What are other Names for this Test? (Equivalent Terms)
- Cluster of Differentiation 79B Mutation Analysis Test
What is CD79B Mutation Analysis Test? (Background Information)
- CD79B mutation refers to an alteration in the CD79B gene, which is associated with cancer of the lymphocytes (lymphoma). The mutation is linked to diffuse large B cell lymphoma (DLBCL), the most common form of non-Hodgkin’s lymphoma
- The CD79B gene gives instructions for a protein necessary for the NF-kB pathway. NF-kB is a signaling framework used by immune cells, such as lymphocytes, to survive, grow, divide, and differentiate
- NF-kB is also a protective mechanism that guards against lymphocytes turning into cancer cells. CD79B is a receptor located on the outer membranes of lymphocytes. CD79B recognizes certain compounds, called antigens, outside of the cell and binds them
- Once bound, CD79B initiates a chain of events inside the cell that cause important changes in growth and division via the NF-kB pathway. Thus, CD79B enables the many proteins of the NF-kB pathway to properly perform their functions
- However, mutations in the CD79B gene result in a defective CD79B protein that causes the NF-kB pathway to work incorrectly in the lymphocytes. The result is an increased risk for cancers such as DLBCL
- The CD79B Mutation Analysis Test is a genetic test to detect abnormalities in the CD79B gene. It aids in diagnosis of diffuse large B cell lymphoma. It also aids in the treatment of DLBCL by guiding selection of therapeutic drugs, including disqualifying certain drugs from being used
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 CD79B Mutation Analysis Test?
Following are the clinical indications for performing the CD79B Mutation Analysis Test:
- Swollen, but painless, lymph nodes
- Abdominal swelling
- Fever, night sweats
- Rapid, unexplained weight loss
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 CD79B Mutation Analysis Test?
Following is the specimen collection process for CD79B 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 CD79B 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 CD79B Mutation Analysis Test Result?
- A mutation in the CD79B gene indicates a positive result for the CD79B Mutation Analysis Test
- This may point to a diagnosis of diffuse large B-cell lymphoma (DLBCL)
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:
- The CD79B gene is also associated with a condition called agammaglobulinemia, in which antibody numbers are reduced and the immune system is compromised
- 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 of 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)
Diffuse large B-cell lymphoma | Lymphoma Association. (n.d.). Retrieved from https://www.lymphomas.org.uk/about-lymphoma/types/non-hodgkin-lymphoma/diffuse-large-b-cell-lymphoma
Kraan, W., Horlings, H. M., Van Keimpema, M., Schilder-Tol, E. J., Oud, M. E., Scheepstra, C., … Pals, S. T. (2013). High prevalence of oncogenic MYD88 and CD79B mutations in diffuse large B-cell lymphomas presenting at immune-privileged sites. Blood Cancer Journal, 3(9), e139. doi:10.1038/bcj.2013.28
Yamada, S., Ishida, Y., Matsuno, A., & Yamazaki, K. (2015). Primary diffuse large B-cell lymphomas of central nervous system exhibit remarkably high prevalence of oncogenic MYD88 and CD79B mutations. Leukemia & Lymphoma, 56(7), 2141-2145. doi:10.3109/10428194.2014.979413
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