Laboratory Lab results are too important to go anywhere else.

MLH 1 Promoter Methylation Status

MLH 1 promoter methylation, MSI, microsatellite instability, mismatch repair, MMR, sporadic MSI/MMR, Lynch Syndrome, colon cancer

Test Codes

SOFTPATH: MLHIG, SOFTMOL: MLHI, SOFTLAB: MLHIG

Department

Molecular Pathology

Specimen Collection Criteria

Collect: Paraffin-embedded tissue. A paraffin block must be submitted. (Slides or paraffin shavings are not acceptable.) Submit formalin-fixed, paraffin-embedded block with corresponding H&E slide. Tissue should be well fixed and well processed. Average tissue size 5.0 mm².

• DNA will be assessed for quality. If it is deemed unacceptable, testing will be cancelled with client notification.
• The specimen must be accompanied by a completed requisition and must contain the patient name, date of birth, collection date, ordering physician, and source of specimen. 

Physician Office/Draw Specimen Preparation

Maintain paraffin-embedded tissue at room temperature (20-26°C or 68-78.8°F) until transport.

Preparation for Courier Transport

Transport: Paraffin-embedded tissue, at room temperature (20-26°C or 68-78.8°F).

Rejection Criteria

• Decalcified tissue.
• Fixatives other than 10% neutral buffered formalin.
• Specimens fixed/processed in alternative fixatives (e.g. alcohol, zinc formalin).
• Improper labeling or inadequate information. 
• Less than 10 percent tumor cellularity, at discretion of medical director.
• Poor quality and/or quantity of extracted genomic DNA.

Testing will be cancelled on specimens meeting the above criteria with client notification.

Inpatient Specimen Preparation

Specimens at Royal Oak may be sent to the Surgical Pathology tube station, #201. In-house specimens are also picked up by a Surgical Pathology assistant every hour on the hour.

In-Lab Processing

Maintain specimens at room temperature (20-26°C or 68-78.8°F) until testing.

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): Indefinitely
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Room Temperature (20-26°C or 68-78.8°F): 7 days

Specimen Storage (DNA libraries post testing):

Frozen (-25 to -15°C): 2 months

Laboratory

Royal Oak Clinical Molecular Pathology Laboratory

Performed

Monday – Friday.
Results available in 7-10 business days.

Reference Range

MLH-1 promoter is not methylated.

Test Methodology

Following DNA extraction and bisulfate treatment, molecular analysis of the promoter region of the MLH-1 gene is performed by methylation-specific Real-Time PCR using an ABI 7500 FAST Real-Time PCR Instrument (Applied Biosystems Inc, Foster City, CA).

Interpretation

MLH-1 promoter is not methylated.
MLH-1 promoter is methylated.

Clinical Utility

For colorectal cancers that demonstrate microsatellite instability, methylation of the MLH-1 gene promoter is consistent with sporadic MSI, rather than germline (i.e. Lynch Syndrome) MSI.

Reference

1. Hegi ME, Lie L, Herman JG, Stupp R, Wick W, Weller M, Mehta MP, Gilbert MR. Correlation of O⁶-Methylguanine Methyltransferase (MGMT) Promoter Methylation with Clinical Outcomes in Glioblastoma and Clinical Strategies to Modulate MGMT Activity. JClin Oncol. 2008 Sep 1;26(25):4189-99.
2. Karayan-Tapon L, Quillien V, Guilhot J, Wager M, Fromont G, Saikali S, Etcheverry A, Hamlat A, Loussouarn D, Campion L, Campone M, Vallette FM, Gratas-Rabbia-Re C. Prognostic Value of O(6)-Methylguanine-DNA Methyltransferase Status in Glioblastoma Patients, Assessed by Five Different Methods. J Neurooncol. 2009 Oct 20.
3. Rivera AL, Pelloski CE, Gilbert MR, Colman H, De La Cruz C, Sulman EP, Bekele BN, Aldape KD. MGMT Promoter Methylation is Predictive of Response to Radiotherapy and Prognostic in the Absence of Adjuvant Alkylating Chemotherapy for Glioblastoma. Neuro Oncol. 2010 Feb; 12(2):116-21. Epub 2009 Dec 14. 

CPT Codes

81288

Contacts

Last Updated

3/22/2021