FLT3-ITD VARIANT IN ACUTE MYELOID LEUKEMIA PATIENTS TREATED AT A REFERRAL HOSPITAL IN THE STATE OF AMAZONAS

Abstract

Introduction: Acute Myeloid Leukemia (AML) is a hematological disease marked by clonal proliferation neoplasm cells of the myeloid lineage accompanied by genetic alterations. Variants in the FLT3 gene (FMS-like tyrosine kinase 3), as internal tandem duplication mutations (FLT3-ITD), frequently observed in 15-35% AML cases, this variant is associated with unfavorable prognosis in the treatment of the AML. FLT3-ITD variant is related with origin of aggressive and resistant clones, therefore the importance of the screening of the FLT3-ITD in the diagnosis and treatment of the AML. Objective: In this study, we investigate of the FLT3-ITD variant in AML patients treated at Foundation HEMOAM. Materials and methods: Samples of bone marrow from 43 patients were analyses in the AML diagnosis. RNA extraction was performed and screening of the FLT3-ITD variants were detected by conventional Polymerase Chain Reaction (PCR). The amplified products were separated by electrophoresis with a 2% agarose gel. The size identification of the insertion ITD was performed by capillary electrophoresis. Here, we developed a low-cost assay and with high specificity, accord with other electrophoresis methods. Results: In this study, there was a high prevalence of female patients, 25 (58.14%), with age median of 53 years (34 – 71). Among 43 patients analyzed, 7 (16.3%) were FLT3-ITD positive. The size ITD fragments identified were approximately 27-81 bp, 4 patients presented ITD of 81 bp. The amplified product intensity was analyzed in agarose gel by application ImageLab software, the ITD fragments were correlated with Variant Allele Frequency (VAF) present range of 11% to 60%. Discussion: Our study highlights a higher prevalence of AML patients female, when related male subjects more prevalent in other studies. This divergence may be attributed to genetic, environmental and lifestyle conditions specific to our population. In this study, the FLT3-ITD present a frequency of 16.3%, result similar with other Brazilian studies. Ther insertions of ITD were 27 to 81 bp, according with data of previous studies, size ranging from 3 to over 400 bp. Different studies have related ITD larger inserts, as 81 bp, are associated with worse prognosis and higher death rates (60% of the cases). Conclusion: This study revealed distinct characteristics from the Amazonas patients when compared with global AML data, as reported a younger population and prevalence of female patients. Accordingly, the frequency of FLT3-ITD was expected, the detection may favor the patient treatment, we highlight the importance of the screening of the ITD in AML patients.