)
• Consequence: MLH1 NM_000249.4 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 8.78

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]

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MLH1	NM_000249.4	c.589-2A>C		splice_acceptor_variant		ENST00000231790.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MLH1	ENST00000231790.8	c.589-2A>C		splice_acceptor_variant		1	NM_000249.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Lynch syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

University of Washington Department of Laboratory Medicine, University of Washington

May 01, 2018

MLH1 NM_000249.3:c.589-2A>C has a 98.1% probability of pathogenicity based on combining prior probability from public data with a likelihood ratio of 1.56 to 1, generated from evidence of seeing this as a somatic mutation in a tumor without loss of heterozygosity at the MLH1 locus. See Shirts et al 2018, PMID 29887214. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.17
CADD	Pathogenic	34
DANN	Uncertain	0.98
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.93
FATHMM_MKL	Pathogenic	1.0	D
MutationTaster	Benign	1.0	D;D;D;D;D;D
GERP RS		4.2

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.64		Position offset: 6
DS_AL_spliceai		0.99		Position offset: 2

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

Publications

LitVar

Other links and lift over

dbSNP: rs267607767; hg19: chr3-37053500;