Next generation sequencing (NGS) performed on peripheral blood‐derived CD34+ cells 5 years prior to T2‐ALL development revealed only the missense TET2P1962T mutation at a frequency of 1%, which increases to more than 40% in fully transformed leukaemic T2‐ALL and AML‐M0 clones. This evidence concerns the gene CD34 and acute lymphoblastic leukemia.