Mutations within CD34⁺ cells in lymphoma and AML. (A) CD34⁺ cells from a patient with B-cell lymphoma and AML carried 0, 1, or 2 mutations in TET2. (B) CD34⁺ cells from a patient with T-cell lymphoma that harbored biallelic TET2 mutations carried only 1 mutation in TET2 and either 3 or 4 additional mutations that were identified in the lymphoma.