Molecular Diagnostic Laboratory
Phone: (314) 454-8685; 454-7601
FAX: (314) 454-7616
Barbara Zehnbauer, PhD FACMG
PML/RARA Gene Translocation
Promyelocytic leukemia (APL) t(15;17)
Indications for Molecular Testing
• Suspected or confirmed diagnosis of acute promyelocytic leukemia characterized by t (15; 17)
Following RNA isolation a cDNA copy is synthesized by reverse transcriptase (RT-PCR) using random primers.
Polymerase chain reaction (PCR) amplification follows using the specific primers complementary to the PML
(15q24) and RARA (17q21) sequences of the fusion product. The PCR products are identified by size upon
separation by capillary electrophoresis and fragment sizing.
(PCR is utilized pursuant to a license agreement with Roche Molecular Systems, Inc.)
Interpretation of RNA analysis
Acute promyelogytic (M3) leukemia (APL) is a distinct form of acute myelogenous leukemia (AML) representing
approximately 10% of AML. These leukemias often express PML/RARA transcripts from t(15;17) chromosomal
translocations that fuse the PML gene with the retinoic acid receptor α gene. Three PML/RARA translocation
patterns have been identified: type A is the short (S-Form); the breakpoint occurs within breakpoint cluster region
3 (BCR3). Type B is the long (L-Form); the breakpoint occurs within BCR1. There is a third type B variant of
variable (V-V-Form); the breakpoint is within BCR2. Identification of the PML/RARA rearrangement is important
in APL because it is correlated with responsiveness to treatment with all-trans retinoic acid (ATRA) or arsenic
therapy. The rearranged DNA fragment may also be used as a specific diagnostic marker to detect minimal
residual disease following treatment.
This assay requires the isolation of RNA from the specimen; therefore special handling procedures are required.
Frozen Tissue--10 mm3 of fresh frozen tissue in sterile, plastic container. Forward frozen tissue on dry ice.
Peripheral Blood--1 lavender-top (EDTA) tube. Invert several times to mix blood. Bone Marrow--Place 1-2 mL
of anticoagulated bone marrow in a lavender-top (EDTA) tube. Invert several times to mix bone marrow. Blood
and bone marrow should be delivered to the lab within 4 hours. Overnight storage with refrigeration may
compromise the integrity of the RNA required for accurate testing. Do not freeze, forward promptly at ambient
temperature. NOTE: Abnormal fusion RNA may be less stable within cells than the normal control gene RNA.
Molecular Diagnostic Laboratory
Barnes-Jewish Hospital North, Room 2445 Clinical information must be provided
Mail Stop 90-28-273 with specimen referral in order to
216 South Kingshighway correctly interpret test results.
St. Louis, MO 63110
Available from BJH Laboratory Customer Service at 314-362-1470
CPT codes: 83907, 83890, 83902, 83898, 8390, 83894, 83912.
Miller WH, et al. “RT-PCR for the rearranged RAR clarifies diagnosis and detects minimal residual disease in APL” Proc.
Natl. Acad. Sci. USA 89: 2694, 1992.
InVivoScribe Technologies: PML/RAR t(15;17) Translocation Assay kit, 1311001Xv7.16.
Miller, Jr WH, Kakizuka A, Frankel SR, Warrell, Jr RP, DeBlasio A, Levine K, Evans RM, Dmitrovsjy E. Proc. Natl. Acad. Sci.
USA 89 2694-2698. 1992.