Genetic characterization of TET1, TET2, and TET3 alterations in myeloid malignancies

Abstract

Disease alleles that activate signal transduction are common in myeloid malignancies; however, there are additional unidentified mutations that contribute to myeloid transformation. Based on the recent identification of TET2 mutations, we evaluated the mutational status of TET1, TET2, and TET3 in myeloproliferative neoplasms (MPNs), chronic myelomonocytic leukemia (CMML), and acute myeloid leukemia (AML). Sequencing of TET2 in 408 paired tumor/normal samples distinguished between 68 somatic mutations and 6 novel single nucleotide polymorphisms and identified TET2 mutations in MPN (27 of 354, 7.6%), CMML (29 of 69, 42%), AML (11 of 91, 12%), and M7 AML (1 of 28, 3.6%) samples. We did not identify somatic TET1 or TET3 mutations or TET2 promoter hypermethylation in MPNs. TET2 mutations did not cluster in genetically defined MPN, CMML, or AML subsets but were associated with decreased overall survival in AML (P = .029). These data indicate that TET2 mutations are observed in different myeloid malignancies and may be important in AML prognosis.

Figure 1

Exons of TET2 with locations of mutations and effect of mutations on overall survival in AML. Locations of mutations in MPN (A), CMML (B), and AML/acute megakaryoblastic leukemia samples (C) as well Kaplan-Meier estimates of overall survival in AML (D) are shown. Shaded regions represent non–protein-coding exons and introns are not shown. Exons are drawn to relative scale. Missense mutations (down arrowheads), nonsense mutations (up arrowheads), and frameshifts (diamonds) are shown at their approximate location along the exon. Mutations occurring within the same patient sample are represented in the same color. Mutations that were homozygous are highlighted in yellow.