[Detection of FLT3 gene mutation in hematologic malignancies and its clinical significance]

To study the FLT3 gene expression and its internal tandem duplication in hematologic malignancies and its clinical significance, polymerase chain reaction (PCR) and DNA sequencing were used to detect the FLT3/ITD mutation in blast cells of bone marrow from 86 patients with hematologic malignancies, including 32 cases of acute myeoloid leukemia (AML), 18 cases of acute lymphoblastic leukemia (ALL), 2 cases of acute hybrid leukemia (AHL), 12 cases of myelodysplastic syndromes (MDS), 10 cases of chronic myelogenous leukemia (CML), 3 cases of non-Hodgkin's lymphoma (NHL) and 9 cases of multiple myeloma (MM). The resultes showed that the expression of FLT3/ITD gene could be detected in 5 of 32 (15.6%) AML patients, including 1/7 of M(3), 1/10 of M(4) and 3/10 of M(5). More FLT3 aberrations were found in AML-M(5). No FLT3/ITD was found in 18 cases of ALL, in 2 cases of AHL, in 12 cases of MDS and in 10 cases of CML. No FLT3 was found in 3 cases of NHL and in 9 cases of MM. Sequence analysis in 2 case with abnormal PCR electrophoretic patterns revealed that the ITDs were located within exon 14 from 27 to 63 bp, which was a simple tandem duplication, and did not altered the reading frame. FLT3/ITD was associated with a higher peripheral blood white cell count (p < 0.01), higher percentage of bone marrow blast cells (p < 0.01) and lower complete mission rate. It is concluded that more FLT3/ITD mutation occurs in AML-M(5) patients. Sequence of the mutants is in frame mutation. FLT3/ITD mutation is associated with higher peripheral blood white cell count, higher percentage of bone marrow blast cells and lower complete remission rate, FIT3/IID gene mutation may be used to predict prognosis of patients with AML.