Fluorescence In Situ Hybridization (FISH) for PML/RARα t(15;17) is a diagnostic and prognostic molecular cytogenetic test employed to detect the chromosomal translocation t(15;17) which involves the rearrangement of the PML gene on chromosome 15 and the RARα gene on chromosome 17. This translocation is characteristic of Acute Promyelocytic Leukemia (APL), a subtype of Acute Myeloid Leukemia (AML). APL is a blood cancer that affects the growth of promyelocytes, a type of immature white blood cell, leading to an accumulation of abnormal cells and the suppression of normal bone marrow function.
The PML/RARα fusion gene is formed as a result of the t(15;17) translocation, and it codes for an abnormal fusion protein. This protein interferes with the normal maturation of promyelocytes, leading to the accumulation of these cells in the bone marrow and peripheral blood. APL can manifest with symptoms such as fatigue, increased susceptibility to infections, and abnormal bleeding due to the suppression of normal bone marrow function.
Identifying the presence of the PML/RARα t(15;17) translocation is crucial in confirming the diagnosis of APL and guiding the choice of therapy, as APL is a highly aggressive malignancy but also highly responsive to specific treatments, particularly treatments that include all-trans retinoic acid (ATRA) and arsenic trioxide.
FISH is a method that uses fluorescent probes to visualize specific DNA sequences on chromosomes. In the case of PML/RARα t(15;17), the probes are designed to bind to the PML gene on chromosome 15 and the RARα gene on chromosome 17. Under a fluorescence microscope, if the two probes are seen to be in close proximity or fused together, this indicates the presence of the t(15;17) translocation.
Diagnostic: FISH for PML/RARα t(15;17) is an essential diagnostic tool for APL, as the presence of this translocation is considered a hallmark of this leukemia subtype.
Prognostic: The presence of the PML/RARα fusion gene is associated with a highly favorable response to therapies that include ATRA and arsenic trioxide. Patients without this translocation may not have the same response.
Monitoring: FISH can be used to monitor the response to treatment by assessing the clearance of cells containing the PML/RARα fusion gene.
Test NameFISH for PML/RARα t(15;17)
Sample TypeBlood or Bone Marrow
Preparations RequiredNo special patient preparation is needed.
Report Time4 days
Who should consider taking this test?
Patients who have been diagnosed with AML and have morphologic features suggestive of APL should be tested for the PML/RARα t(15;17) translocation.
What does a positive result mean?
A positive result indicates the presence of the t(15;17) translocation and confirms the diagnosis of APL. It also means that the patient is likely to benefit from therapy that includes ATRA and arsenic trioxide.
Home Sample Collection Process
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Book your convenient slot
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Sample Collection by Phlebotomist
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Reporting of the sample at lab
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Frequently Asked Questions
A negative result indicates that the t(15;17) translocation is not present. This information is useful for ruling out APL as a diagnosis. The patient's symptoms may be caused by another type of leukemia or another condition.
The mainstays of APL treatment are all-trans retinoic acid (ATRA) and arsenic trioxide. These agents can induce complete remission in most patients. In some cases, chemotherapy may also be used.
No, there are alternative methods such as reverse-transcriptase PCR (RT-PCR) and conventional karyotyping. However, FISH is often preferred due to its rapid turnaround time and sensitivity.
FISH for PML/RARα t(15;17) is an invaluable diagnostic and prognostic tool in the management of APL. Early and accurate detection of this translocation enables prompt initiation of targeted therapy, which can significantly improve the prognosis of patients with this aggressive form of leukemia.
