NM_000249.4:c.655A>C

Variant names:

• chr3-37012077-A-C
• rs1799977
• NM_000249.4:c.655A>C
• MLH1 p.Ile219Leu

GermlineCancer (beta)

Variant summary

Our verdict is Uncertain significance.

+2 Uncertain · Warm

-7

-6

-1

0

+5

+6

+9

+10

BenignB

Likely BenignLB

UncertainVUS

Likely PathogenicLP

PathogenicP

The variant received 2 classification points (ACGS-UK Somatic Oncogenicity v2025). O3_Moderate

The NM_000249.4(MLH1):c.655A>C (p.Ile219Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The gene MLH1 is a tumor suppressor gene (CancerMine: 10 TSG, 4 oncogene, 3 driver citations). The gene MLH1 is a known oncogene (CancerMine: 10 TSG, 4 oncogene, 3 driver citations). The gene MLH1 is a cancer driver gene (CancerMine: 10 TSG, 4 oncogene, 3 driver citations). The variant is absent from the gnomAD population database at sites with sufficient sequencing coverage. Splicing prediction tools (SpliceAI) predict no significant impact on normal splicing. Variant has been reported in ClinVar as Benign/Likely Benign (★★★). Other variants at the same amino acid position have been reported in ClinVar (not pathogenic): p.I219M: Uncertain_significance (ClinVar VariationId 489902, 1 star); p.I219T: Uncertain_significance (ClinVar VariationId 483584, 2 stars); p.I219V: Conflicting_classifications_of_pathogenicity (ClinVar VariationId 920597); p.I219V: Benign (ClinVar VariationId 36557, 3 stars)

• Frequency: Genomes: not found (cov: 32)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Benign reviewed by expert panel B:1
• Conservation: PhyloP100: 2.05
• Publications: 124 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: ClinGen, G2P, Orphanet
• Lynch syndrome 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Genomics England PanelApp, Ambry Genetics
• Muir-Torre syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Genomics England PanelApp, G2P, Ambry Genetics
• mismatch repair cancer syndrome 1

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, ClinGen, Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• 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

Classification according to ACGS-UK Somatic Oncogenicity v2025

Specifications for MLH1 are available in the ClinGen Criteria Specification Registry and recommended for reference when assigning criteria.

Classification was made for transcript:

Our verdict: Uncertain_significance. The variant received 2 points.

Apply	Criterion Code & Title / Strength	Strength	Rationale / Clinical Context
	O3Absent or very rare in population		Absent or extremely rare in gnomAD (AC ≤ 2) — O3 moderate; GnomAD: AF = absent, AC = 0 — absent/extremely rare (O3 moderate [+2])

Variant Effect in Transcripts

Automated classification analysis was done for transcript: NM_000249.4. You can select a different transcript below to see updated classification assignments.

RefSeq Transcripts

Sel.	Gene / Transcript	Tags	HGVSc / HGVSp	Effect	Exon rank	Protein / UniProt
	MLH1 NM_000249.4	MANE Select	c.655A>C p.Ile219Leu	missense	Exon 8 of 19	Prot: NP_000240.1 UniProt:
	MLH1 NM_001354628.2		c.655A>C p.Ile219Leu	missense	Exon 8 of 18	Prot: NP_001341557.1 UniProt:
	MLH1 NM_001354629.2		c.556A>C p.Ile186Leu	missense	Exon 7 of 18	Prot: NP_001341558.1 UniProt:

MLH1 NM_000249.4

MANE Select

HGVSc / HGVSpc.655A>Cp.Ile219Leu

Exon rankExon 8 of 19

missense

Prot: NP_000240.1UniProt: P40692-1

MLH1 NM_001354628.2

HGVSc / HGVSpc.655A>Cp.Ile219Leu

Exon rankExon 8 of 18

missense

Prot: NP_001341557.1UniProt: A0A087WX20

MLH1 NM_001354629.2

HGVSc / HGVSpc.556A>Cp.Ile186Leu

Exon rankExon 7 of 18

missense

Prot: NP_001341558.1UniProt: A0AAQ5BGZ2

Ensembl Transcripts

Sel.	Gene / Transcript	Tags	HGVSc / HGVSp	Effect	Exon rank	Protein / UniProt
	MLH1 ENST00000231790.8	TSL:1MANE Select	c.655A>C p.Ile219Leu	missense	Exon 8 of 19	Prot: ENSP00000231790.3 UniProt:
	MLH1 ENST00000456676.7	TSL:1	c.655A>C p.Ile219Leu	missense	Exon 8 of 17	Prot: ENSP00000416687.3 UniProt:
	MLH1 ENST00000413740.2	TSL:1	c.655A>C p.Ile219Leu	missense	Exon 8 of 15	Prot: ENSP00000416476.2 UniProt:

