3-36993661-C-A

Variant names:

• chr3-36993661-C-A
• rs267607706
• NM_000249.4:c.114C>A

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000249.4(MLH1):​c.114C>A​(p.Asn38Lys) variant causes a missense, splice region change involving the alteration of a non-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 predict no significant impact on normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Pathogenic in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N38T) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: MLH1 NM_000249.4 missense, splice_region
• Scores: Splicing: ADA: 0.02985
• Clinical Significance: Likely pathogenic reviewed by expert panel P:2
• Conservation: PhyloP100: 2.48
• Publications: 7 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 18 ACMG points.

• PM1: In a hotspot region, there are 22 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 50 uncertain in NM_000249.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr3-36993660-A-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 619503.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.995
• PP5: Variant 3-36993661-C-A is Pathogenic according to our data. Variant chr3-36993661-C-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 561169.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.114C>A	p.Asn38Lys	missense_variant, splice_region_variant	Exon 1 of 19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.114C>A	p.Asn38Lys	missense_variant, splice_region_variant	Exon 1 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: reviewed by expert panel

Submissions by phenotype

Lynch syndrome 1 Pathogenic:1

Jun 13, 2018

International Society for Gastrointestinal Hereditary Tumours (InSiGHT)

Significance: Likely pathogenic

Review Status: reviewed by expert panel

Collection Method: curation

Same amino acid change as pathogenic variant -

Hereditary nonpolyposis colorectal neoplasms Pathogenic:1

Feb 23, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense change has been observed in individual(s) with colon cancer (PMID: 18415027). 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. This variant disrupts the p.Asn38 amino acid residue in MLH1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 12373605, 20020535, 20704743, 22290698, 22949379, 23403630). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. Experimental studies have shown that this missense change affects MLH1 function (PMID: 20020535). Based on a multifactorial likelihood algorithm using genetic, in silico, and/or statistical data, this variant has been determined to have a high probability of being pathogenic (PMID: 24362816). ClinVar contains an entry for this variant (Variation ID: 561169). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces asparagine, which is neutral and polar, with lysine, which is basic and polar, at codon 38 of the MLH1 protein (p.Asn38Lys). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.30
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	D
Eigen	Pathogenic	0.83
Eigen_PC	Pathogenic	0.67
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Pathogenic	0.84	D
MetaRNN	Pathogenic	1.0	D
MetaSVM	Uncertain	0.62	D
MutationAssessor	Pathogenic	5.0	H
PhyloP100		2.5
PrimateAI	Pathogenic	0.82	D
PROVEAN	Pathogenic	-4.8	D
REVEL	Pathogenic	0.89
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.98
MutPred		0.97		Gain of methylation at N38 (P = 0.0088);
MVP		0.97
MPC		0.43
ClinPred		1.0	D
GERP RS		4.2
PromoterAI		0.0094	Neutral
Varity_R		0.97
gMVP		0.96
Mutation Taster		=8/92	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.030
dbscSNV1_RF	Benign	0.31
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs267607706; hg19: chr3-37035152;