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Test Code ML1HM MLH1 Hypermethylation Analysis, Tumor

Ordering Guidance

This test is not recommended as a first-tier screening measure for hereditary nonpolyposis colon cancer. For more information see TMSI / Microsatellite Instability, Tumor and IHC / Mismatch Repair (MMR) Protein Immunohistochemistry Only, Tumor.


Testing will only be performed on colon or endometrial tumors demonstrating loss of MLH1 protein expression by immunohistochemistry.


Mayo Clinic's preferred screening test includes both MLH1 promoter hypermethylation and BRAF V600E testing. Order BRMLH / MLH1 Hypermethylation and BRAF Mutation Analysis, Tumor.


Extracted DNA from tissues is not an acceptable specimen type.

Necessary Information

Pathology report must accompany specimen in order for testing to be performed.

Specimen Required

Specimen Type: Tissue block or slide

Collection Instructions:

1. Submit formalin-fixed, paraffin-embedded tissue block (preferred) or 1 slide stained with hematoxylin and eosin and 10 unstained, nonbaked slides (5-micron thick sections) of the tumor tissue.

2. Sections should contain tumor tissue.


1. Molecular Genetics: Inherited Cancer Syndromes Patient Information (T519)

2. If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Gastroenterology and Hepatology Client Test Request (T728)

-Oncology Test Request (T729)

Useful For

An adjunct to TMSI / Microsatellite Instability, Tumor and IHC / Mismatch Repair (MMR) Protein Immunohistochemistry Only, Tumor when colon or endometrial tumor demonstrates microsatellite instability (MSI-H) and loss of MLH1 protein expression, to help distinguish a somatic versus germline event prior to performing expensive germline testing


An adjunct to negative MLH1 germline testing in cases where colon or endometrial tumor demonstrates MSI-H and loss of MLH1 protein expression

Additional Tests

Test ID Reporting Name Available Separately Always Performed
SLIRV Slide Review in MG No, (Bill Only) Yes

Testing Algorithm

When this test is ordered, slide review will always be performed at an additional charge.


For more information see Lynch Syndrome Testing Algorithm.

Method Name

Polymerase Chain Reaction (PCR)

Reporting Name

MLH1 Hypermethylation Analys, Tumor

Specimen Type


Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Ambient (preferred)

Reject Due To

Specimens that have been decalcified (all methods)
Specimens that have not been formalin-fixed, paraffin-embedded
Bone marrow in EDTA

Reference Values

An interpretative report will be provided.

Day(s) Performed


Report Available

7 to 14 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information



LOINC Code Information

Test ID Test Order Name Order LOINC Value
ML1HM MLH1 Hypermethylation Analys, Tumor 97761-1


Result ID Test Result Name Result LOINC Value
53299 Result Summary 50397-9
53300 Result 82939-0
53301 Interpretation 69047-9
53302 Reason for Referral 42349-1
53303 Specimen 31208-2
53304 Source 85298-8
54447 Tissue ID 80398-1
53305 Released By 18771-6

Secondary ID


Specimen Minimum Volume

See Specimen Required