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What is a FISH Bone Marrow Biopsy?

FISH is an acronym for fluorescence in-situ hybridization, a biochemical technique used to study genes in cells. By taking a sample of your bone marrow, the soft tissue inside your bone, doctors can use the FISH technique to test for certain abnormalities that may help determine how to treat cancers like leukemia.

  1. Bone Marrow Biopsy

    • Bone marrow is the soft tissue inside your bones; hematopoietic stem cells (HSCs) in your bone marrow divide to give rise to different cell types like red blood cells that replenish your bloodstream. Accumulated DNA damage in HSCs can cause them to become cancerous and proliferate out of control. If a blood test reveals an abnormal white blood cell count, your doctor may perform a bone marrow biopsy and have it tested for genetic abnormalities using techniques like FISH.

    FISH

    • Two single-stranded DNA molecules that have complementary sequences will hybridize to form double-stranded DNA. Scientists tag a single-stranded DNA (ssDNA) with a fluorescent molecule; this ssDNA is called a probe. The lab technician takes the DNA from the bone marrow cells, denatures it so that it separates into single strands and fixes it to slides. By mixing the probe with the sample DNA, the technician can check to see if the glowing probe hybridizes with the sample DNA. This will determine whether the probe DNA sequence is present in the DNA sample. Scientists can also label RNA molecules in the same fashion and use a similar procedure to determine whether a given gene is active in cells from a sample as well.

    Biopsy Procedure

    • Doctors administer local anesthetic before performing a bone marrow biopsy. During the procedure, the patient lies on his stomach while a biopsy needle is inserted through the skin directly into the bone to withdraw a sample; generally the pelvis is used. The sample is then forwarded to a lab for analysis.

    Uses in Leukemia

    • Genetic tests like FISH offer doctors valuable information that can help them diagnose disorders and choose the right treatment. Leukemia cells with certain mutations respond better to some treatments than others. For example, patients with a mutation that fuses the RARA gene on chromosome 17 with the PML gene on chromosome 15 seems unusually susceptible to high-dose treatment with retinoic acid. There are other mutations that can help doctors determine how serious your condition is or how quickly it may progress.

    Considerations

    • FISH is not the only technique used to analyze genetic defects in bone marrow biopsy cells from leukemia patients; there are other older cytogenetic techniques still in common use. FISH can, however, detect certain mutations that wouldn't be detected using the older techniques. This makes it valuable in diagnosing patients with some types of leukemia. As always, none of the above is intended as medical advice; if you have any questions about the right treatment for your condition, the best person to consult is your doctor.

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