Test Directory

• PML, 15q24.1
• RARA, 17q21.1-q21.2

The genetic hallmark of acute promyelocytic leukemia (APL) is a balanced chromosomal translocation t(15;17)(q24;q21) leading to fusion of the promyelocytic leukemia (PML) and the retinoic acid receptor alpha (RARA) genes. The fusion gene results in a chimeric PML::RARA oncoprotein, which plays a causative role in APL pathogenesis impairing myeloid differentiation. The resulting PML::RARA protein silences genes that are critical for cell differentiation, resulting in both a differentiation block and an expansion of myeloid progenitors. Acute promyelocytic leukemia (APL) accounts for 10% of adult myeloid leukemia. Although all patients with APL have t(15;17) or a variant of this translocation, conventional cytogenetic methods detect these translocations in only 70–96% of patients at diagnosis.

FISH for abnormalities of chromosome PML::RARA can be performed on interphase or metaphase cells.

Specimen Types: Leukemic Blood or Bone Marrow

Preferred Collection Container: Green Top (Sodium Heparin)

Alternate Collection Container: Lavendar Top (EDTA)

Desired Specimen Volume: 3 - 5 mL

Minimum Acceptable Volume: 1 mL

• Lithium heparin is not acceptable.
• Specimens must be collected in a sterile collection container.

Each specimen must be accompanied by a requisition form, script, electronic order or physician note. Each order must indicate the reason for testing (diagnosis).

• Transport to the laboratory at room temperature.
• Store specimen as whole blood, in original tube, at room temperature and deliver to lab within 24 hours.
• If specimen cannot be delivered within 24 hours, store in refrigerator. Do not freeze specimen.
• Specimens collected on the weekends must be refrigerated upon arrival at HNL Lab Medicine.

• Specimen frozen
• Specimen arriving without any form of patient identification (unlabeled)
• Specimen with attached needles
• Specimen arriving with broken or leaking collection tube
• Unfixed specimen treated with fixative

In a normal cell, the expected signal pattern is two red signals and two green signals. In an abnormal cell containing a typical translocation, the expected signal pattern is one red signal, one green signal, and two fused signals.

• FISH PML RARA
• APL
• t(15;17)
• PML::RARA
• Promyelocytic Leukemia