MLH1 Promoter Hypermethylation
General Information
Lab Name
MLH1 Promoter Hypermethylation
Lab Code
MLH1MT
Epic Name
Order using "UW Genetics and Solid Tumor Test Request"
See tip sheet for more information (internal link).
Description
MLH1 promoter methylation assay is useful for the evaluation of hereditary colorectal cancer and tumors that have MLH1 and PMS2 loss by immunohistochemistry (IHC). Approximately 85% of tumors that have IHC loss of MLH1 and PMS2 will have MLH1 promoter methylation, the majority of which is somatic in origin. The remaining tumors with IHC loss of MLH1 and PMS2 will have somatic or germline mutations in MLH1. Individuals with germline mutations in MLH1 have an increased risk for cancer associated with Lynch syndrome. When methylation is negative, molecular MLH1 testing of germline and/or tumor is recommended to determine the cause of the MLH1 and PMS2 loss and whether a patient has Lynch syndrome.
Synonyms
Colorectal cancer, endometrial cancer, Gynecological Oncology Pathway, GYNPTH
Components
| Code | Name |
|---|---|
| M1MTCH | MLH1 Methylation Clinical History |
| M1MTRE | MLH1 Methylation Result |
| M1MTIN | MLH1 Methylation Interpretation |
| M1MTMT | MLH1 Methylation Method |
| M1MTDI | MLH1 Methylation Director |
Interpretation
Method
Tumor DNA is bisulfite converted and amplified with a PCR-based assay to assess MLH1 promoter hypermethylation
Reference Range
See individual components
Guidelines
Ordering & Collection
Specimen Type
Collection
EITHER (a) slides OR (b) tissue block OR (c) blood:
(a) Instructions for slide specimens: 1 slide at 4-micron thickness stained with hematoxylin-and-eosin AND 10 unstained, non-baked slides at 10-micron thickness (a minimum of 5 unstained slides is acceptable). Unstained slides can be on charged or uncharged slides.
Note: sections should contain as much tumor as possible.
(b) Instructions for tissue block specimen: Provide complete tissue block containing tumor tissue. If there is more than one tissue block, please provide the block that has the greatest amount of tumor tissue. Tissue block will be returned at completion of testing.
(c) Instruction for blood specimens: Normal tissue or blood can be submitted for evaluation of constitutional MLH1 promoter hypermethylation
• 10 mL whole blood in LAVENDER TOP EDTA tube.
• Also acceptable: YELLOW TOP ACD tube, purified DNA from peripheral blood or cultured cells
(d) Add-on after prior testing in our lab: contact Genetics lab
Unacceptable: Decalcified sample
Forms & Requisitions
Providers with access to the UW implementation of Epic (i.e., FHCC, HMC, SCCA, UWMC, UWNW) may order this test using the order "UW Genetics and Solid Tumor Test Request." See tip sheet for more information (internal link).
Handling Instructions
Attach a copy of the pathology report for the tumor sample being submitted.
Outside Laboratories: Ship at room temperature.
Quantity
requested: Slides or tissue block or blood as noted above.
minimum: 5 unstained slides (10-micron thickness) with 20% tumor nuclei or 5mL peripheral blood
Processing
Hold slides or tissue blocks at room temperature.
Outside Laboratories: Ship at room temperature.
Performance
LIS Dept Code
Genetics (GEN)
Performing Location(s)
| UW-MT |
Genetics
Attention: Genetics Lab Tel: 206-598–6429 M–F (7:30 AM–4:00 PM) Tel (EXOME only): 206-543-0459 |
Manager Variant Review Scientist Faculty |
|---|
Frequency
Run at least once a week
Available STAT?
No