Genetic changes including gene copy number alterations and their relation to prognosis in childhood acute myeloid leukemia

Abstract

We studied a series of 68 subjects diagnosed with childhood acute myeloid leukemia (AML) using conventional cytogenetics and fluorescence in situ hybridization (FISH), polymerase chain reaction (PCR) to analyze mutations in FLT3 and NPM1 genes, and/or array comparative genomic hybridization (CGH). Cytogenetic/FISH abnormalities were observed in 71% of subjects, FLT3-ITD mutations in 15%, and NPM1 mutations in 13%. The array CGH alterations (average 3.6 per case) were observed in 96% of the tested subjects. The most frequent alterations were gains of 8q24.3 and 11p15.5-p15.4 in 16% of the samples. Six genes (AKT1, RUNX1, LTB, SDC1, RUNX1T1, and JAK2) from the imbalanced regions have been reported to be involved in AML, whereas other 30 cancer genes, not previously reported in an AML context, were identified as imbalanced. They probably correspond to non passenger alterations that cooperate with the recurrent translocations. The clinical data and genetic changes were tested to find out the possible association with prognosis. Genomic instability (four or more genomic imbalances) was correlated with poor patient outcome (p = 0.029).

Keywords:

• Childhood AML
• cytogenetics
• genetic mutations
• genomic imbalances
• array CGH
• prognosis

Acknowledgements

The authors thank Jessica Martínez, Susana Gaitán, Ángeles Pérez, Laia Puig, and Lorena Ripollés for their help in the experiments. The research group has been recognized as a high quality research group by Generalitat de Catalunya (2005SGR 00164). This work was partially financed by the Spanish National Cancer Network (RD060020/1020) from Ministerio de Sanidad y Consumo.