急性髓系白血病NPM1基因突变检测的临床意义

目的 探讨初诊急性髓细胞白血病(acute myeloid leukemia,AML)患者NPM1基因突变发生率及其与染色体核型和FAB亚型之间的关系,并分析NPM1基因的突变类型.方法 选取2004至2010年中日友好医院血液科99例初诊AML患者.采集患者骨髓标本,采用聚合酶链反应(polymerase chain reaction,PCR)扩增基因组DNA,并采用变性聚丙烯酰胺凝胶电泳(polyacrylamide gel electrophoresis,PAGE)和毛细管电泳两种方法对AML患者NPM1基因突变进行检测.应用G显带方法对其中72例初诊AML患者进行细胞遗传学分析,同时对10例NPM1突变阳性患者进行直接测序分析.NPM1插入突变在各亚型患者中发生率的比较采用x2检验.变性PAGE和毛细管电泳两种方法检测NPM1基因突变发生率的比较采用McNemar检验.结果 毛细管电泳法与变性PAGE法检测AML患者NPM1基因插入突变发生率分别为15％ (15/99)和11％ (11/99),差异无统计学意义(x2 =2.25,P＞0.05).NPM1插入突变在各亚型患者中发生率分别为:急性粒细胞白血病部分分化型(M2)(27％,8/30)、急性单核细胞白血病(M5)(32％,6/19)、红白血病(M6)(13％,1/8),差异无统计学意义(x2=1.06,P＞0.05),其余亚型未检测到NPM1插入突变.49例AML异常核型患者的NPM1插入突变发生率为4％ (2/49),23例正常核型患者的NPM1插入突变发生率为26％ (6/23),差异有统计学意义(x2=5.61,P＜0.05).10例NPM1基因插入突变均为A型突变(c.860_863 dupTCTG).突变导致NPM蛋白羧基末端读码框移,末尾7个氨基酸WQWRKSL被11个氨基酸CLAVEEVSLRK所代替.2例患者检测到内含子缺失突变,分别为IVS10-18_-15delCTTT和IVS10-17-15delTTT.结论 NPM1插入突变为AML患者常见基因改变,正常核型患者插入突变发生率高于异常核型患者.在NPM1基因内含子区发现2例缺失突变.

Detection of NPM1 gene mutation in acute myeloid leukemia

Objective To analyze the frequency of NPM1 mutation in de novo acute myeloid leukemia (AML) patients and the relationship between NPM1 mutation and chromosome alterations,as well as FAB subgroups,and to analyze the mutation type.Methods A total of 99 de novo AML patients from 2004 to 2010 in China-Japan Friendship Hospital were studied.Genomic DNA was amplified by polymerase chain reaction (PCR),denaturing polyacrylamide gel electrophoresis (PAGE) and capillary electrophoresis were used to detect the mutation of NPM1 gene in 99 AML patients,and karyotyping was performed in 72 AML patients by G banding techniques.DNA sequences analysis of NPM1 mutation was performed on 10 patients.Chi-square test was used to compare the frequencies of NPM1 mutation among the different subgroups,and McNemar's test was used to compare the different rates between denaturing PAGE and capillary electrophoresis.Results The frequencies of NPM1 mutations were detected in 15％ (15/99) of AML patients with capillary electrophoresis and 11％ (11/99 ) with denaturing PAGE(x2 =2.25,P ＞0.05 ).The NPM1 was at different rates in M2(27％,8/30),M5(32％,6/19),M6( 13％,1/8),respectively (x2 =1.06,P ＞ 0.05 ),and not detected in the other subgroups.NPM1 mutation in patients with normal karyotype(26％ ) was more prevalent than patients with abnormal karyotype (4％) (x2 =5.61,P ＜ 0.05)All of the 10 patients were of A type ( c.860_863dupTCTG).The C-terminal portion of the NPM protein by replacing the last seven amino acids(WQWRKSL) with 11 residues (CLAVEEVSLRK).Two intronic deletions were novel,one case was IVS10-18_-15delCTTT,the other was IVS10-17_-15delTTT.Conclusions NPM1 mutations represents a common genetic abnormality in AML patients,and NPM1 mutation in patients with normal karyotype is higher than patients with abnormal karyotype.Two new intronic deletion mutations are identified.