rs267607750

Positions:

• chr3-37007064-G-A
• chr3-37007064-G-C
• chr3-37007064-G-T

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1_Moderate PM2 PP5_Very_Strong

The NM_000249.4(MLH1):​c.453+1G>A variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: MLH1 NM_000249.4 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• 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]

MLH1 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.031704094 fraction of the gene. Cryptic splice site detected, with MaxEntScore 4.5, offset of 9, new splice context is: atgGTacat. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 3-37007064-G-A is Pathogenic according to our data. Variant chr3-37007064-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1319487.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MLH1	NM_000249.4	c.453+1G>A		splice_donor_variant, intron_variant		ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.453+1G>A		splice_donor_variant, intron_variant		1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Colorectal cancer, hereditary nonpolyposis, type 2 Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Department of Medical and Surgical Sciences, University of Bologna	Dec 06, 2024	The variant satisfied PS4, PVS1 and PM2 criteria. We performed transcript analysis which demonstrated its impact on splicing, allowing to add the PS3 criterion and to classify it as Pathogenic -
Pathogenic, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Jul 13, 2023	This variant is considered pathogenic. This variant occurs within a consensus splice junction and is predicted to result in abnormal mRNA splicing of either an out-of-frame exon or an in-frame exon necessary for protein stability and/or normal function. This variant is strongly associated with more severe personal and family histories of cancer, typical for individuals with pathogenic variants in this gene [PMID: 27363726]. -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Institute for Clinical Genetics, University Hospital TU Dresden, University Hospital TU Dresden

Nov 03, 2021

- -

Hereditary nonpolyposis colorectal neoplasms Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 21, 2022

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. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 1319487). Disruption of this splice site has been observed in individual(s) with clinical features of Lynch syndrome (PMID: 18931482, 23747338, 24278394, 26681312). This variant is not present in population databases (gnomAD no frequency). This sequence change affects a donor splice site in intron 5 of the MLH1 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in MLH1 are known to be pathogenic (PMID: 15713769, 24362816). -

Hereditary cancer-predisposing syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

May 10, 2024

The c.453+1G>A intronic variant results from a G to A substitution one nucleotide after coding exon 5 of the MLH1 gene. This variant has been identified in a proband who met Amsterdam I/II criteria for Lynch syndrome and tumor demonstrated loss of MLH1 and PMS2 expression by immunohistochemistry (De Lellis L et al. PLoS ONE, 2013 Nov;8:e81194) and an additional patient whose Lynch syndrome-associated tumor demonstrated loss of MLH1 and PMS2 expression by immunohistochemistry (de Voer RM et al. Gastroenterology, 2013 Sep;145:544-7). Additionally, this alteration was detected in 1/10030 consecutive patients referred for evaluation by an NGS hereditary cancer panel (Susswein LR et al. Genet Med, 2016 Aug;18:823-32). This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice donor site and may result in the creation or strengthening of a novel splice donor site. RNA studies have demonstrated that this alteration results in a transcript predicted to lead to a protein with an in-frame insertion of 3 amino acids; however, the exact functional impact of the inserted amino acids is unknown at this time (Ambry internal data). 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 likely pathogenic. This alteration was detected in X/132 unrelated individuals who met either Amsterdam I or Amsterdam II criteria. (De Lellis L et al. PLoS One, 2013 Nov;8:e81194). This alteration was identified in 1/10030 consecutive patients referred for evaluation by an NGS hereditary cancer panel (Susswein LR et al. Genet Med, 2016 Aug;18:823-32). (de Voer RM et al. Gastroenterology, 2013 Sep;145:544-7). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.44
CADD	Pathogenic	35
DANN	Uncertain	0.99
Eigen	Pathogenic	1.3
Eigen_PC	Pathogenic	1.2
FATHMM_MKL	Pathogenic	1.0	D
GERP RS		6.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.8

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.37		Position offset: 8
DS_DL_spliceai		1.0		Position offset: -1

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr3-37048555;