MGMT (O6-Methylguanine-DNA Methyltransferase) Gene Methylation Assay

TEST: 489280
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CPT: 81287; 88381
Updated on 12/13/2024
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Synonyms

  • O6-Methylguanine-DNA Methyltransferase (MGMT)

Special Instructions

Please provide a copy of the pathology report. Sample submission without a copy of the pathology report may delay testing. Please direct any questions regarding this test to customer service at 800-345-4363.

Expected Turnaround Time

7 - 10 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Documents

For more information, please view the literature below.

MGMT Gene Methylation Assay: A Biomarker for Therapy Consideration in Glioblastoma

    Specimen Requirements

    Specimen

    Glioblastoma specimens in formalin-fixed, paraffin-embedded (FFPE) tissue blocks or slides

    Formalin-fixed, paraffin-embedded (FFPE) tissue blocks or slides.

    Glioblastoma specimens in formalin-fixed, paraffin-embedded (FFPE) tissue blocks or slides

    Volume

    FFPE tissue block or eight unstained slides at 5 μM and one matching H&E slide or nine precut unstained slides from a paraffin block in 5-μM sections

    Minimum Volume

    50mm2 total tumor area is required for testing. Two unstained slides at 5 μM and one matching H&E slide or three unstained slides at 5 μM.

    Collection

    FFPE tissue block or eight unstained slides at 5 μM and one matching H&E slide or nine precut unstained slides from a paraffin block in 5-μM sections

    Storage Instructions

    Maintain blocks/slides at room temperature.

    Causes for Rejection

    Tissue is not primary brain tumor; tumor block containing insufficient tumor tissue; tumor fixed in a heavy metal fixative; broken or stained slides; decalcified specimens

    Test Details

    Use

    MGMT (O6-methylguanine-DNA methyltransferase) is a DNA repair enzyme that is involved in the repair of damage caused by a variety DNA cross-linking compounds, including alkylating agents. Increased methylation of the MGMT gene promoter region causes diminished or silenced expression of the gene, making cells more sensitive to DNA damage. The relationship has been shown for glioblastomas and alkylating agents such as temozolomide (Temodar®).

    Limitations

    Preparation of DNA from tissue samples is dependent upon the quality of the provided specimen. Inadequate DNA extraction may occur in a significant number of paraffin-embedded samples.

    Methodology

    Quantitative methylation-specific polymerase chain reaction (PCR)

    Additional Information

    Approximately 40% to 50% of glioblastoma multiforme (GBM) tumors exhibit MGMT gene methylation. Retrospective studies have shown that detection of MGMT promoter methylation in tumor samples is associated with an increased likelihood of a favorable response to temozolomide.

    References

    Brandes AA, Franceschi E, Tosoni A, et al. MGMT promoter methylation status can predict the incidence and outcome of pseudoprogression after concomitant radiochemotherapy in newly diagnosed glioblastoma patients. J Clin Oncol. 2008 May 1; 26(13):2192-2197.18445844
    Hau P, Stupp R, Hegi ME. MGMT methylation status: The advent of stratified therapy in glioblastoma? Dis Markers. 2007; 23(1-2):97-104.17325429
    Hegi ME, Diserens AC, Gorlia T, et al. MGMT gene silencing and benefit from temozolomide in glioblastoma. N Engl J Med. 2005 Mar 10; 352(10):997-1003.15758010
    Vlassenbroeck I, Califice S, Diserens AC, et al. Validation of real-time methylation-specific PCR to determine O6-methylguanine-DNA methyltransferase gene promoter methylation in glioma. J Mol Diagn. 2008 Jul; 10(4):332-337.18556773

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