Home
HelpTest Code MLHPB MLH1 Hypermethylation Analysis, Blood
Useful For
As an adjunct to positive hypermethylation in tumor to distinguish between somatic and germline hypermethylation
As an adjunct to negative MLH1 germline testing in cases where colon or endometrial tumor demonstrates microsatellite instability-H (MSI-H) and loss of MLH1 protein expression
Disease States
- Lynch syndrome
Special Instructions
Method Name
Polymerase Chain Reaction (PCR)
Reporting Name
MLH1 Hypermethylation Analys, BloodSpecimen Type
VariesShipping Instructions
Specimen Required
Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.
Submit only 1 of the following specimens:
Specimen Type: Whole blood
Container/Tube: Lavender top (EDTA) or yellow top (ACD)
Specimen Volume: 3 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send whole blood specimen in original tube. Do not aliquot.
Specimen Stability Information: Ambient (preferred) 4 days/Refrigerated 4 days/Frozen 4 days
Additional Information:
1. Specimens are preferred to be received within 4 days of collection. Extraction will be attempted for specimens received after 4 days, and DNA yield will be evaluated to determine if testing may proceed.
2. To ensure minimum volume and concentration of DNA is met, the requested volume must be submitted. Testing may be canceled if DNA requirements are inadequate.
Specimen Type: Cord blood
Container/Tube:
Preferred: Lavender top (EDTA) or yellow top (ACD)
Specimen Volume: 3 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send cord blood specimen in original tube. Do not aliquot.
Specimen Stability Information: Ambient (preferred) 4 days/Refrigerated 4 days/Frozen 4 days
Additional Information:
1. Specimens are preferred to be received within 4 days of collection. Extraction will be attempted for specimens received after 4 days, and DNA yield will be evaluated to determine if testing may proceed.
2. To ensure minimum volume and concentration of DNA is met, the requested volume must be submitted. Testing may be canceled if DNA requirements are inadequate.
3. While a properly collected cord blood sample may not be at risk for maternal cell contamination, unanticipated complications may occur during collection. Therefore, maternal cell contamination studies are recommended to ensure the test results reflect that of the patient tested and are available at an additional charge. Order MATCC / Maternal Cell Contamination, Molecular Analysis, Varies on the maternal specimen.
Specimen Type: Extracted DNA
Container/Tube:
Preferred: Screw Cap Micro Tube, 2 mL with skirted conical base
Acceptable: Matrix tube, 1 mL
Collection Instructions:
1. The preferred volume is at least 100 mcL at a concentration of 75 ng/mcL.
2. Include concentration and volume on tube.
Specimen Stability Information: Frozen (preferred) 1 year/Ambient/Refrigerated
Additional Information: DNA must be extracted in a CLIA-certified laboratory or equivalent and must be extracted from a specimen type listed as acceptable for this test (including applicable anticoagulants). Our laboratory has experience with Chemagic, Puregene, Autopure, MagnaPure, and EZ1 extraction platforms and cannot guarantee that all extraction methods are compatible with this test. If testing fails, one repeat will be attempted, and if unsuccessful, the test will be reported as failed and a charge will be applied. If applicable, specific gene regions that were unable to be interrogated due to DNA quality will be noted in the report.
Specimen Minimum Volume
See Specimen Requirements
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Varies | |
Reject Due To
All specimens will be evaluated by Mayo Clinic Laboratories for test suitability.Clinical Information
The lifetime risk of colorectal cancer in the general population is 4% to 6%.(1) Lynch syndrome (also known as hereditary nonpolyposis colorectal cancer) is an autosomal dominant hereditary cancer syndrome accounting for 2% to 4% of all colorectal cancer cases.(2,3)
Lynch syndrome is associated with germline variants in the mismatch repair (MMR) genes, MLH1, MSH2, MSH6, and PMS2, or deletions of the EPCAM gene. It is predominantly characterized by significantly increased risks for colorectal and endometrial cancer.(2,3) The lifetime risk for cancer is highly variable and dependent on the gene involved. Other malignancies within the tumor spectrum include gastric, ovarian, and small bowel cancers and hepatobiliary and upper urinary tract carcinomas.(2,3)
Several laboratory-based strategies may be utilized to screen for Lynch syndrome, including testing tumor tissue for the presence of microsatellite instability (MSI-H) and assessment of protein expression of MMR proteins (MLH1, MSH2, MSH6, PMS2) by immunohistochemistry (IHC).
Defective MMR in sporadic colon cancer is most often due to molecular variation in MLH1, of which promoter hypermethylation (epigenetic silencing) constitutes the most common cause of MLH1 inactivation. A somatic-occurring variant in the BRAF gene (V600E) is present in approximately 70% of tumors with hypermethylation of the MLH1 promoter. Importantly, the V600E variant is rarely identified in cases with disease-causing germline MLH1 variants.
While most MLH1 promoter hypermethylation occurs sporadically, some individuals with tumor hypermethylation may have germline inactivation of the MLH1 gene via constitutional promoter hypermethylation. This condition is known as constitutional MLH1 promoter hypermethylation, which is consistent with a diagnosis of Lynch syndrome.(4-7) In contrast to sequence variants in MLH1, current evidence suggests that the risk of transmitting constitutional MLH1 promoter hypermethylation is less than50%. As such, these individuals may not have a strong family history of Lynch-related cancers and often test negative on traditional germline sequencing panels. Thus, testing for constitutional MLH1 promoter hypermethylation may be considered if there is still suspicion for an inherited etiology following negative germline testing for patients with MLH1 promoter methylated tumors.
For more information see Lynch Syndrome Testing Algorithm
Reference Values
Interpretive report will be provided.
Interpretation
The report will include specimen information, assay information, and interpretation of test results.
Absence of hypermethylation is reported as not providing evidence for germline (constitutional) MLH1 promoter hypermethylation. Presence of hypermethylation is reported as consistent with germline (constitutional) inactivation of MLH1 by promoter hypermethylation.
Day(s) Performed
Varies
Report Available
8 to 12 daysSpecimen Retention Time
Whole blood: 30 days (if available); Extracted DNA: 3 monthsPerforming 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. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
81288
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| MLHPB | MLH1 Hypermethylation Analys, Blood | 97760-3 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 52906 | Result Summary | 50397-9 |
| 52907 | Result | 82939-0 |
| 52908 | Interpretation | 69047-9 |
| 52909 | Reason for Referral | 42349-1 |
| 52910 | Specimen | 31208-2 |
| 52911 | Source | 31208-2 |
| 52912 | Released By | 18771-6 |
Forms
1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file.
-Informed Consent for Genetic Testing (T576)
-Informed Consent for Genetic Testing-Spanish (T576)
2. Molecular Genetics: Inherited Cancer Syndromes Patient Information (T519)
3. If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.
Testing Algorithm
For information see Lynch Syndrome Testing Algorithm.