Diagnostic utility of dual fusion PML/RARα translocation DNA probe (D-FISH) in acute promyelocytic leukemia

Abstract

Translocation(15;17) leading to the formation of fusion gene PML/RAR• is the diagnostic hallmark of acute promyelocytic leukemia (APL). Interphase fluorescence in situ hybridization (FISH) is one of the diagnostic tools employed for the detection of PML/RAR• rearrangement. Using a dual color dual fusion (D-FISH) PML/RAR• translocation DNA probe which hybridises both to PML/RAR• and RAR•/PML fusion genes, we characterised the FISH pattern of 52 APL patients at diagnosis and correlated the findings with conventional cytogenetics and RT-PCR analysis. The diagnostic sensitivity of the probe for PML/RAR• was 100%. Seven patients had atypical D-FISH patterns; two had a masked PML/RAR• fusion signal caused by the insertion of PML into RAR• on 17q; 3 had an extra copy of PML/RAR• in the form of isochromosome der(17)(q10)t(15;17) and one had duplication of the normal RAR• gene with an ider(17q) masquerading as i(17)(q10). There was also one case of t(7;17;15) with a typical D-FISH pattern and in which metaphase FISH suggested an unusual 4-point break. In summary, PML/RAR• D-FISH is a highly sensitive method for confirming diagnosis of APL. However D-FISH cannot be solely relied on for the diagnosis of APL owing to atypical patterns which are infrequently observed in cases with additional 17q structural abnormalities, gene insertion and gene duplication.

De novo hairy cell leukemia with a major BCR/ABL1 rearrangement: A case report with a literature review

“…It is well known that Bouin's fixative will destroy DNA and RNA and is suboptimal for FISH experiments. Therefore, we performed FISH on unstained BM aspirate slides . Two orange signals ( ABL1 ) and two green signals ( BCR ) could be observed among the 45 cells analyzed, demonstrating that the BCR/ABL1 fusion was negative in hairy cells.…”

“…Hairy cell leukemia (HCL) is a mature B‐cell neoplasm characterized by lymphocytes with hair‐like cytoplasmic projections infiltrating the bone marrow (BM) and spleen, leading to pancytopenia, BM fibrosis, and splenic enlargement . Even though it is a rare disease comprising only 2% of all leukemia cases, occurrence of a secondary malignancy in patients with HCL has been well recognized . For example, HCL showed subsequent malignancies in 8.7% of cases, which typically present as solid tumors .…”

“…1 Even though it is a rare disease comprising only 2% of all leukemia cases, occurrence of a secondary malignancy in patients with HCL has been well recognized. 2 For example, HCL showed subsequent malignancies in 8.7% of cases, which typically present as solid tumors. 3 Also, Philadelphia chromosomepositive chronic myelogenous leukemia (Ph+ CML) develop-ment after HCL diagnosis has been reported in two cases.…”

Acute promyelocytic leukaemia with a PML-RARA insertional translocation and a chromosome 21 abnormality in XYY syndrome: Case report

“…However, complicated translocation variations, including a threeway translocation or the PML-RARA insertion translocation, also exist; these cannot be tested by cytogenetic analysis. 19,20 These cryptic t(15;17)(q22;q21) rearrangements can be detected by molecular methods, such as FISH. The use of the dual colourdual fusion PML/RARA translocation DNA probe with high sensitivity and specificity detects nearly all of the PML-RARA fusion signal of cryptic t(15;17)(q22;q21) rearrangements.…”

FISH Glossary: An Overview of the Fluorescence in Situ Hybridization Technique

“…D-FISH was initially devised to improve detection of the double BCR/ABL fusion in chronic myeloid leukemia (CML) patients (52,53). Subsequently, D-FISH probes were developed for the 8;21 translocation and used for the assessment of minimal residual disease in acute myeloid leukemia (AML) patients during remission (54) and also for the visualization of PML/RARA double fusion in acute promyelocytic leukemia (APL) (55,56), the DEK/CAN double fusion resulting from t(6;9) in AML (57), and the PBX1/E2A double fusion in pediatric patients with acute lymphoblastic leukemia (ALL) (58). A wide range of probes for D-FISH, as well as Fusion-Signal and Split-Signal FISH for the chromosomal analysis of hematological cancer, are now commercially available.…”