What are other Names for this Test? (Equivalent Terms)
- O(6)-Methylguanine-DNA Methyltransferase Mutation Analysis Test
What is MGMT Mutation Analysis Test? (Background Information)
- MGMT mutation refers to an alteration in the MGMT gene, which may make an individual with a certain kind of brain cancer (glioma) more likely to respond well to chemotherapy
- The MGMT gene gives instructions for the MGMT protein. The MGMT protein repairs DNA damage, which normally makes it essential to the prevention of cancer and other genetic disorders
- However, individuals with brain cancer often undergo treatment called alkylating chemotherapy. This involves the use of chemotherapy drugs, such as temozolamide, that fight cancer by damaging its DNA
- Alterations in the MGMT gene may result in a defective MGMT protein that is unable to repair DNA damage. Normally, this is detrimental because it weakens an individual’s ability to prevent cancer and other disorders
- However, in individuals with glioma, the MGMT mutation is beneficial because the resulting inability to repair DNA means increased effectiveness of DNA-damaging alkylating therapy
- The MGMT Mutation Analysis Test is a genetic test that detects abnormalities in the MGMT gene. It is used to estimate the effectiveness of alkylating chemotherapy in individuals with glioma
The molecular testing, in general, can be performed using a variety of methods. Some of these methods include:
- In situ hybridization technique, such as fluorescence in situ hybridization (FISH)
- Immunohistochemistry (IHC)
- Next-generation sequencing (NGS)
- Polymerase chain reaction (PCR)
- Comparative genomic hybridization (CGH)
- Karyotyping including spectral karyotyping
- mRNA analysis
- Tissue microarrays (TMAs)
- Southern blot test
- Northern blot test
- Western blot test
- Eastern blot test
The methodology used for the test may vary from one laboratory to another.
Note: Molecular testing has limitations due to the molecular method and genetic mutational abnormalities being tested. This can affect the results on a case-by-case basis. Consultation with your healthcare provider will help in determining the right test and right molecular method, based on individual circumstances.
What are the Clinical Indications for performing the MGMT Mutation Analysis Test?
Following are the clinical indications for performing the MGMT Mutation Analysis Test:
- Estimating the prognosis of newly-diagnosed gliomas
- Determining the effectiveness of alkylating chemotherapy in treating glioma
- Guiding chemotherapy in individuals diagnosed with glioma, who are more than 60 years old
In general, the molecular genetic testing is undertaken in the following situations:
- To assist (and in some cases, confirm) the initial diagnosis
- To distinguish other tumors/conditions that have similar histological features, when examined by a pathologist under the microscope
- To help in determining treatment options
- To confirm recurrence of the tumor: Tumor recurrence can either be at the original tumor site, or at a distant location (away from the initial site)
How is the Specimen Collected for MGMT Mutation Analysis Test?
Following is the specimen collection process for MGMT Mutation Analysis Test:
The specimen sample requirements may vary from lab to lab. Hence, it is important to contact the testing lab for exact specimen requirements, before initiating the testing process.
- Sample on which the test is performed may include:
- Fresh tumor tissue during biopsy
- Formalin-fixed paraffin-embedded solid tumor tissue (FFPE tumor tissue), often referred to as paraffin block of the tumor
- Unstained tissue slides
- Process of obtaining the sample: As outlined by the laboratory testing facility
- Preparation required: As outlined by the laboratory testing facility
- In some cases, a different source of specimen (such as peripheral blood, bone marrow biopsy specimen, or other body fluids) may be acceptable to the laboratory performing the test
- Occasionally, additional samples may be required to either repeat the test or to perform follow-up testing
- Depending on the location of testing, it may take up to 2 weeks’ turnaround time, to obtain the test results
- Many hospitals preserve the paraffin blocks for at least 7 years. In general, older paraffin blocks (over 5 years) may affect the detection of specific mutations, due to degradation of the tumor specimen over time
Cost of MGMT Mutation Analysis Test:
- The cost of the test procedure depends on a variety of factors, such as the type of your health insurance, annual deductibles, co-pay requirements, out-of-network and in-network of your healthcare providers and healthcare facilities
- In many cases, an estimate may be provided before the test is conducted. The final amount may depend upon the findings during the test procedure and post-operative care that is necessary (if any)
What is the Significance of the MGMT Mutation Analysis Test Result?
- A mutation in the MGMT gene indicates a positive result for the MGMT Mutation Analysis Test. This may mean that an individual is likely to respond well to alkylating chemotherapy such as temozolomide
The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.
Additional and Relevant Useful Information:
- MGMT mutation most notably occurs in a location of the chromosome called 10q36 - i.e., the long arm (q) of chromosome 10 in position 36
- Many laboratories may not have the capability to perform this test. Only highly-specialized labs with advanced facilities and testing procedures may perform this test
Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.
What are some Useful Resources for Additional Information?
The following DoveMed website link is a useful resource for additional information:
Please visit our Laboratory Procedures Center for more physician-approved health information:
References and Information Sources used for the Article:
https://ghr.nlm.nih.gov/primer/testing/genetictesting (accessed on 05/10/2017)
https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5806a1.htm (accessed on 05/10/2017)
http://www.nature.com/gim/journal/v10/n5/full/gim200852a.html (accessed on 05/10/2017)
http://pediatrics.aappublications.org/content/106/6/1494 (accessed on 05/10/2017)
MGMT - Clinical: MGMT Promoter Methylation, Tumor. (n.d.). Retrieved from http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/36733
UC San Diego Health System. (n.d.). MGMT methylation and ... Retrieved from http://neurosurgery.ucsd.edu/brain-tumor-research-mgmt/
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