rs267607798

Variant names:

• chr3-37014544-CG-C
• rs267607798
• NM_000249.4:c.790+1delG

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000249.4(MLH1):​c.790+1delG variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: MLH1 NM_000249.4 splice_donor, intron
• Clinical Significance: Pathogenic reviewed by expert panel P:3
• Conservation: PhyloP100: 9.57

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 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 3-37014544-CG-C is Pathogenic according to our data. Variant chr3-37014544-CG-C is described in ClinVar as [Pathogenic]. Clinvar id is 90358.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr3-37014544-CG-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4	c.790+1delG		splice_donor_variant, intron_variant	Intron 9 of 18	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.790+1delG		splice_donor_variant, intron_variant	Intron 9 of 18	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 24

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: reviewed by expert panel

Submissions by phenotype

Lynch-like syndrome Pathogenic:1

Jul 01, 2019

Constitutional Genetics Lab, Leon Berard Cancer Center

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Lynch syndrome Pathogenic:1

Sep 05, 2013

International Society for Gastrointestinal Hereditary Tumours (InSiGHT)

Significance: Pathogenic

Review Status: reviewed by expert panel

Collection Method: research

Multifactorial likelihood analysis posterior probability >0.99 -

Hereditary cancer-predisposing syndrome Pathogenic:1

Jul 15, 2016

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.790+1delG intronic pathogenic mutation is located one nucleotide after coding exon 9 and results from the deletion of one nucleotide (G) within intron 9 of the MLH1 gene. This alteration has been reported in multiple individuals and families with Lynch syndrome related tumors. Furthermore, results from immunohistochemistry and microsatellite instability analyses in probands from these reported families were consistent with an MLH1 gene mutation (Mangold E et al. Int J Cancer. 2005 Sep 20;116(5):692-702; Mueller-Koch Y et al. Gut. 2005 Dec;54(12):1733-40). In addition to the clinical data presented in the literature, alterations that disrupt the canonical splice site are expected to cause aberrant splicing, resulting in an abnormal protein or a transcript that is subject to nonsense-mediated mRNA decay. As such, this alteration is classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.87		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.87		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs267607798; hg19: chr3-37056035;