Acute myeloid leukaemia with FLT3 gene mutations of both internal tandem duplication and point mutation type.

FLT3 gene mutations, either internal tandem duplication or point mutation type, are common in acute myeloid leukaemia (AML). We describe 21 AML cases with both types of gene mutations, so-called dual mutations, representing approximately 1% of all cases. Most newly diagnosed AML with FLT3 dual mutations had monocytic differentiation and a normal karyotype. Over the disease course, changes in FLT3 mutation status were seen in 89% of cases, and were associated with cytogenetic changes. We conclude that FLT3 dual mutations occur rarely in AML, and appear to be related to clonal evolution.