OBJECTIVETo explore the prevalence of IDH gene (IDH1 and IDH2) mutations, types of mutations in patients with acute myeloid leukemia (AML), correlation with the internal tandem duplication(ITD) mutation of FLT3 gene, NPM1 gene mutation and some clinical characteristics.

METHODSThe mutations of IDH1 and IDH2 gene at exon 4, NPM1 gene at exon 12 and FLT3-ITD at exon 14 and 15 in 163 newly diagnosed AML patients were detected by PCR amplification followed by direct sequencing of genomic DNA.

RESULTS(1) IDH mutations were found in 25 patients (25/163), and all were heterozygous, of which IDH1 in 7 patients (4.29%) and IDH2 in 18 (11.04%). A total of 4 types of IDH1 mutations were identified (c.395G→A, p.R132H, n = 4; c.394C→A, p.R132S, n = 1; c.394C→G, p.R132G, n = 1; c.315C→T, n = 1). The IDH1 mutation caused substitutions of residue R132 except for one (c.315C→T). All IDH2 mutations caused changes of R140 (c.419G→A, p.R140Q, n = 18). The incidence of IDH2 mutation was significantly higher than that of IDH1 mutation (11.0% v 4.3%, P = 0.022). Both IDH1 and IDH2 mutation were detected in one patient, while IDH1 was synonymous substitution (c.315C→T). IDH-mutated cases showed a significantly higher frequency of concurrent FLT3-ITD mutation compared with wildtype cases (34.6% vs 11.9%, P = 0.003), so did IDH mutations concurrent NPM1 mutation vs NPM1 wildtype (28.1% vs 12.7%, P = 0.033), of which the frequency of concurrent NPM1 and FLT-ITD mutations cases with the IDH mutation was significantly higher than that of NPM1 and FLT-ITD negative (45.5% vs 11.7%, P = 0.002). IDH mutation incidence was significantly higher in normal karyotype cases than in abnormal ones (20.5% vs 5.8%, P = 0.020). Patients with IDH mutations were significantly older than wildtype patients(P < 0.001), whereas, there were no statistically significant differences in gender, peripheral blood (PB) count at diagnosis between two groups.

CONCLUSIONSThe incidence of IDH mutation is higher in patients with de novo AMLs, of which IDH2 mutation more frequently, and the patients associated with older age, normal karyotype at diagnosis. IDH mutation has a strong association with NPM1 and FLT3-ITD mutations, suggesting that IDH mutation has synergistic effect with the latter gene on leukemogenesis.