MLH1 ENST00000231790.8

TSL:1MANE Select

HGVSc / HGVSpc.655A>Cp.Ile219Leu

Exon rankExon 8 of 19

missense

Prot: ENSP00000231790.3UniProt: P40692-1

MLH1 ENST00000456676.7

TSL:1

HGVSc / HGVSpc.655A>Cp.Ile219Leu

Exon rankExon 8 of 17

missense

Prot: ENSP00000416687.3UniProt: H0Y818

MLH1 ENST00000413740.2

TSL:1

HGVSc / HGVSpc.655A>Cp.Ile219Leu

Exon rankExon 8 of 15

missense

Prot: ENSP00000416476.2UniProt: H0Y806

Frequencies

Allele frequencies (AF), counts (AC/AN), homozygotes and coverage

Common (AF > 0.05 / Hom > 5)

Rare (AF ≤ 0.0001 / Hom ≤ 1)

Source / population	AF	AC	Hom	AN	Coverage
Global population databases 3 sources Large-scale international reference populations
GnomAD3 genomes	AF:	AC:	Hom:	AN:	Cov:32
GnomAD4 exome	AF:	AC:	Hom:	AN:	Cov:32
GnomAD4 genome	AF:	AC:	Hom:	AN:	Cov:32

Showing 3 sources

ClinVar

ClinVar submissions

Significance: Benign

Revision: reviewed by expert panel

Pathogenic	VUS	Benign	Condition
-	-	1	Lynch syndrome (1)

Computational Scores

Algorithm	Calibrated pred.	Score	Prediction
AlphaGenome AVI	Uncertain	17
AlphaMissense	Benign	0.12
BayesDel_addAF	Uncertain	0.13	D
BayesDel_noAF	Uncertain	-0.060
CADD	Benign	19
DANN	Uncertain	0.98
DEOGEN2	Uncertain	0.51	D
Eigen	Benign	-0.046
Eigen_PC	Benign	0.12
FATHMM_MKL	Uncertain	0.94	D
FuncVEP CTI	Benign	0.0053
GPN-Star LLR	N/A	-7.0
GPN-Star score	N/A	7.0
LIST_S2	Uncertain	0.95	D
M_CAP	Benign	0.066	D
MetaRNN	Benign	0.31	T
MetaSVM	Benign	-0.41	T
Mutation Taster	N/A	63/37	polymorphism
MutationAssessor	Benign	1.4	L
PhyloP100	Benign	2.0
popEVE	Benign	-3.2
PrimateAI	Uncertain	0.50	T
PROVEAN	Benign	-0.95	N
RBP_binding_hub_radar	N/A	0.0
RBP_regulation_power_radar	N/A	1.7
REVEL	Uncertain	0.50
Sift	Benign	0.32	T
Sift4G	Benign	0.52	T
Varity_R	N/A	0.24
VESM-3B	Benign	-7.9

Showing 30 of 30 scores

Splicing Scores

Algorithm	Calibrated pred.	Score	Prediction
Pangolin (max)	Benign	0.020
SpliceAI score (max)	Benign	0.010	Details are displayed if max score is > 0.2

Showing 2 of 2 scores

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

MaveDB functional evidence

MaveDB is a public repository of laboratory assays that test the effect of thousands of variants at once — treat this as supporting research data and interpret it with great caution; it is not a clinical classification.

No MaveDB functional evidence found for this variant.

Other links and lift over

dbSNP: rs1799977;

hg19: chr3-37053568;

ACMG debug oncogenicity

ACGS debug oncogenicity

ACMG debug germline

Submit to ClinVar