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MGMT Promoter Methylation Assay
|Utilization Guidelines||Tests with long turn-around times (ie. Molecular based tests and Microarrays) should only be requested on an inpatient if the result is going to affect the inpatient management.
If the patient will likely be discharged before the result will be available, the test should be requested after discharge. (NOTE: UCSF Medical Center is not reimbursed for inpatient testing).
An exception to the above may be appropriate if there is a possibility the patient will not survive to be discharged and the information is important for diagnosis and/or family decisions/management (ie. recurrence risk).
|Performed by||Medical Genomics - Molecular Diagnostics|
|In House Availability||Run 1x per week, day shift only|
|Method||Bisulfite treatment, PCR and DNA sequencing|
|Collection Instructions||Sections on slides selected for MGMT methylation analysis must be at least 1 cm and consists of at least 50% tumor.
A pathologist must circle the tumor area of an H&E slide. Five (5) unstained additional slides cut serially adjacent after the H&E slide must also be submitted.
Label slides with pathology case number and block identification.
All specimens not ordered directly by UCSF Pathology must be accompanied with a completed Molecular Diagnostics Requisition form and a pathology report.
For UCSF Samples (from remote sites) Click here for sample collection instructions
For NON-UCSF Samples Click here for Requisition form & Account set-up instructions.
Note we only do institutional billing.
|Sample type||Formalin-fixed, paraffin-embedded 10-micron tissue sections on five (5) unstained, uncharged glass slides. One adjacent H&E stained slide should be included.|
|UCSF Rejection Criteria||Insufficient tumor tissue present on slide as determined by pathologist and/or lab.
All required slides not included.
Slides not labeled or not accompanied by completed requisition form (if not ordered directly through Department of Pathology).
|Synonyms||O6 methylguanine DNA methyltransferase|
|Stability||Formalin-fixed, paraffin-embedded tissues are stable indefinitely at room temperature|
|Turn around times||2-3 weeks|
|Additional information||An interpretation of this test by a laboratory physician will automatically be performed and billed for separately.
The addition of a methyl group to the O6 position of guanine is a mutagenic event that is corrected by a DNA repair protein encoded by the MGMT gene. If the MGMT repair mechanism fails to occur, cells will undergo apoptosis and thus become more susceptible to drug induced-cytotoxicity. In some glioblastoma tumors, epigenetic methylation at the MGMT promoter, results in silencing of MGMT RNA and protein expression, culminating in the loss of DNA repair at the O6 methyl guanine.
The coupling of MGMT promoter methylation with radiotherapy and alkylating chemotherapy drugs such as carmustine or temozolomide, has been shown to increase mean patient survival. Therefore, this test is used as a prognostic indicator to treatment with alkylating agents.
The assay is based on bisulfite treated DNA recovered from the tumor areas of the submitted slides. DNA sequencing of 17 CpG dinucleotides in a region of the MGMT promoter that contains Sp1 transcription factor binding sites, will determine the extent of methylation status of CpG dinucleotides.
The result is reported as "POSITIVE: METHYLATED" if one or more CpG sites are methylated. A methylation index ranging from 0-17 is reported to reflect the extent of MGMT promoter methylation of this region.
This test was developed and its performance characteristics determined by the Clinical Laboratories at the Medical Center at UC San Francisco. It has not been cleared or approved by the U.S. Food and Drug Administration.
|LDT or Mod FDA?||Yes|
|Last Updated||3/13/2014 9:44:47 AM|