Rothenberg-Thurley and coworkers have characterized paired pre-treatment and remission samples from 126 AML patients for mutations in all major leukemia-associated genes: at remission, 40% of patients retained ≥1 mutation, with a VAF (variant allele frequency) of ≥2%, with mutation persistence most frequent in DNMT3A, SRSF2, TET2 and ASXL1, associated with older age and with an inferior overall survival [21]. The gene discussed is TET2; the disease is acute myeloid leukemia.