Acute promyelocytic leukemia: the study of t(15;17) translocation by fluorescent in situ hybridization, reverse transcriptase-polymerase chain reaction and cytogenetic techniques

Abstract

Acute promyelocytic leukemia (AML M3) is a well-defined subtype of leukemia with specific and peculiar characteristics. Immediate identification of t(15;17) or the PML/RARA gene rearrangement is fundamental for treatment. The objective of the present study was to compare fluorescent in situ hybridization (FISH), reverse transcriptasepolymerase chain reaction (RT-PCR) and karyotyping in 18 samples (12 at diagnosis and 6 after treatment) from 13 AML M3 patients. Bone marrow samples were submitted to karyotype G-banding, FISH and RT-PCR. At diagnosis, cytogenetics was successful in 10 of 12 samples, 8 with t(15;17) and 2 without. FISH was positive in 11/12 cases (one had no cells for analysis) and positivity varied from 25 to 93% (mean: 56%). RT-PCR was done in 6/12 cases and all were positive. Four of 8 patients with t(15;17) presented positive RT-PCR as well as 2 without metaphases. The lack of RT-PCR results in the other samples was due to poor quality RNA. When the three tests were compared at diagnosis, karyotyping presented the translocation in 80% of the tested samples while FISH and RT-PCR showed the PML/ RARA rearrangement in 100% of them. Of 6 samples evaluated after treatment, 3 showed a normal karyotype, 1 persistence of an abnormal clone and 2 no metaphases. FISH was negative in 4 samples studied and 2 had no material for analysis. RT-PCR was positive in 4 (2 of which showed negative FISH, indicating residual disease) and negative in 2. When the three tests were compared after treatment, they showed concordance in 2 of 6 samples or, when there were not enough cells for all tests, concordance between karyotype and RT-PCR in one. At remission, RT-PCR was the most sensitive test in detecting residual disease, as expected (positive in 4/6 samples). An incidence of about 40% of 5 breaks and 60% of 3 breaks, i.e., bcr3 and bcr1/bcr2, respectively, was observed.

Increased Risk of Acute Myeloid Leukemia in Patients with <i>CYP</i>1<i>A</i>1 Polymorphisms

“…Interestingly, in other medical settings such as solid tumors there is an increased risk for solid tumors in patients with CYP1A1 * 2A and CYP1A1 * 2C genotypes. Such evidence was reported in non-small cell lung cancer and head and neck cancer in Australian and Indian patients, respectively [10][11][12]. Experimental data from in vitro studies show that enzyme activity of CYP1A1 * 2C, is normal, but no further data support if this polymorphism in vivo can harbor a protective role to prevent DNA injury.…”

“…There were 51 de novo AML and 7 secondary AML. AML was classified according to previously standardized WHO criteria, [1,12,13]. Thus, AML patients were categorized into three cytogenetic groups [1,12,13].…”

“…The genetic component of AML etiology is likely to be polygenic, and the identification of further candidate genes is essential for future studies and assessment of AML risk-related genes [10][11][12]. From previous studies, the results obtained are controversial and require further investigation to confirm or clarify the data obtained.…”

Prevalence of FMS-like tyrosine kinase 3/internal tandem duplication (FLT3/ITD+) in de novo acute myeloid leukemia patients categorized according to cytogenetic risk

“…According to the chromosomal abnormality classification, 13 A = acute myeloid leukemia with recurrent chromosomal abnormalities; B = acute myeloid leukemia with multilineage dysplasia; C = acute myeloid leukemia after therapy (chemo or radio); D = acute myeloid leukemia not categorized; M = male; F = female. Table 1.…”

“…These were harvested after 24 hours and slides from these cultures were banded using the Trypsin-Giemsa technique (GTG). 13 The metaphases were analyzed using an image capture system (Olympus BX microscope and Cytovision data processing through Applied Biosystems). The abnormalities were described in accordance with the International System for Human Cytogenetic Nomenclature (ISCN).…”