3-36996714-G-C

Position:

• chr3-36996714-G-C

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM2 PP3 PP5_Very_Strong

The NM_000249.4(MLH1):​c.207+5G>C variant causes a splice donor 5th base, intron change involving the alteration of a 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 (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: MLH1 NM_000249.4 splice_donor_5th_base, intron
• Scores: Splicing: ADA: 0.9872
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 9.39

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 11 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 3-36996714-G-C is Pathogenic according to our data. Variant chr3-36996714-G-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 141132.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.207+5G>C		splice_donor_5th_base_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.207+5G>C		splice_donor_5th_base_variant, intron_variant		1	NM_000249.4	ENSP00000231790	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Ambry Genetics	Feb 26, 2019	The c.207+5G>C intronic variant results from a G to C substitution 5 nucleotides after coding exon 2 in the MLH1 gene. This alteration has been reported in an individual whose family history met Amsterdam criteria and who had an HNPCC-related tumor that was MLH1/PMS2-absent and microsatellite unstable (Pearlman R et al. JAMA Oncol. 2017;3(4):464-471). Analysis of patient-derived RNA found that this alteration results in aberrant splicing leading to transcripts lacking coding exon 2 (Pearlman R et al. JAMA Oncol. 2017;3(4):464-471). In addition, this alteration co-segregates with HNPCC-related tumors in multiple families (Pearlman R et al. JAMA Oncol. 2017;3(4):464-471; Ambry internal data). Based on the majority of available evidence to date, this variant is likely to be pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Dec 01, 2020	This variant causes a G to C nucleotide substitution at the +5 position of intron 2 of the MLH1 gene. A functional RNA study has shown that this variant causes out-of-frame skipping of exon 2, resulting in premature truncation (PMID: 27978560). This variant has been reported in two individuals affected with colorectal cancer that exhibited DNA mismatch repair deficient tumor pathology (PMID: 27978560, 32620519) and to cosegregate with disease in a family with multiple individuals affected with colorectal cancer (PMID: 27978560). This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Loss of MLH1 function is a known mechanism of disease (clinicalgenome.org). Based on the available evidence, this variant is classified as Likely Pathogenic. -

Lynch syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing;in vitro

University of Washington Department of Laboratory Medicine, University of Washington

Mar 25, 2016

RNA evidence indicating exon 2 skipping and familial co-segregation analysis indicated evidence for cosegregation of this variant with colon cancers that have loss of MLH1 on IHC (likelihood ratio 25.28, LOD: 1.4). Taken together this is sufficient evidence for variant pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.23
CADD	Uncertain	25
DANN	Uncertain	0.98
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.99
dbscSNV1_RF	Pathogenic	0.88
SpliceAI score (max)		0.87		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.87		Position offset: -5

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

Publications

LitVar

Other links and lift over

dbSNP: rs587781518; hg19: chr3-37038205;