A Clinical Study On The Relationship Of CEBPA, FLT3-ITD, NPM1and C-KIT Gene Mutations With Acute Myeloid Leukemia

ObjectivesTo analyze the incidence of CEBPA, FLT3-ITD, NPM1and C-KIT genemutations and their mutation types by detecting CEBPA, FLT3-ITD, NPM1andC-KIT gene mutations in treatment-na ve acute myeloid leukemia (AML) patients,and to discuss the distribution of gene mutations and their relationship withhematologic features, karyotype and remission rate after initial induction therapy andto explain the clinical significance.MethodsCEBPA, NPM1and C-KIT gene mutations were detected by PCR combined withgene sequencing; FLT3-ITD gene mutation was detected by PCR combined withagarose gel electrophoresis; karyotype was analyzed by G-banding; the morphologicalfeatures of bone marrow cells and the proportion of immature cells were analyzedmicroscopically after Wright’s stain procedure.Results1. CEBPA, FLT3-ITD, NPM1and C-KIT gene mutations and their incidence inAML patients: Of the279treatment-na ve AML patients, CEBPA mutations weredetected in35patients, FLT3-ITD mutations in49patients, NPM1mutations in40patients, and C-KIT mutations in9patients. The incidences of these four genemutations in AML patients were12.54%,17.56%,14.34%and3.2%respectively.A comprehensive analysis of all279patients revealed that all mutations weredistributed in111patients. Of these111patients,21had more than one differentgene mutations simultaneously, with FLT3-ITD and NPM1simultaneousmutations most frequently observed, and patients with CEBPA single mutationswere more likely to be accompanied by FLT3-ITD and NMP1gene mutations than patients with CEBPA double mutations.2. Types of CEBPA, FLT3-ITD, NPM1and C-KIT gene mutations in AML patients:Of the35cases of CEBPA mutations,31were double mutations and4were singlemutations; for NPM1gene mutations, type A mutation (77.5%) was most frequent,followed by type B and type D; for C-KIT gene mutations, D816mutation in exon17was most frequent.3. CEBPA, FLT3-ITD, NPM1and C-KIT gene mutations and FAB subtypes: CEBPAmutations were observed in M2, M4, M5and M6patients and not in M1and M3patients. Also, CEBPA mutation detection rate in M2patients was higher inpatients with other subtypes (P <0.05). FLT3-ITD mutations were observed in allFAB types M1-M6. FLT3-ITD mutations were the only type of mutations for M3patients and the incidence was high in M1patients. NPM1mutations wereobserved in all FAB types other than M3and had high incidence in M1patients.C-KIT mutations were mainly observed in M2patients.4. CEBPA, FLT3-ITD, NPM1and C-KIT gene mutations and hematologic featuresof AML patients: patients with mutations compared with wild type patients:1)patients with CEBPA double mutations had higher WBC count, RBC count andhemoglobin level and lower age and platelet count;2) patients with FLT3-ITDmutations had higher WBC count, proportion of immature cells in the bonemarrow, and females had higher incidence;3) patients with NPM1mutations hadhigher age, WBC count, proportion of immature cells in the bone marrow andplatelet count;4) patients with C-KIT mutations had lower platelet count;inter-group difference in all these aspects was statistically significant (P <0.05).5. CEBPA, FLT3-ITD, NPM1and C-KIT gene mutations and karyotype of AMLpatients: CEBPA, FLT3-ITD and NPM1mutations were mainly observed inpatients with a normal karyotype. These three types of mutations had higherdetection rate in patients with a normal karyotype than in patients with anabnormal karyotype and in all AML patients as a whole. C-KIT mutations hadhigher incidence in patients with an abnormal karyotype and were mainlyobserved in core binding factor AML (CBF-AML). 6. Effect of CEBPA, FLT3-ITD, NPM1and C-KIT gene mutations on remission rateafter initial induction therapy:1) In AML group, patients with mutations comparedwith wild type patients: patients with CEBPA double mutations and NPM1mutations had higher rate of complete remission (CR) after initial inductiontherapy, while patients with FT3-ITD mutations and C-KIT mutations had lowerCR rate after initial induction therapy.2) For patients with a normal karyotype,when they were divided into four groups based on their FLT3-ITD and NMP1mutation status, CR rates in descending order were FLT3-ITD-/NPM1+group>FLT3-ITD+/NPM1+group>FLT3-ITD-/NPM1-group> FLT3-ITD+/NPM1-group; when they were divided into four groups according to their FLT3-ITD andCEBPA mutation status, CR rates in descending order were FLT3-ITD-/CEBPA+group> FLT3-ITD+/CEBPA+group> FLT3-ITD-/CEBPA-group>FLT3-ITD+/CEBPA-group.Conclusions1. The incidences of the four mutations investigated in this study were FLT3-ITD,CEBPA, NPM and C-KIT1in descending order. As for the mutation types,CEBPA gene showed double mutations predominantly, type A mutation was mostfrequent for NPM1gene, and D816mutation in exon17was most frequent forC-KIT gene.2. CEBPA, FLT3-ITD, NPM1and C-KIT gene mutations were variously distributedin AML FAB types, specifically, CEBPA mutations were mainly observed in M2,NPM1mutations were observed in all FAB types other than M3, and FLT3-ITDmutations was the only type of mutations for M3patients.3. Patients with gene mutations were different in age, gender, proportion of immaturecells in the bone marrow and hematologic features compared with wild typepatients.4. CEBPA, FLT3-ITD and NPM1mutations mainly occurred in AML patients with anormal karyotype, while C-KIT mutations were mainly observed in CBF-AMLpatients5. Patients with CEBPA and NPM1mutations had higher CR rate after initial induction therapy, while patients with FT3-ITD mutations had lower CRrate,suggesting that NPM1and CEBPA mutations indicate good prognosis ofAML, while FLT3-ITD indicates bad prognosis of AML.