Spotlight on the diagnosis of acute promyelocytic leukemia (AML-M3) using karyotyping, fish and quantitative real-time pcr

Objective : this study aimed to confirm the diagnosis of AML-M3 and the frequency of occurrence of the breakpoint cluster region (bcrl) in patients provisionally diagnosed according to FAB classification. Cytologenetic and molecular genetics methods were used. Methods : bone marrow (BM) or Peripheral Blood (PB) samples collected from 27 AML-M3 patients (During the period 2005 through 2007) were subjected to conventional karyotyping G-banding, detection oft (15 ; 17) was performed by Fluorescence In Situ Hybridization (FISH) and PML-RARA gene rearrangements were detected by Quantitative Real-Time Reverse Transcriptase Polymerase Chain Reaction (QR-RT-PCR). Results : karyotyping was successful in 24 out of 27 samples. Four patients out of 24 had a t (15 ; 17), 17 had normal karyotype and 3 had other abnormalities. The results obtained by FISH technique corresponded with karyotype results and revealed positivity in another 3 samples. QR-RT-PCR demonstrated bcrl positivity in the 4 patients diagnosed by Karyotyping with t (15 ;17) and in the 8 patients cannot diagnosed by Cytogenetic methods. Conclusion : despite the fact that cytogenetic permit the identification of many chromosomal changes within a sample, FISH analysis is more sensitive when the karyotype fails to find out the t (15 ; 17). Furthermore, QR-RT-PCR appears to be the only suitable approach to detect the molecular events underlying hematological malignancies and provides information's on the correlation between different levels of disease at early phases of therapy and clinical outcome.