FLT3-ITD阳性急性髓系白血病患者ITD特征分析

摘要

本研究分析FLT3-ITD阳性初诊急性髓系白血病(AML)患者FLT3基因突变型与野生型等位基因比值(AR)、ITD数量、ITD长度和部分患者ITD插入位置,以及AR与临床疗效之间的关系.聚合酶链反应(PCR)扩增31例FLT3 -ITD阳性AML患者FLT3基因外显子14-15,毛细管电泳法分析31例患者FLT3基因AR、ITD数量和长度,并对其中13例患者FLT3基因PCR产物直接测序.结果表明,31例FLT3-ITD阳性的AML患者中AR范围为0.01 -2.8;28例(90.32％)患者ITD为1条,3例(9.68％)患者ITD多于1条；ITD长度3-144 bp不等.13例测序患者中4例ITD插入序列为FLT3野生型完全重复,2例为完全陌生碱基插入,7例为野生型部分重复.13例测序患者中ITD插入序列发生在p.E573位至p.P606位之间,多集中于p.F590 -p.R595之间.AR≥0.5患者的CR率(16.67％)低于AR ＜0.5患者的CR率(43.75％)(p＞0.05).结论:FLT3-ITD阳性AML患者中TTD长度和AR范围变化较大.部分患者插入序列为陌生碱基,13例测序患者TTD插入位置较集中,均位于近膜区.AR≥0.5的患者CR率与AR＜0.5的CR率相比无统计学差异.%The aim of this study was to analyze the FMS-like tyrosine kinase 3 internal tandem duplication ( FLT3-ITD) allelic ratios (AR) , number of ITD, ITD length and positions of 1TD insertions in de novo acute myeloid leukemia(AML) patients with FLT3-ITD positive, and the relationship between mutant level and therapeutic efficacy. Genomic DNA was amplified by PCR, capillary electrophoresis was used to detect the ITD characteristics in 31 de novo AML patients, and DNA sequences analysis of FLT3-ITD* were performed in 13 patients. The results showed that the ratios of mutant to wild type FLT3 allele ranged from 0. 01 to 2. 8; 28 patients (90. 32%) had a single ITD, the remaining 3 patients had more than one ITD; the ITD length ranged from 3 to 144 bp in all FLT3-ITD* patients. 13 sequence-analyzed patients, 4 patients were of pure duplications, and 2 patients had foreign bases inserted, and the other 7 patients were partial duplications. The ITD occurred in the regions from p. E573 to p. P606 of the FLT3 protein, with the majority clustered in a stretch between p. F590 and p. R595. The complete remission(CR) rate in AR <0.5 patients (43.75%) were more prevalent as compared with AR> 0.5 patients (16.67%) (p>0.05). It is concluded that the ITD length and AR are vary widely. Some of the insertions are foreign bases, and all of the 13 sequences-analyzed ITD were concentrated on the juxtamembrane domain. The CR rate in patients of AR < 0. 5 had no statistical significance compared with patients of AR>0.5.