Detection and characterization of FLT3 gene variants in patients with Acute Myeloid Leukemia

BESTACH, YESICA; ORELLANA TORRES, CARLA; LARRIPA, IRENE; CAMACHO, MARÍA FERNANDA; BELLI, CAROLINA

Ciudad Autónoma de Buenos Aires

Congreso; REUNIÓN DE SOCIEDADES DE BIOCIENCIAS 2020: SAIC; SAI, SAFIS; 2020

SAIC, SAFIS y SAI

FLT3 gene is altered in 30% of patients with Acute Myeloid Leukemia AML) associated with a worse prognosis. They are missense variants affecting residues D835-I836 in the tyrosin-kinase domain 2 (TKD) and internal tandem duplications (ITD) within the juxtamembrane domain.Our aim was to detect the presence of these variants and to describe their characteristics in patients with newly diagnosed AML.Samples from 215 patients with AML diagnosed between May-18 to Jan-20 were analyzed. DNA extraction was carried out with commercial columns from mononuclear isolated cells. Detection of ITD (spanning exons 13-14) was performed by PCR amplification, agarose gel visualization, and capillary electrophoresis to calculate the allelic ratio, while TKD (exon 20) by PCR-RFLP and agarose gel visualization. Both variants were characterized by automatic sequencing.FLT3(+) were detected in 61 (28%) patients (43 ITD, 13 TKD and 5 ITD/TKD), presenting medians (Mdn) of age of 53 years, blasts 75%, and higher white blood cell counts 93396 (vs 34149/µL FLT3-wt, T test, pT (p.Asp835Tyr), 1 c.2503G>C (p.Asp835His), 1 c.2505T>C (Asp835=), 1 c.2504_2508delATATCinsTT (p.Asp835_Ile836delinsVal) and 1 c.2502_2504delAGA, (p.Asp835del). These last 2 variants were novels.The results obtained show a frequency of mutations in FLT3 of 30%, consistent with the reference literature, with a predominance of IDT vs TKD. Detection by PCR and capillary electrophoresis allowed highly sensitive and specific results. The characterization and range of the sequence variants found in IDT and TKD correspond to what was published in the query databases.