Flow cytometry in detection of Nucleophosmin 1 mutation in acute myeloid leukemia patients: A reproducible tertiary hospital experience

Abstract

Introduction Nucleophosmin 1 (NPM1) mutation is one of the most frequent gene mutations in adult acute myeloid leukemia (AML), being detected in 35% of all cases and in up to 60% of patients with normal karyotype AML. AML with mutated NPM1 has distinct pathology, immunophenotyping, and confirmed favorable prognostic significance. Hence, AML with mutated NPM1 is a separate entity in the revised 2016 World Health Organization classification. This study aimed to evaluate the use of a reproducible flow cytometry approach in the assay of mutant NPM1 protein in AML patients and to correlate flow cytometric results with the NPM1 gene mutation. Methods Eighty‐nine newly diagnosed AML patients were evaluated for the expression of mutant NPM1 using flow cytometry and for the presence of NPM1 exon 12 mutations using high‐resolution melting polymerase chain reaction (HRM PCR). Results The NPM1 mutation was found in 35 (39.3%) patients by HRM PCR. These patients showed a significantly higher level of percentage of positive‐stained cells (% positive cells) and normalized median fluorescence intensity (MFI) for mutant NPM1 by flow cytometry than the negative mutation group. Conclusion Flow cytometric detection of mutant NPM1 offers a possible tool to indicate NPM1 mutational status.