XL RARA BA

Break Apart Probe

Order Number
D-5087-100-OG
Package Size
100 µl
Labels
  
Chromosome
17

Description

XL RARA BA

XL RARA BA is designed as a break apart probe. The orange labeled probe hybridizes proximal to the breakpoint in the RARA gene region at 17q21, the green labeled probe hybridizes distal to the breakpoint.

Clinical Details

Acute promyelocytic leukemia (APL) is considered as a subtype of acute myeloid leukemia (AML) and accounts for about 5-8% of all AML cases. The most frequent aberration in APL is t(15;17) which results in the formation of the promyelocytic leukemia (PML) - retinoic acid receptor alpha (RARA) fusion gene (PML-RARA). Around 98% of all APL cases are characterized by PML-RARA whereas translocations affecting RARA and other genes have been identified in only 1-2% of APL cases. Known fusion genes are ZBTB16-RARA, NPM1-RARA, NUMA1-RARA, STAT5B-RARA, PRKAR1A-RARA, BCOR-RARA and FIP1L1-RARA. ZBTB16-RARA comprises about 0.8% of all APL cases, the other rare fusions occur with lower frequency. Cryptic rearrangements resulting in the PML-RARA fusion gene are observed regularly, but also insertions of RARA into other locations have been found in a minority of APL cases. RARA is a nuclear hormone receptor which forms heterodimers with the retinoid X receptor alpha and is involved in the regulation of promyelocyte differentiation. RARA fusion genes interfere with myeloid differentiation and contribute in the development of APL. The majority of APL patients are responsive to therapeutic doses of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) associated with chemotherapeutic drug regimen. Patients with ZBTB16-RARA or STAT5B-RARA fusions are resistant to ATRA and ATO. The FISH break apart assay is a valuable tool for the detection of RARA rearrangements independent of the translocation partner.

Clinical Applications

  • Acute Myelogenous Leukemia (AML)

Images

XL RARA BA

XL RARA BA hybridized to bone marrow cells. One aberrant interphase with two colocalization/fusion signals and one additional green signal is shown, indicating an insertion of RARA into another chromosome.

Expected Patterns

Expected Pattern 1

Normal Cell:
Two green-orange fusion signals (2GO).

Expected Pattern 2

Aberrant Cell (typical results):
One green-orange colocalization/fusion signal (1GO), one separate green (1G) and orange (1O) signal each resulting from a chromosome break in the respective locus.

Literature

  • Grimwade et al (2000) Blood 15:1297-1308
  • Schoch et al (2002) Hematol J 3:259-263
  • Adams and Nassiri (2015) Arch Pathol Lab Med 139:1308-1313

Downloads

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