34 of the reported candidate driver mutations were previously reported (COSMIC 72) among which 29 in hematopoietic malignancies (COSMIC v72) including 26 in known T-ALL driver genes such as FBXW7, JAK1, JAK3, PHF6, KDM6A and NOTCH1. These variations were mostly clonal (mean variant allele frequency-VAF = 0.48, standard deviation-SD = 0.10), confirming their presence in the majority of tumor cells at diagnosis and their initiating role in T-ALL (Supplementary Figure S3 and Supplemental Information). Here, JAK3 is linked to acute lymphoblastic leukemia.