Myeloid Leukemia

FLT3 Mutations in AML 189
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FLT3 Mutations in Acute Myeloid Leukemia
Hitoshi Kiyoi and Tomoki Naoe
Summary
The prevalence of an internal tandem duplication (ITD) of the juxtamembrane domain-coding
sequence and a missense mutation of D835 within the kinase domain of the FLT3 gene is
15–35% and 5–10% of adults with acute myeloid leukemia (AML), respectively. In addition,
point mutations, deletions, and insertions have been found in the juxtamembrane domain and in
the other codons within the kinase domain, though these are less common. Several large-scale
studies in well-documented patients published to date have demonstrated that FLT3 mutations are
strongly associated with a poor prognosis and a high leukemia cell count in patients with AML,
suggesting that FLT3 mutations are involved in disease progression. Because the detection of
FLT3 mutations is fast, easy, and inexpensive, mutation analysis should be performed as a routine
test. This chapter describes methods for detecting ITD and D835 mutations in the FLT3 gene.
Key Words: FLT3; internal tandem duplication; point mutation; deletion mutation; tyrosine
kinase; leukemia; molecular target.
1. Introduction
FLT3, a member of the receptor tyrosine kinase class III family, is preferentially
expressed on the surface of a high proportion of acute myeloid leukemia
(AML) and B-lineage acute lymphoblastic leukemia (ALL) cells as well as
hematopoietic stem cells (1–3). An interaction of FLT3 and its ligand has been
shown to play an important role in the survival, proliferation, and differentiation
of not only normal hematopoietic cells but also leukemia cells. Mutations
of the FLT3 gene were first reported as an internal tandem duplication (ITD) of
the juxtamembrane domain-coding sequence, and subsequently as a missense
mutation of D835 within the activation loop (4,5). In addition, point mutations,
deletions, and insertions have been found in the juxtamembrane domain and in
the other codons of the kinase domain, although these are less common (5–9)
(see Note 1). The prevalence of ITD and D835 mutations is 15–35% and 5–
10% of adults with AML, respectively. Thus, FLT3 mutation is currently the
From: Methods in Molecular Medicine, Vol. 125: Myeloid Leukemia: Methods and Protocols
Edited by: H. Iland, M. Hertzberg, and P. Marlton © Humana Press Inc., Totowa, NJ
189