MLH1

mutL homolog 1

12 disorders 6 untyped 3 causative 2 no genetic record 1 risk factor 3p22.2 gene with protein product

HGNC:7127 Monarch NCBI Gene 4292 ENSG00000076242 UniProt P40692 OMIM 120436

Previous symbols: COCA2. Aliases: HNPCC, FCC2, HNPCC2, MLH-1.

In the knowledge base · computed from kb/ at build time

Disorders

Relationship is the entry's genetic[].relationship_type. untyped means the entry has a genetic record for the gene but does not type it; its free-text association is shown instead.

Disorder	Relationship	Where the gene appears
Constitutional Mismatch Repair Deficiency	causative germline loss of function	mechanism: Biallelic Germline Mismatch Repair Gene Inactivation subtype: CMMRD1 scoped to subtype: CMMRD1
Gastric Adenocarcinoma	causative	mechanism: Mismatch Repair Deficiency and Microsatellite Instability biochemical: Mismatch Repair / Microsatellite Instability Status scoped to subtype: MSI
Lynch Syndrome	causative germline loss of function	mechanism: DNA Mismatch Repair Deficiency subtype: MLH1 Mutation
Small Intestine Cancer	risk factor
BRAF V600E-Mutant Colorectal Cancer	untyped Promoter Hypermethylation in MSI-H Subtype	mechanism: MLH1 Silencing and MSI-H Branch
Endometrial Carcinoma	untyped Promoter hypermethylation or mismatch repair deficiency
Huntington Disease	untyped Genetic Modifier
MSI-High Colorectal Cancer	untyped Loss of Function (Somatic or Germline)
MSI-High Endometrial Cancer	untyped Germline or Promoter Hypermethylation
Pancreatic Ductal Adenocarcinoma	untyped Inherited susceptibility
Endometrial Endometrioid Adenocarcinoma	no genetic record	mechanism: Mismatch Repair Deficiency
Ovarian Endometrioid Carcinoma	no genetic record	mechanism: Mismatch Repair Deficiency

ClinGen gene–disease validity · snapshot 2026-10-03 · matched to entries by MONDO

An entry matches when ClinGen's MONDO disease is the entry's own disease term, a subtype term, or an exact-match mapping. An amber status marks an entry ClinGen supports the gene for (Definitive, Strong or Moderate) whose own record does not type it. A Limited, Disputed or Refuted tier on such an entry is not a gap.

ClinGen disease	MOI	Classification	dismech entry
Lynch syndrome MONDO:0005835	AD	Definitive 2022-06-20	Lynch Syndrome causative
mismatch repair cancer syndrome 1 MONDO:0010159	AR	Definitive 2018-10-09	Constitutional Mismatch Repair Deficiency causative
hereditary breast carcinoma MONDO:0016419	AD	Refuted 2023-12-21	no dismech entry

Mechanism modules · computed from kb/

genome_instability_mutation via Constitutional Mismatch Repair Deficiency, Gastric Adenocarcinoma, Lynch Syndrome
mismatch_repair_driven_repeat_instability named in the module itself

Identity from HGNC (snapshot 2026-10-01). Page layers are described in the gene pages documentation.